LETTERS

to a
YOUNG SCIENTIST
Edward O. Wilson
Dedication
To the memory of my mentors,
Ralph L. Chermock and William L. Brown
CONTENTS
Cover
Title Page
Dedication
PROLOGUE
You Made the Right Choice
I THE PATH TO FOLLOW
1. First Passion, Then Training
2. Mathematics
3. The Path to Follow
II THE CREATIVE PROCESS
4. What Is Science?
5. The Creative Process
6. What It Takes
7. Most Likely to Succeed
8. I Never Changed
9. Archetypes of the Scientific Mind
10. Scientists as Explorers of the Universe
III. A LIFE IN SCIENCE
11. A Mentor and the Start of a Career
12. The Grails of Field Biology
13. A Celebration of Audacity
14. Know Your Subject, Thoroughly
IV. THEORY AND THE BIG PICTURE
15. Science as Universal Knowledge
16. Searching for New Worlds on Earth
17. The Making of Theories
18. Biological Theory on a Grand Scale
19. Theory in the Real World
V. TRUTH AND ETHICS
20. The Scientific Ethic
ACKNOWLEDGMENTS
PHOTOGRAPH CREDITS
About the Author
Copyright
Also by Edward O. Wilson
The foraminiferan Orbulina universa, a single-celled oceanic organism. Modified from photograph by Howard J. Spero, University of
California, Davis.
Prologue
YOU MADE THE RIGHT CHOICE
DEAR FRIEND,
From half a century of teaching students and young professionals in science, I feel privileged and
fortunate to have counseled many hundreds of talented and ambitious young people. As a result, I have
gleaned a deep knowledge, indeed a philosophy, of what you need to know to succeed in science. I
hope you will benefit from the thoughts and stories I will offer you in the letters to follow.
First and foremost, I urge you to stay on the path youve chosen, and to travel on it as far as you
can. The world needs youbadly. Humanity is now fully in the technoscientific age, and there is no
turning back. Although its rate of increase varies among its many disciplines, scientific knowledge
doubles every fifteen to twenty years. And so it has been since the 1600s, achieving a prodigious
magnitude today. And like all unfettered exponential growth given enough time, it seems decade by
decade to be ascending almost vertically. High technology runs at comparable pace alongside it.
Science and technology, bound in tight symbiotic alliance, pervade every dimension of our lives.
They hide no long-lasting secrets. They are open to everyone, everywhere. The Internet and all the
other accouterments of digital technology have rendered communication global and instant. Soon all
published knowledge in both science and the humanities will be available with a few keystrokes.
In case this assessment seems a bit feverish (although I suspect it is not, really), Ill provide an
example of a quantum leap in which I was fortunate to play a role. It occurred in taxonomy, the
classification of organisms, until recently a notoriously old-fashioned and sluggish discipline. Back in
1735, Carl Linnaeus, a Swedish naturalist who ranked with Isaac Newton as the best-known scientist
of the eighteenth century, launched one of the most audacious research projects of all time. He
proposed to discover and classify every kind of plant and animal on Earth. In 1759, to streamline the
process, he began to give each species a double Latinized name, such as Canis familiaris for the
domestic dog and Acer rubrum for the American red maple.
Linnaeus had no idea, not even to the power of 10 (that is, whether 10,000, or 100,000, or
1,000,000), of the magnitude of his self-assigned task. He guessed that plant species, his specialty,
would turn out to number around 10,000. The richness of the tropical regions were unknown to him.
The number of known and classified plant species today is 310,000 and is expected to reach 350,000.
When animals and fungi are added, the total number of species currently known is in excess of 1.9
millionand is expected to eventually reach 10 million or more. Of bacteria, the dark matter of
living diversity, only about 10,000 kinds are currently known (in 2013), but the number is
accelerating and is likely to add millions of species to the global roster. So, just as in Linnaeuss time
250 years ago, most of life on Earth remains unknown.
The still-deep pit of ignorance about biodiversity is a problem not just for specialists but for
everyone. How are we all going to manage the planet and keep it sustainable if we know so little
about it?
Until recently, the solution seemed out of reach. Hardworking scientists have been able to add only
about eighteen thousand new species each year. If this rate were to continue, it would take two
centuries or longer to account for all of Earths biodiversity, a period nearly as long as that from the
Linnaean initiative to the present time. What is the reason for this bottleneck? Until recently the
problem was one of technology, and it appeared insoluble. For historical reasons, the great bulk of
reference specimens and printed literature about them was confined to a relatively small number of
museums, located in a few cities in Western Europe and North America. To conduct basic research
on taxonomy, it was often necessary to visit these distant places. The only alternative was to arrange
to have the specimens and literature mailed, always a time-consuming and risky operation.
By the turn of the twenty-first century, biologists were looking for a technology that could somehow
solve the problem. In 2003 I suggested what in retrospect seems the obvious solution: the creation of
the online Encyclopedia of Life, which would include digitized, high-resolution photographs of
reference specimens, with all information on each species, updated continuously. It was to be an open
source, with new entries screened by curators expert in each group of species, such as centipedes,
bark beetles, and conifers. The project was funded by 2005, and with the parallel Census of Marine
Life, it has accelerated taxonomy, as well as those branches of biology dependent on accurate
classification. At the time I write, over half the known species on Earth have been incorporated. The
knowledge is available to anyone, anytime, anywhere, for free, at a keystroke (EOL.com).
So swift do advances like this in biodiversity studies occur, so startling the twists and turns in
every discipline, the future of the technoscientific revolution cannot be assayed for any branch of
science even just a decade ahead. Of course, there will come a time when the exponential growth in
discovery and cumulative knowledge must peak and level off. But that wont matter to you. The
revolution will continue for at least most of the twenty-first century, during which it will render the
human condition radically different from what it is today. Traditional disciplines of research will
metamorphose, by todays standards, into barely recognizable forms. In the process they will spin off
new fields of researchscience-based technology, technology-based science, and industry based on
technology and science. Eventually all of science will coalesce into a continuum of description and
explanation through which any educated person can travel by guidelines of principles and laws.
The introduction to science and scientific careers that I will give you in this series of letters is not
traditional in form or tone. I mean it to be as personal as possible, using my experiences in research
and teaching to provide a realistic image of the challenges and rewards you can expect as you pass
through a life in science.
I
THE PATH
to
FOLLOW
Merit badge symbol for Zoology in 1940. Boy Scout Handbook, Boy Scouts of America, fourth edition (1940).
One
FIRST PASSION, THEN TRAINING
I BELIEVE IT WILL HELP for me to start with this letter by telling you who I really am. This requires
your going back with me to the summer of 1943, in the midst of the Second World War. I had just
turned fourteen, and my hometown, the little city of Mobile, Alabama, had been largely taken over by
the buildup of a wartime shipbuilding industry and military air base. Although I rode my bicycle
around the streets of Mobile a couple of times as a potential emergency messenger, I remained
oblivious to the great events occurring in the city and world. Instead, I spent a lot of my spare time
not required to be at schoolearning merit badges in my quest to reach the Eagle rank in the Boy
Scouts of America. Mostly, however, I explored nearby swamps and forests, collecting ants and
butterflies. At home I attended to my menagerie of snakes and black widow spiders.
Global war meant that very few young men were available to serve as counselors at nearby Boy
Scout Camp Pushmataha. The recruiters, having heard of my extracurricular activities, had asked me,
I assume in desperation, to serve as the nature counselor. I was, of course, delighted with the prospect
of a free summer camp experience doing approximately what I most wanted to do anyway. But I
arrived at Pushmataha woefully underaged and underprepared in much of anything but ants and
butterflies. I was nervous. Would the other scouts, some older than I, laugh at what I had to offer?
Then I had an inspiration: snakes. Most people are simultaneously frightened, riveted, and
instinctively interested in snakes. Its in the genes. I didnt realize it at the time, but the south-central
Gulf coast is home to the largest variety of snakes in North America, upward of forty species. So
upon arrival I got some of the other campers to help me build some cages from wooden crates and
window screen. Then I directed all residents of the camp to join me in a summer-long hunt for snakes
whenever their regular schedules allowed.
Thereafter, on an average of several times a day, the cry rang out from somewhere in the woods:
Snake! Snake! All within hearing distance would rush to the spot, calling to others, while I, snake-
wrangler-in-chief, was fetched.
If nonvenomous, I would simply grab it. If venomous, I would first press it down just behind the
head with a stick, roll the stick forward until its head was immobile, then grasp it by the neck and lift
it up. Id then identify it for the gathering circle of scouts and deliver what little I knew about the
species (usually very little, but they knew less). Then we would walk to headquarters and deposit it
in a cage for a residence of a week or so. Id deliver short talks at our zoo, throw in something new I
learned about local insects and other animals. (I scored zero on plants.) The summer rolled by
pleasantly for me and my small army.
The only thing that could interrupt this happy career was, of course, a snake. I have since learned
that all snake specialists, scientists and amateurs alike, apparently get bitten at least once by a
venomous snake. I was not to be an exception. Halfway through the summer I was cleaning out a cage
that contained several pygmy rattlesnakes, a venomous but not deadly species. One coiled closer to
my hand than Id realized, suddenly uncoiled, and struck me on the left index finger. After first aid in
a doctors office near the camp, which was too late to do any good, I was sent home to rest my
swollen left hand and arm. Upon returning to Pushmataha a week later, I was instructed by the adult
director of the camp, as I already had been by my parents, that I was to catch no more venomous
snakes.
At the end of the season, as we all prepared to leave, the director held a popularity poll. The
campers, most of whom were assistant snake hunters, placed me second, just behind the chief
counselor. I had found my lifes work. Although the goal was not yet clearly defined then in my
adolescent mind, I was going to be a scientistand a professor.
Through high school I paid very little attention to my classes. Thanks to the relatively relaxed
school systems of south Alabama in wartime, with overworked and distracted teachers, I got away
with it. One memorable day at Mobiles Murphy High School, I captured with a sweep of my hand
and killed twenty houseflies, then lined them up on my desk for the next hours class to find. The
following day the teacher, a young lady with considerable aplomb, congratulated me but kept a closer
eye on me thereafter. That is all I remember, I am embarrassed to say, about my first year in high
school.
I arrived at the University of Alabama shortly after my seventeenth birthday, the first member of my
family on either side to attend college. I had by this time shifted from snakes and flies to ants. Now
determined to be an entomologist and work in the outdoors as much as possible, I kept up enough
effort to make As. I found that not very difficult (it is, Im told, very different today), but soaked up
all the elementary and intermediate chemistry and biology available.
Harvard University was similarly tolerant when I arrived as a Ph.D. student in 1951. I was
considered a prodigy in field biology and entomology, and was allowed to make up the many gaps in
general biology left from my happy days in Alabama. The momentum I built up in my southern
childhood and at Harvard carried through to an appointment at Harvard as assistant professor. There
followed more than six decades of fruitful work at this great university.
Ive told you my Pushmataha-to-Harvard story not to recommend my kind of eccentricity (although
in the right circumstances it could be of advantage); and I disavow my casual approach to early
formal education. I grew up in a different age. You, in contrast, are well into a different era, where
opportunity is broader but more demanding.
My confessional instead is intended to illustrate an important principle Ive seen unfold in the
careers of many successful scientists. It is quite simple: put passion ahead of training. Feel out in any
way you can what you most want to do in science, or technology, or some other science-related
profession. Obey that passion as long as it lasts. Feed it with the knowledge the mind needs to grow.
Sample other subjects, acquire a general education in science, and be smart enough to switch to a
greater love if one appears. But dont just drift through courses in science hoping that love will come
to you. Maybe it will, but dont take the chance. As in other big choices in your life, there is too much
at stake. Decision and hard work based on enduring passion will never fail you.
Reconstructed path of the Trojan asteroid 2010 TK
7
, during 165 years, seen from outside Earths orbit. Modified from drawing.
Paul Wiegert, University of Western Ontario.
Two
MATHEMATICS
LET ME MOVE ON quickly, and before everything else remaining, to a subject that is both a vital asset
for and a potential barrier to your career: mathematics, the great bugbear for many would-be
scientists. I mention this not to nag but to encourage and help. I mean in this letter to put you at ease. If
youre already well preparedlet us say youve picked up calculus and analytic geometryif you
like to solve puzzles, and if you think logarithms are a neat way to express variables across orders of
magnitude, then good for you; your capability is a comfort to me. I wont worry so much about you, at
least not right away. But keep in mind that a strong mathematical background does notI repeat, does
notguarantee success in science. I will return to this caveat later, so please stay focused. Actually, I
have a lot more to say to math lovers in particular.
If, on the other hand, you are a bit short in mathematical training, even very short, relax. You are far
from alone in the community of scientists, and here is a professional secret to encourage you: many of
the most successful scientists in the world today are mathematically no more than semiliterate. A
metaphor will clarify the paradox in this statement. Where elite mathematicians often serve as
architects of theory in the expanding realm of science, the remaining large majority of basic and
applied scientists map the terrain, scout the frontier, cut the pathways, and raise the first buildings
along the way. They define the problems that mathematicians, on occasion, may help solve. They think
primarily in images and facts, and only marginally in mathematics.
You may think me foolhardy, but its been my habit to brush aside the fear of mathematics when
talking to candidate scientists. During my decades of teaching biology at Harvard, I watched sadly as
bright undergraduates turned away from the possibility of a scientific career, or even from
nonrequired courses in the sciences, because they were afraid of failure in the math that might be
required. Why should I care? Because such math-phobes deprive science of an immeasurable amount
of sorely needed talent and deprive the many scientific disciplines of some of their most creative
young people. This is a hemorrhage of brainpower we need to stanch.
Now I will tell you how to ease your anxieties. Understand that mathematics is a language, ruled
like verbal languages by its own grammar and system of logic. Any person with average quantitative
intelligence who learns to read and write mathematics at an elementary level will have little difficulty
understanding math-speak.
Let me give you an example of the interplay of visual images and simple mathematical statements.
Ive chosen to reveal the undergirding of two relatively advanced disciplines in biology: population
genetics and population ecology.
Consider this interesting fact. You have (or had) 2 parents, 4 grandparents, 8 great-grandparents,
and 16 great-great-grandparents. In other words, since each person has to have two parents, the
number of your direct forebears doubles every generation. The mathematical summary is N = 2. The
parameter N is the number of a persons ancestors x generations back in time. How many of your
ancestors existed 10 generations ago? We dont have to write out each generation in turn. Instead you
can use N = 2 = 2, or, put the other way, 2 = N. So the answer is when x = 10 generations, you have N
= 1,024 ancestors. Now reverse the timeline to forward and ask how many descendants you can
expect to have 10 generations from now. The whole thing gets much more complicated in the case of
descendantswe dont really know how many children we will havebut to state the basic idea, it
is all right to specify, in a way mathematicians often do, that each couple will have two surviving
children and the length of the generations will be constant from one generation to the next. (Two
children on average is not far from the actual rate in the United States today, and is close to the
number 2.1, or 21 children for every 100 couples, needed to maintain a constant population size of
native-born.) Then in 10 generations you will have 1,024 descendants.
What are we to make of this? For one thing, it is a humbling picture of the origin and the fate of one
persons genes. The fact is that sexual reproduction chops apart the combinations that prescribe each
persons traits and recombines half of them with somebody elses genes to make the next generation.
Over a very few generations, each parents combination will be dissolved in the gene pool of the
population as a whole. Suppose you have a distinguished forebear who fought in the American
Revolution, during which another roughly 250 of your other direct ancestors lived, including possibly
a horse thief or two or three. (One of my 8 great-great-grandfathers, a confederate veteran of the Civil
War, was a notoriously tricky horse trader, if not quite a thief.)
Mathematicians like to take the measurement of exponential growth from just counting jumps from
one generation to the next, to the much more general state to fit a large population over a particular
moment in time (to the hour, minute, or shorter interval as they choose). This is done with calculus,
which expresses the growth of population in the form dN/dt = rN, which says in any very short
interval of time, dt, the population is growing a certain amount, dN, and the rate is the differential
dN/dt. In the case of exponential growth, N, the number of individuals in the population at the instant
is multiplied by r, a constant that depends on the nature of the population and the circumstances in
which it lives.
You can pick any N and r that interests you, and run with these two parameters for as long as you
choose. If the differential dN/dt is larger than zero and the population (say, of bacteria or mice or
humans) is allowed in theory to increase at the same rate indefinitely, in a surprising few years the
population would weigh more than Earth, than the solar system, and finally than the entire known
universe.
It is easy to produce fantastical results with mathematically correct theory. There are a lot of
models that fit reality and produce factual implications that can jolt us into a new way of thinking. A
famous one learned from exponential growth of the kind Ive just described is the following. Suppose
there is a pond, and a lily pad is put in the pond. This first pad doubles into two pads, each of which
also doubles. The pond will fill and no more pads can double at the end of thirty days. When is the
pond half full? On the twenty-ninth day. This elementary bit of mathematics, obvious upon
commonsense reflection, is one of many ways to emphasize the risks of excessive population growth.
For two centuries the global human population has been doubling every several generations. Most
demographers and economists agree that a global population of more than ten billion would make it
very difficult to sustain the planet. We recently shot past seven billion. When was the Earth half full?
Decades ago, say the experts. Humanity is racing toward the wall.
The longer you wait to become at least semiliterate in math, the harder the language of mathematics
will be to masteragain the same as in verbal languages. But it can be done, and at any age. I speak
as an authority on this subject, because I am an extreme case. Having spent my pre-college years in
relatively poor southern schools, I didnt take algebra until my freshman year at the University of
Alabama. My student days being at the end of the Depression, algebra just wasnt offered. I finally got
around to calculus as a thirty-two-year-old tenured professor at Harvard, where I sat uncomfortably
in classes with undergraduate students only a bit more than half my age. A couple of them were
students in a course on evolutionary biology I was teaching. I swallowed my pride and learned
calculus.
Admittedly, I was never more than a C student while catching up, but I was reassured somewhat by
the discovery that superior mathematical ability is similar to fluency in foreign languages. I might
have become fluent with more effort and sessions talking with the natives, but, being swept up with
field and laboratory research, I advanced only by a small amount.
A true gift in mathematics is probably hereditary in part. What this means is that variation within a
group in ability is due in some measurable degree to differences in genes among the group members
rather than entirely just to the environment in which they grew up. There is nothing that you and I can
do about hereditary differences, but it is possible to greatly reduce the part of the variation due to the
environment simply by raising our ability through education and practice. Mathematics is convenient
in that it can be achieved by self-instruction.
Having gone this far, I believe I should go on a bit further, and explain how fluency is achieved by
those who wish to attain it. Practice allows elementary operations (such as, If y = x + 2, then x = y -
2) to be effortlessly retrieved in memory, much like words and phrases (such as effortlessly
retrieved in memory). Then, in the way verbal phrases are almost unconsciously put together in
sentences and sentences are built into paragraphs, mathematical operations can be put together with
ease in ever more complex sequences and structures. There is, of course, much more to mathematical
reasoning. There are, for example, the positioning and proving of theorems, the exploration of series,
and the invention of new modes of geometry. But short of these adventures of advanced pure
mathematics, the language of mathematicians can be learned well enough to understand the majority of
mathematical statements made in scientific publications.
Exceptional mathematical fluency is required in only a few disciplines. Particle physics,
astrophysics, and information theory come to mind. Far more important throughout the rest of science
and its applications, however, is the ability to form concepts, during which the researcher conjures
images and processes in visual images by intuition. Its something everyone already does to some
degree.
In your imagination, be the great eighteenth century physicist Isaac Newton. Think of an object
falling through space. (In the legend, he was attracted to an apple falling from the tree to the ground.)
Make it from high up, like a package dropped from an airplane. The object accelerates to about 120
miles an hour, then holds that velocity until it hits the ground. How can you account for this
acceleration up to but not beyond terminal velocity? By Newtons laws of motion, plus the existence
of air pressure, the kind used to propel a sailboat.
Stay as Newton a moment longer. Notice as he did how light passing through curved glass
sometimes comes out as a rainbow of colors, always ranging from red to yellow to green to blue to
violet. Newton thought that white light is just a mix of the colored lights. He proved it by passing the
same array of colors back through a prism, turning the mix back into white light. Scientists were later
to understand, from other experiments and mathematics, that the colors are radiations differing in
wavelength. The longest we are able to see creates the sensation of red, and the shortest the sensation
of blue.
You likely knew all that already. Whether you did or not, lets go on to Darwin. As a young man in
the 1830s, he made a five-year voyage on a British government vessel, the HMS Beagle, around the
coast of South America. He took that long period to explore and think broadly and deeply about the
natural world. He found, for example, a lot of fossils, some of extinct large animals similar to modern
species like horses, tigers, and rhinocerosesyet different in many important ways than these modern
equivalents. Were they just victims of the biblical flood that Noah failed to save? But that couldnt
be, Darwin must have realized; Noah saved all the kinds of animals. The South American species
were obviously not among them.
As the young naturalist went from one part of the continent to another, he noticed something else:
some kinds of living birds and other animals found in one locality were replaced by closely similar
yet distinctly different kinds in another. What, he must have thought, is going on here? Today we know
it was evolution, but that answer was not open to the young man. Anything that so openly contradicted
holy scripture was considered heresy back home in England, and Darwin had trained for the ministry
at the University of Cambridge.
When he finally accepted evolution, during the voyage back home, he soon began puzzling over the
cause of evolution. Was it divine guidance? Not likely. The inheritance of changes caused directly by
the environment, as suggested earlier by the French zoologist Jean-Baptiste Lamarck? Others had
already rejected that theory. How about progressive change built into the heredity of organisms that
unfolds from one generation to the next? That was hard to imagine, and in any case Darwin was soon
figuring out another process, natural selection, in which varieties within a speciesvarieties that
survive longer, reproduce more, or bothreplace other, less successful varieties in the same species.
The idea and its supporting logic came in pieces to Darwin while walking around his rural home,
riding in a carriage, or, in one important case, sitting in his garden staring at an anthill. Darwin
admitted later that if he couldnt explain how sterile ant workers passed on their worker anatomy and
behavior to later generations of sterile ant workers, he might have to abandon his theory of evolution.
He conceived the following solution: the worker traits are passed on through the mother queen;
workers have the same heredity as the queen, but are reared in a different, stultifying environment.
One day, during this lucubration, when a housemaid saw him staring at an anthill in the garden, she
made reference to a famous prolific novelist living nearby when she said (it is reported), What a
pity Mr. Darwin doesnt have a way to pass his time, like Mr. Thackeray.
Everyone sometimes daydreams like a scientist at one level or another. Ramped up and
disciplined, fantasies are the fountainhead of all creative thinking. Newton dreamed, Darwin
dreamed, you dream. The images evoked are at first vague. They may shift in form and fade in and
out. They grow a bit firmer when sketched as diagrams on pads of paper, and they take on life as real
examples are sought and found.
Pioneers in science only rarely make discoveries by extracting ideas from pure mathematics. Most
of the stereotypical photographs of scientists studying rows of equations written on blackboards are
instructors explaining discoveries already made. Real progress comes in the field writing notes, at the
office amid a litter of doodled paper, in the corridor struggling to explain something to a friend, at
lunchtime, eating alone, or in a garden while walking. To have a eureka moment requires hard work.
And focus. A distinguished researcher once commented to me that a real scientist is someone who can
think about a subject while talking to his or her spouse about something else.
Ideas in science emerge most readily when some part of the world is studied for its own sake. They
follow from thorough, well-organized knowledge of all that is known or can be imagined of real
entities and processes within that fragment of existence. When something new is encountered, the
follow-up steps will usually require the use of mathematical and statistical methods in order to move
its analysis forward. If that step proves technically too difficult for the person who made the
discovery, a mathematician or statistician can be added as a collaborator. As a researcher who has
coauthored many papers with mathematicians and statisticians, I offer the following principle with
confidence. Lets call it Principle Number One:
It is far easier for scientists to acquire needed collaboration from mathematicians and
statisticians than it is for mathematicians and statisticians to find scientists able to make use of
their equations.
For example, when I sat down in the late 1970s with the mathematical theorist George Oster to
work out the principles of caste and division of labor in the social insects, I supplied the details of
what had been discovered in nature and in the laboratory. Oster then drew methods from his diverse
toolkit to create theorems and hypotheses concerning this real world laid before him. Without such
information Oster might have developed a general theory in abstract terms that covers all possible
permutations of castes and division of labor in the universe, but there would have been no way of
deducing which ones of these multitude options exist on Earth.
This imbalance in the role of observation and mathematics is especially the case in biology, where
factors in a real-life phenomenon are often either misunderstood or never noticed in the first place.
The annals of theoretical biology are clogged with mathematical models that either can be safely
ignored or, that when tested, fail. Possibly no more than 10 percent have any lasting value. Only those
linked solidly to knowledge of real living systems have much chance of being used.
If your level of mathematical competence is low, plan on raising it, but meanwhile know that you
can do outstanding work with what you have. Such is markedly true in fields built largely upon the
amassing of data, including, for example, taxonomy, ecology, biogeography, geology, and
archaeology. At the same time, think twice about specializing in fields that require a close alternation
of experiment and quantitative analysis. These include the greater part of physics and chemistry, as
well as a few specialties within molecular biology. Learn the basics of improving your mathematical
literacy as you go along, but if you remain weak in mathematics, seek happiness elsewhere among the
vast array of scientific specialties. Conversely, if tinkering and mathematical analysis give you joy,
but not the amassing of data for their own sake, stay away from taxonomy and the other more
descriptive disciplines just listed.
Newton, for example, invented calculus in order to give substance to his imagination. Darwin by
his own admission had little or no mathematical ability, but was able with masses of information he
had accumulated to conceive a process to which mathematics was later applied. An important step for
you to take is to find a subject congenial to your level of mathematical competence that also interests
you deeply, and focus on it. In so doing, keep in mind Principle Number Two:
For every scientist, whether researcher, technologist, or teacher, of whatever competence in
mathematics, there exists a discipline in science for which that level of mathematical
competence is enough to achieve excellence.
A relativistic jet formed as gas and stars fall into a black hole; artists conception. Modified from painting by Dana Berry of the Space
Telescope Science Institute (STScI). http://hubblesite.org/newscenter/archive/releases/1990/29/image/a/warn/.
Three
THE PATH TO FOLLOW
THE PURPOSE OF THIS LETTER is to help orient you among your colleagues.
When I was a sixteen-year-old senior in high school, I decided the time had come to choose a
group of animals on which to specialize when I entered college the coming fall. I thought about spear-
winged flies of the taxonomic family Dolichopodidae, whose tiny bodies sparkle like animated
gemstones in the sun. But I couldnt get the right equipment or literature to study them. So I turned to
ants. By sheer luck, it was the right choice.
Arriving at the University of Alabama at Tuscaloosa, with my well-prepared and identified
beginners collection of ants, I reported to the biology faculty to begin my freshman year of research.
Perhaps charmed by my navet, or perhaps recognizing an embryonic academic when they saw one,
or both, I was welcomed by the faculty and given a stage microscope and personal laboratory space.
This support, on top of my earlier success as nature counselor at Camp Pushmataha, buoyed my
confidence that I had the right subject and the right university.
My good fortune came from an entirely different source, however. It was choosing ants in the first
place. These little six-legged warriors are the most abundant of all insects. As such, they play major
roles in land environments around the world. Of equal importance for science, ants, along with
termites and honeybees, have the most advanced social systems of all animals. Yet, surprisingly, at
the time I entered college only about a dozen scientists around the world were engaged full-time in
the study of ants. I had struck gold before the rush began. Almost every research project I began
thereafter, no matter how unsophisticated (and all were unsophisticated), yielded discoveries
publishable in scientific journals.
What does my story mean to you? A great deal. I believe that other experienced scientists would
agree with me that when you are selecting a domain of knowledge in which to conduct original
research, it is wise to look for one that is sparsely inhabited. Judge opportunity by how few there are
of other students and researchers in one field versus another. This is not to deny the essential
requirement of broad training, or the value of apprenticing yourself to researchers and programs of
high quality. Or that it also helps to make a lot of friends and colleagues of your age in science for
mutual support.
Nonetheless, through it all, I advise you to look for a chance to break away, to find a subject you
can make your own. That is where the quickest advances are likely to occur, as measured by
discoveries per investigator per year. Therein you have the best chance to become a leader and, as
time passes, to gain growing freedom to set your own course.
If a subject is already receiving a great deal of attention, if it has a glamorous aura, if its
practitioners are prizewinners who receive large grants, stay away from that subject. Listen to the
news coming from the current hubbub, learn how and why the subject became prominent, but in
making your own long-term plans be aware it is already crowded with talented people. You would be
a newcomer, a private amid bemedaled first sergeants and generals. Take a subject instead that
interests you and looks promising, and where established experts are not yet conspicuously competing
with one another, where few if any prizes and academy memberships have been given, and where the
annals of research are not yet layered with superfluous data and mathematical models. You may feel
lonely and insecure in your first endeavors, but, all other things being equal, your best chance to make
your mark and to experience the thrill of discovery will be there.
You may have heard the military rule for the summoning of troops to a battlefield: March to the
sound of the guns. In science the opposite is the one for you, as expressed in Principle Number
Three:
March away from the sound of the guns. Observe the fray from a distance, and while you are at
it, consider making your own fray.
Once you have settled upon a subject you can love, your potential to succeed will be greatly
enhanced if you study it enough to become a world-class expert. This goal is not as difficult as it may
seem, even for a graduate student. It is not overly ambitious. There are thousands of subjects in
science, sprinkled through physics and chemistry, biology and the social sciences, where it is
possible in a short time to attain the status of an authority. If the subject is still thinly populated, you
can with diligence and hard work even become the world authority at a young age. Society needs this
level of expertise, and it rewards the kind of people willing to acquire it.
The already existing information, and what you yourself will discover, may at first be skimpy and
difficult to connect to other bodies of knowledge. If this proves to be the case, thats very good. Why
should the path to a scientific frontier usually be hard rather than easy? The answer is stated as
Principle Number Four:
In the search for scientific discoveries, every problem is an opportunity. The more difficult the
problem, the greater the likely importance of its solution.
The truth of this guidebook dictum can be most clearly seen in extreme cases. The sequencing of the
human genome, the search for life on Mars, and the finding of the Higgs boson were each of profound
importance for medicine, biology, and physics, respectively. Each required the work of thousands,
and cost billions. Each was worth all the trouble and expense. But on a far smaller scale, in fields
and subjects less advanced, a small squad of researchers, even a single individual, can with effort
devise an important experiment at relatively low cost.
This brings me to the ways in which scientific problems are found and discoveries made.
Scientists, mathematicians among them, follow one of two pathways. First, early in the research a
problem is identified, and then a solution is sought. The problem may be relatively small (for
example, what is the average life span of a Nile crocodile?) or large (what is the role of dark matter
in the universe?). As an answer emerges, other phenomena are typically discovered, and other
questions raised. The second strategy is to study a subject broadly, while searching for any
previously unknown or even unimagined phenomena. The two strategies of original scientific
research are stated as Principle Number Five:
For every problem in a given discipline of science, there exists a species or other entity or
phenomenon ideal for its solution. (Example: a kind of mollusk, the sea hare Aplysia, proved
ideal for exploring the cellular base of memory.)
Conversely, for every species or other entity or phenomenon, there exist important problems
for the solution of which it is ideally suited. (Example: bats were logical for the discovery of
sonar.)
Obviously, both strategies can be followed, together or in sequence, but by and large scientists
who use the first strategy are instinctive problem solvers. They are prone by taste and talent to select
a particular kind of organism, or chemical compound, or elementary particle, or physical process, to
answer questions about its properties and roles in nature. Such is the predominant research activity in
the physical sciences and molecular biology.
The following example is a fictitious scenario of the first strategy, but, I promise you, is close to
true dramas that occur in laboratories:
Think of a small group of white-coated men and women in a laboratoryearly one afternoon,
let us saywatching the readout on a digital monitor. That morning, before setting up the
experiment, they were in a nearby conference room, conferring, occasionally taking turns at
the blackboard to make an argument. With coffee break, lunch, a few jokes, they decide to try
this or that. If the data in the readout are as expected, that will be very interesting, a real
lead. It would be what were looking for, the team leader says. And it is! The object of the
search is the role of a new hormone in the mammalian body. First, though, the team leader
says, Lets break out some champagne. Tonight, well all have dinner at a decent restaurant
and start talking about what comes next.
In biology, the first, problem-oriented strategy (for every problem, an ideal organism) has resulted
in a heavy emphasis on several dozen model species. When in your studies you take up the
molecular basis of heredity you will learn a great deal that came from a bacterium living in the human
gut, E. coli (condensed from its full scientific name, Escherichia coli). For the organization of cells
in the nervous system, there is inspiration from the roundworm C. elegans (Caenorhabditis elegans).
And for genetics and embryonic development, you will become familiar with fruitflies of the iconic
genus Drosophila. This is, of course, as it should be. Better to know one thing in depth rather than a
dozen things at their surface only.
Still, keep in mind that during the next few decades there will be at most only a few hundred model
species, out of close to two million other species known to science by scarcely more than a brief
diagnosis and a Latinized name. Although the latter multitude tend to possess most of the same basic
processes discovered in the model species, they further display among them an immense array of
idiosyncratic traits in anatomy, physiology, and behavior. Think, in one sweep of your mind, first of a
smallpox virus, then of all you know about it. Then the same for an amoeba, and then on to a maple
tree, blue whale, monarch butterfly, tiger shark, and human being. The point is that each such species
is a world unto itself, with a unique biology and place in an ecosystem, and, not least, an evolutionary
history thousands to millions of years old.
When a biologist studies a group of species, ranging anywhere from, say, elephants with three
living species to ants with fourteen thousand species, he or she typically aims to learn everything
possible over a wide range of biological phenomena. Most researchers working this way, following
the second strategy of research, are properly called scientific naturalists. They love the organisms
they study for their own sake. They enjoy studying creatures in the field, under natural conditions.
They will tell you, correctly, that there is infinite detail and beauty even in those that people at first
find least attractiveslime molds, for example, dung beetles, cobweb spiders, and pit vipers. Their
joy is in finding something new, the more surprising the better. They are the ecologists, taxonomists,
and biogeographers. Here is a scenario of a kind I have personally experienced many times:
Think of two biologists hunting in a rain forest, packing heavy collecting equipment, with an
online field guide waiting back at camp and DNA analysis at the home laboratory. Good
God, what is that? one says, pointing to a small, strangely shaped, brilliantly colored
animal plastered onto the underside of a palm leaf. I think its a hylid frog, his companion
replies. No, no, wait, Ive never seen anything like it. Its got to be something new. What the
hell is it? Listen, get close, and be careful, dont lose it. There, got it. Were not going to
preserve it yet. You never know, it might be an endangered species. Lets take it back alive to
camp and see what we can find on the Encyclopedia of Life website. Theres that guy at
Cornell, he knows all the amphibians like this one pretty well, I think. We might check in with
him. First, though, we ought to look around for more specimens, get all the information we
can. The pair arrive back at camp and start pulling up information. What they find is
astonishing. The frog appears to be a new genus, unrelated to any other previously known.
Scarcely believing, the pair go online to spread news of the discovery to other specialists
around the world.
The potential paths you can follow with a scientific career are vast in number. Your choice may
take you into one of the scenarios Ive described, or not. The subject for you, as in any true love, is
one in which you are interested and that stirs passion and promises pleasure from a lifetime of
devotion.
II
THE
CREATIVE
PROCESS
Charles Darwin at 31 years of age. Modified from painting by George Richmond.
Four
WHAT IS SCIENCE?
WHAT IS THIS grand enterprise called science that has lit up heaven and earth and empowered
humanity? It is organized, testable knowledge of the real world, of everything around us as well as
ourselves, as opposed to the endlessly varied beliefs people hold from myth and superstition. It is the
combination of physical and mental operations that have become increasingly the habit of educated
peoples, a culture of illuminations dedicated to the most effective way ever conceived of acquiring
factual knowledge.
You will have heard the words fact, hypothesis, and theory used constantly in the conduct of
scientific research. When separated from experience and spoken of as abstract ideas they are easily
misunderstood and misapplied. Only in case histories of research, by others and soon by you, will
their full meaning become clear.
Ill give you an example of my own to show you what I mean. I started with a simple observation:
ants remove their dead from the nests. Those of some species just dump the corpses at random
outside, while those of other species place them on piles of refuse that might be called cemeteries.
The problem I saw in this behavior was simple but interesting: How does an ant know when another
ant is dead? It was obvious to me that the recognition was not by sight. Ants recognize a corpse even
in the complete darkness of the underground nest chambers. Furthermore, when the body is fresh and
in a lighted area, and even when it is lying on its back with its legs in the air, others ignore it. Only
after a day or two of decomposition does a body become a corpse to another ant. I guessed (made a
hypothesis) that the undertaker ants were using the odor of decomposition to recognize death. I further
thought it likely (second hypothesis) that their response was triggered by only a few of the substances
exuded from the body of the corpse. The inspiration for the second hypothesis was an established
principle of evolution: animals with small brains, which are the vast majority of animals on Earth,
tend to use the simplest set of available cues to guide them through life. A dead body offers dozens or
hundreds of chemical cues from which to choose. Human beings can sort out these components. But
ants, with brains one-millionth the size of our own, cannot.
So if the hypotheses are true, which of these substances might trigger the undertaker responseall
of them, a few of them, or none? From chemical suppliers I obtained pure synthetic samples of
various decomposition substances, including skatole, the essence of feces; trimethylamine, the
dominant odor of rotting fish; and various fatty acids and their esters of a kind found in dead insects.
For a while my laboratory smelled like a combination of charnel house and sewer. I put minute
amounts on dummy ant corpses made of paper and inserted them into ant colonies. After a lot of
smelly trial and error I found that oleic acid and one of its oleates trigger the response. The other
substances were either ignored or caused alarm.
To repeat the experiment another way (and admittedly for my and others amusement), I dabbed
tiny amounts of oleic acid on the bodies of living worker ants. Would they become the living dead?
Sure enough, they did become zombies, at least broadly defined. They were picked up by nestmates,
their legs kicking, carried to the cemetery, and dumped. After they had cleaned themselves awhile,
they were permitted to rejoin the colony.
I then came up with another idea: insects of all kinds that scavenge for a living, such as blowflies
and scarab beetles, find their way to dead animals or dung by homing in on the scent. And they do so
by using a very small number of the decomposition chemicals present. A generalization of this kind,
widely applied, with at least a few facts here and there and some logical reasoning behind it, is a
theory. Many more experiments, applied to other species, would be required to turn it into what can
be confidently called a fact.
What, then, in broadest terms is the scientific method? The method starts with the discovery of a
phenomenon, such as a mysterious ant behavior, or a previously unknown class of organic
compounds, or a newly discovered genus of plants, or a mysterious water current in the oceans
abyss. The scientist asks: What is the full nature of this phenomenon? What are its causes, its origin,
its consequence? Each of these queries poses a problem within the ambit of science. How do
scientists proceed to find solutions? Always there are clues, and opinions are quickly formed from
them concerning the solutions. These opinions, or just logical guesses as they often are, are the
hypotheses. It is wise at the outset to figure out as many different solutions as seem possible, then test
the whole, either one at a time or in bunches, eliminating all but one. This is called the method of
multiple competing hypotheses. If something like this analysis is not followedand, frankly, it often
is notindividual scientists tend to fixate on one alternative or another, especially if they authored it.
After all, scientists are human.
Only rarely does an initial investigation result in a clear delineation of all possible competing
hypotheses. This is especially the case in biology, in which multiple factors are the rule. Some factors
remain undiscovered, and those that have been discovered commonly overlap and interact with one
another and with forces in the environment in ways difficult to detect and measure. The classic
example in medicine is cancer. The classic example in ecology is the stabilization of ecosystems.
So scientists shuffle along as best they can, intuiting, guessing, tinkering, gaining more information
along the way. They persist until solid explanations can be put together and a consensus emerges,
sometimes quickly but at other times only after a long period.
When a phenomenon displays invariable properties under clearly defined conditions, then and only
then can a scientific explanation be declared to be a scientific fact. The recognition that hydrogen is
one of the elements, incapable of being divided into other substances, is a fact. That an excess of
mercury in the diet causes one disease or another can, after enough clinical studies are conducted, be
declared a fact. It may be widely believed that mercury causes an entire class of similar maladies,
due to the one or two known chemical reactions in cells of the body. This idea may or may not be
confirmed by further studies on diseases believed affected in this manner by mercury. Meanwhile,
however, when research is still incomplete, the idea is a theory. If the theory is proved wrong, it was
not necessarily also altogether a bad theory. At least it will have stimulated new research, which
adds to knowledge. That is why many theories, even if they fail, are said to be heuristicthey are
good for the promotion of discovery. Incidentally, the source of the word eurekaI have found
it!descends from the legend of the Greek scientist Archimedes, who, while sitting in a public bath,
imagined how to measure the density of an object regardless of its shape. Put it in water, measure its
volume by the rise in the water level, and its weight by how fast it sinks in the water. The density is
the amount of weight divided by the amount of volume. Archimedes is said to have then left the bath,
running through the streets, hopefully in his robe, while shouting, Heurika! Specifically, hed found
how to determine whether a crown was pure gold. The pure substance has a higher density than gold
mixed with silver, the lesser of the two noble metals. But of far greater importance, Archimedes had
discovered how to measure the density of all solids regardless of their shape or composition.
Now consider a much grander example of the scientific method. It has been commonly said, all the
way back to the publication of Charles Darwins On the Origin of Species in 1859, that the evolution
of living forms is just a theory, not a fact. What could have been said already from evidence in
Darwins time, however, was that evolution is a fact, that it has occurred in at least some kinds of
organisms some of the time. Today the evidence for evolution has been so convincingly documented
in so many kinds of plants, fungi, animals, and microorganisms, and in such a great array of their
hereditary traits, coming from every discipline of biology, all interlocking in their explanations and
with no exception yet discovered, that evolution can be called confidently a fact. In Darwins time,
the idea that the human species descended from early primate ancestors was a hypothesis. With
massive fossil and genetic evidence behind it, that can now also be called a fact. What remains a
theory still is that evolution occurs universally by natural selection, the differential survival and
successful reproduction of some combinations of hereditary traits over others in breeding
populations. This proposition has been tested so many times and in so many ways, it also is now
close to deserved recognition as an established fact. Its implication has been and remains of
enormous importance throughout biology.
When a well-defined and precisely consistent process is observed, such as ions flowing in a
magnetic field, a body moving in airless space, and the volume of a gas changing with temperature,
the behavior can be precisely measured and mathematically defined as a law. Laws are more
confidently sought in physics and chemistry, where they can be most easily extended and deepened by
mathematical reasoning. Does biology also have laws?
I have been so bold in recent years as to suggest that, yes, biology is ruled by two laws. The first is
that all entities and processes of life are obedient to the laws of physics and chemistry. Although
biologists themselves seldom speak of the connection, at least in such a manner, those working at the
level of the molecule and the cell assume it to be true. No scientist of my acquaintance believes it
worthwhile to search for what used to be called the lan vital, a physical force or energy unique to
living organisms.
The second law of biology, more tentative than the first, is that all evolution, beyond minor random
perturbations due to high mutation rates and random fluctuations in the number of competing genes, is
due to natural selection.
A source of the ground strength of science are the connections made not only variously within
physics, chemistry, and biology, but also among these primary disciplines. A very large question
remains in science and philosophy. It is as follows: Can this consilienceconnections made between
widely separated bodies of knowledgebe extended to the social sciences and humanities, including
even the creative arts? I think it can, and further I believe that the attempt to make such linkages will
be a key part of intellectual life in the remainder of the twenty-first century.
Why do I and others think in this controversial manner? Because science is the wellspring of
modern civilization. It is not just another way of knowing, to be equated with religion or
transcendental meditation. It takes nothing away from the genius of the humanities, including the
creative arts. Instead it offers ways to add to their content. The scientific method has been
consistently better than religious beliefs in explaining the origin and meaning of humanity. The
creation stories of organized religions, like science, propose to explain the origin of the world, the
content of the celestial sphere, and even the nature of time and space. These mythic accounts, based
mostly on the dreams and epiphanies of ancient prophets, vary from one religions belief to another.
Colorful they are, and comforting to the minds of believers, but each contradicts all the others. And
when tested in the real world they have so far proved wrong, always wrong.
The failure of the creation stories is further evidence that the mysteries of the universe and the
human mind cannot be solved by unaided intuition. The scientific method alone has liberated humanity
from the narrow sensory world bequeathed it by our prehuman ancestors. Once upon a time humans
believed that light allowed them to see everything. Now we know that the visual spectrum, which
activates the visual cortex of the brain, is only a sliver of the electromagnetic spectrum, where the
frequencies range across many orders of magnitude, from those of extreme high-frequency gamma
rays at one end to those at the extreme low-frequency radiation at the other. The analysis of the
electromagnetic spectrum has led to an understanding of the true nature of light. Knowledge of its
totality has made possible countless advances in science and technology.
Once people thought that Earth was the center of the universe and lay flat and unmoving while the
sun rotated around it. Now we know that the sun is a star, one of two hundred million in the Milky
Way galaxy alone. Most hold planets in their gravitational thrall, and many of these almost certainly
resemble Earth. Do the Earthlike planets also harbor life? Probably, in my opinion, and, thanks to the
scientific method, furnished with improved optics and spectroscopic analyses, we will know in a
short time.
Once it was believed that the human race arose full-blown in its present form as a supernatural
event. Now we understand, in sharp contrast, that our species descended over six million years from
African apes that were also the ancestors of modern chimpanzees.
As Freud once remarked, Copernicus demonstrated that Earth is not at the center of the universe,
Darwin that we are not the center of life, and he, Freud, that we are not even in control of our own
minds. Of course, the great psychoanalyst must share credit with Darwin, among others, but the point
is correct that the conscious mind is only part of the thinking process.
Overall, through science we have begun to answer in a more consistent and convincing way two of
the great and simple questions of religion and philosophy: Where do we come from? and, What are
we? Of course, organized religion claims to have answered these questions long ago, using
supernatural creation stories. You might then well ask, can a religious believer who accepts one such
story still do good science? Of course he can. But he will be forced to split his worldview into two
domains, one secular and the other supernatural, and stay within the secular domain as he works. It
would not be difficult for him to find endeavors in scientific research that have no immediate relation
to theology. This suggestion is not meant to be cynical, nor does it imply a closing of the scientific
mind.
If proof were found of a supernatural entity or force that affects the real world, the claim all
organized religions make, it would change everything. Science is not inherently against such a
possibility. Researchers in fact have every reason to make such a discovery, if any such is feasible.
The scientist who achieved it would be hailed as the Newton, Darwin, and Einstein, all put together,
of a new era in history. In fact, countless reports have been made throughout the history of science that
claim evidence of the supernatural. All, however, have been based on attempts to prove a negative
proposition. It usually goes something like this: We havent been able to find an explanation for
such-and-such a phenomenon; therefore it must have been created by God. Present-day versions still
circulating include the argument that because science cannot yet provide a convincing account of the
origin of the universe and of the setting of the universal physical constants, there must be a divine
Creator. A second argument heard is that because some molecular structures and reactions in the cell
seem too complex (to the author of the argument, at least) to have been assembled by natural
selection, they must have been designed by a higher intelligence. And one more: because the human
mind, and especially free will as a key part of it, appear beyond the capability of the material cause
and effect, they must have been inserted by God.
The difficulty with reliance on negative hypotheses to support faith-based science is that if they are
wrong, they are also very vulnerable to decisive disproof. Just one testable proof of a real, physical
cause destroys the argument for a supernatural cause. And precisely this in fact has been a large part
of the history of science, as it has unfolded, phenomenon by phenomenon. The world rotates around
the sun, the sun is one star out of two hundred million or more in one galaxy out of hundreds of
billions of galaxies, humanity descended from African apes, genes change by random mutations, the
mind is a physical process in a physical organ. Yielding to naturalistic, real-world understanding, the
divine hand has withdrawn bit by bit from almost all of space and time. The remaining opportunities
to find evidence of the supernatural are closing fast.
As a scientist, keep your mind open to any possible phenomenon remaining in the great unknown.
But never forget that your profession is exploration of the real world, with no preconceptions or idols
of the mind accepted, and testable truth the only coin of the realm.
The potential community of contacts in contemporary human relationships (lines) is illustrated by political blogs (dots) in the 2004 U.S.
presidential election. The same applies to disciplines of science. Modified from The political blogosphere and the 2004 U.S. election:
divided they blog, by Lada A. Adamic and Natalie Glance, Proceedings of the 3rd International Workshop on Link Discovery
(Link KDD05) 1: 3643 (2005).
Five
THE CREATIVE PROCESS
TO KNOW HOW scientists engage in visual imagery is to understand how they think creatively.
Practicing it yourself while you receive your technical training will bring you close to the heart of the
scientific enterprise. When earlier I said you can surely succeed, I also assumed that you are able to
daydream. But be prepared mentally for some amount of chaos and failure. Waste and frustration
often attend the earliest stages. When a workable idea emerges, the research becomes more routine,
and also much easier to think about and explain to others. This is the part I have always enjoyed the
most.
Since so much of good scienceand perhaps all of great sciencehas its roots in fantasy, I
suggest that you yourself engage in a bit right now. Where would you like to be, what would you most
like to be doing professionally ten years from now, twenty years, fifty? Next, imagine that you are
much older and looking back on a successful career. What kind of great discovery, and in what field
of science, would you savor most having made?
I recommend creating scenarios that end with goals, then choosing ones you might wish to pursue.
Make it a practice to indulge in fantasy about science. Make it more than just an occasional exercise.
Daydream a lot. Make talking to yourself silently a relaxing pastime. Give lectures to yourself about
important topics that you need to understand. Talk with others of like mind. By their dreams you shall
know them.
Speaking of dreams, I once had dinner with Michael Crichton, the renowned thriller and science
fiction writer. We talked about our respective professions. The movie Rising Sun, based on his book
of the same name, had recently been released, and at the time we met it was stirring criticism over its
perceived political message. The plot was about the effort of a Japanese high-tech corporation to
expand its control in American industry by espionage and cover-up. At the time of the movies
release (1993), the Japanese economy was surging and its companies were buying pieces of America,
from Rockefeller Center to Hawaiian real estate. The overreaching theme that might be read into the
story was that Japan, having failed to build an empire through force, was now trying to build one
through economic dominance.
Crichton knew of earlier struggles over my 1975 book Sociobiology: The New Synthesis, which
created a firestorm of protest from social scientists and radical leftist writers. They were incensed by
my argument that human beings have instincts, and therefore that a gene-based human nature exists. At
times the protest reached the level of interruption of my classes and public demonstrations. One in
Harvard Square demanded my dismissal from Harvard.
Crichton asked, How did you handle all that pressure? It was embarrassing at times for me and
my family, I said, but intellectually not difficult. It was obviously a contest of science against political
ideology, and past history has shown that if the research is sound, science always eventually comes
out on top. And it did this time, in favor of sociobiology, already at the time of our dinner
conversation a well-established discipline. I suggested that the controversy over Rising Sun, which in
any case is a work of fiction, was not a bad thing. It helped to sharpen different viewpoints over an
important issue. Better to let it play out than encouraged to fester.
I took the opportunity to share with Crichton a thought experiment I had conducted that had been
stimulated by his book and the movie Jurassic Park, the latter released the same year as Rising Sun.
In Jurassic Park a billionaire hires a paleontologist and other experts to create dinosaurs for a park
he wants to set up. This being science fiction, the project of course succeeds. The method devised
was ingenious. First acquire pieces of amber formed as fossilized tree resin at the time of dinosaurs.
Some of the fragments will contain well-preserved remains of mosquitoes. That much works in
principle: Ive studied hundreds of real fossil ants in amber from the Cretaceous Period, near the end
of the Age of Dinosaurs. The next step in the plot was to find mosquitoes that still hold remnants of
blood sucked from the veins of dinosaurs. Extract the dinosaur DNA they contain, and implant it in
chicken eggs to grow dinosaurs. This is good science fiction. Each step verges on the far end of
probability even though it is almost (notice that as a scientist I say almost!) certainly impossible.
I told Crichton of a somewhat similar experiment I had imagined that was really and truly possible.
In the Harvard collection are large numbers of ants preserved in amber from the Dominican Republic,
roughly twenty-five million years in age (younger than hundred-million-year-old dinosaurs, but still
old). I had analyzed this fossil collection thoroughly and described a number of species new to
science. Among these the most abundant was one I named Azteca alpha. A living species Azteca
muelleri, which appears to be a direct evolutionary descendant or otherwise close relative of Azteca
alpha, still lives in Central America. These ants use large quantities of pheromones, acrid-smelling
terpenoids, which they release into the air to alarm nestmates whenever the colony is threatened by
invaders.
I told Crichton that I might be able to extract remnants of the pheromone from the Azteca alpha
remains, inject them into an Azteca muelleri nest, and get the alarm response. In other words, I could
deliver a message from one ant colony to another across a span of twenty-five million years. This had
Crichtons attention. He asked if I planned to do it. I said, not yet. I didnt have time, and still dont.
In this particular dream there is too much of the circus trick and too little of real sciencetoo little
chance, that is, to discover something really new.
Ill end this letter by telling you how I conceive of the creative process of both a novelist like
Crichton and a scientist. (I have been both.) The ideal scientist thinks like a poet and only later works
like a bookkeeper. Keep in mind that innovators in both literature and science are basically dreamers
and storytellers. In the early stages of the creation of both literature and science, everything in the
mind is a story. There is an imagined ending, and usually an imagined beginning, and a selection of
bits and pieces that might fit in between. In works of literature and science alike, any part can be
changed, causing a ripple among the other parts, some of which are discarded and new ones added.
The surviving fragments are variously joined and separated, and moved about as the story forms. One
scenario emerges, then another. The scenarios, whether literary or scientific in nature, compete with
one another. Some overlap. Words and sentences (or equations or experiments) are tried to make
sense of the whole thing. Early on, an end to all the imagining is conceived. It arrives at a wondrous
denouement (or scientific breakthrough). But is it the best, is it true? To bring the end safely home is
the goal of the creative mind. Whatever that might be, wherever located, however expressed, it begins
as a phantom that rises, gains detail, then at the last moment either fades to be replaced, or, like the
mythical giant Antaeus touching Mother Earth, gains strength. Inexpressible thoughts throughout flit
along the edges. As the best fragments solidify, they are put in place and moved about, and the story
grows until it reaches an inspired end.
A fire ant laying an odor trail. Drawing by Thomas Prentiss. Modified from Pheromones, by Edward O. Wilson, Scientific American
208(5): 100114 (May 1968).
Six
WHAT IT TAKES
IF YOU CHOOSE a career in science, and particularly in original research, nothing less than an enduring
passion for your subject will last the remainder of your career, and life. Too many Ph.D.s are
creatively stillborn, with their personal research ending more or less with their doctoral
dissertations. It is you who aim to stay at the creative center whom I will now specifically address.
You will commit your career, some good part of it, to being an explorer. Each advance in research
you achieve will be measured, as scientists constantly do among themselves, by completing one or
more of the following sentences:
He [or she] discovered that . . .
He [or she] helped to develop the successful theory of . . .
He [or she] created the synthesis that first tied together the disciplines of . . .
Original discoveries cannot be made casually, not by anyone at any time or anywhere. The frontier
of scientific knowledge, often referred to as the cutting edge, is reached with maps drawn by earlier
investigators. As Louis Pasteur said in 1854, Fortune favors only the prepared mind. Since he
wrote this, the roads to the frontier have greatly lengthened, and there is an enormously larger
population of scientists who travel to get there. There is a compensation for you in your journey,
however. The frontier is also vastly wider now, and it grows more so constantly. Long stretches
along it remain sparsely populated, in every discipline, from physics to anthropology, and somewhere
in these vast unexplored regions you should settle.
But, you may well ask, isnt the cutting edge a place only for geniuses? No, fortunately. Work
accomplished on the frontier defines genius, not just getting there. In fact, both accomplishments along
the frontier and the final eureka moment are achieved more by entrepreneurship and hard work than
by native intelligence. This is so much the case that in most fields most of the time, extreme brightness
may be a detriment. It has occurred to me, after meeting so many successful researchers in so many
disciplines, that the ideal scientist is smart only to an intermediate degree: bright enough to see what
can be done but not so bright as to become bored doing it. Two of the most original and influential
Nobel Prize winners for whom I have such information, one a molecular biologist and the other a
theoretical physicist, scored IQs in the low 120s at the start of their careers. (I personally made do
with an underwhelming 123.) Darwin is thought to have had an IQ of about 130.
What, then, of certified geniuses whose IQs exceed 140, and are as high as 180 or more? Arent
they the ones who produce the new groundbreaking ideas? Im sure some do very well in science, but
let me suggest that perhaps, instead, many of the IQ-brightest join societies like MENSA and work as
auditors and tax consultants. Why should the rule of optimum medium brightness hold? (And I admit
this perception of mine is only speculative.) One reason could be that IQ-geniuses have it too easy in
their early training. They dont have to sweat the science courses they take in college. They find little
reward in the necessarily tedious chores of data-gathering and analysis. They choose not to take the
hard roads to the frontier, over which the rest of us, the lesser intellectual toilers, must travel.
Being bright, then, is just not enough for those who dream of success in scientific research.
Mathematical fluency is not enough. To reach and stay at the frontier, a strong work ethic is absolutely
essential. There must be an ability to pass long hours in study and research with pleasure even though
some of the effort will inevitably lead to dead ends. Such is the price of admission to the first rank of
research scientists.
They are like treasure hunters of older times in an uncharted land, these elite men and women. If
you choose to join them, the adventure is the quest, and discoveries are your silver and gold. How
long should you keep at it? As long as it gives you personal fulfillment. In time you will acquire
world-class expertise and with certainty make discoveries. Maybe big ones. If you are at all like me
(and almost all the scientists I know are, in this regard), you will find friends among your fellow
enthusiasts and experts. Daily satisfaction from what you are doing will be one of your rewards, but
of equal importance is the esteem of people you respect. Yet another is the recognition that what you
find will uniquely benefit humanity. That alone is enough to kindle creativity, though it cannot alone
sustain it.
How hard will this be? Ill pull no punches about that part. At Harvard I advised mostly graduate
students who planned for academic careers. They chose to combine research with teaching in a
research university or liberal arts college. I posited the following time for success in this
combination: at the start, forty hours a week for teaching and administration; up to ten hours for
continued study in your specialty and related fields; and at least ten hours in researchpresumably in
the same field as your Ph.D. or postdoctoral work, or close enough to draw on the experience from
your student years. Sixty hours a week total can be daunting, I know. So seize every opportunity to
take sabbaticals and other paid leaves that allow you stretches of full-time research. Avoid
department-level administration beyond thesis committee chairmanships if at all fair and possible.
Make excuses, dodge, plead, trade. Spend extra time with students who show talent and interest in
your field of research, then employ them as assistants for your benefit and theirs. Take weekends off
for rest and diversion, but no vacations. Real scientists do not take vacations. They take field trips or
temporary research fellowships in other institutions. Consider carefully job offers from other
universities or research institutions that include more research time and fewer teaching and
administrative responsibilities.
Dont feel guilty about following this advice. University faculties consist of both inside
professors, who enjoy work that involves close social interactions with other faculty members and
take justifiable pride in their service to the institution, and outside professors, whose social
interactions are primarily with fellow researchers. Outside professors are light on committee work
but earn their keep another way: they bring in a flow of new ideas and talent and they add prestige
and income proportionate to the amount and quality of their discoveries.
Wherever your research career takes you, whether into academia or otherwise, stay restless. If you
are in an institution that encourages original research and rewards you for it, stay there. But continue
to move about intellectually in search of new problems and new opportunities. Granted that happiness
awaits those who can find pleasure while working on the same subject all their careers, and they
assuredly have a good chance of making breakthrough advances while doing so. Polymer chemistry,
computer programs of biological processes, butterflies of the Amazon, galactic maps, and Neolithic
sites in Turkey are the kinds of subjects worthy of a lifetime of devotion. Once deeply engaged, a
steady stream of small discoveries is guaranteed. But stay alert for the main chance that lies to the
side. There will always be the possibility of a major strike, some wholly unexpected find, some little
detail that catches your peripheral attention that might very well, if followed, enlarge or even
transform the subject you have chosen. If you sense such a possibility, seize it. In science, gold fever
is a good thing.
To make such success more likely, there is another quality in which you might or might not be well
endowed but if not should at least try to cultivate. It is entrepreneurship, the willingness to try
something daunting youve imagined doing and no one else has thought or dared. It could be, for
example, starting a project in a part of the world neither you nor your colleagues have yet visited; or
finding a way to try an already available instrument or technique not yet used in your field; or, even
more bravely, applying your knowledge to another discipline not yet exposed to it.
Entrepreneurship is enhanced by performing lots of quick, easily performed experiments. Yes,
thats what I just said: experiments quick and easily performed. I know that the popular image of
science is one of uncompromising precision, with each step carefully recorded in a notebook, along
with periodic statistical tests on data made at regular intervals. Such is indeed absolutely necessary
when the experiment is very expensive or time-consuming. It is equally demanded when a preliminary
result is to be replicated and confirmed by you and others in order to bring a study to conclusion. But
otherwise it is certainly all right and potentially very productive just to mess around. Quick
uncontrolled experiments are very productive. They are performed just to see if you can make
something interesting happen. Disturb Nature and see if she reveals a secret. To show you my own
devotion to the quick and sloppy, Ill give you several examples from my own initially crude efforts.
These are from memory; I didnt keep notes, careful or otherwise.
I put a powerful magnet over a column of running ants to see if I could turn their direction or at
least disrupt them, and hence detect whether ants have a magnetic sense. Time consumed: two
hours. Result: failed. The ants couldnt care less.
I sealed off the metapleural glands of ants in a laboratory colony. These tiny organs are clusters
of cells found on each side of the middle part of the body. I then let the operated ants run over
the screened roof of a culture of soil bacteria, and also over other cultures with ants not so
treated, in order to see if the metapleural glands shed airborne antibiotic substances. Time
consumed: two weeks. Result: failed. (I should have continued the effort, becoming more
persistent and using different methods. The substances are there, as subsequent researchers
showed.)
I tried to create mixed colonies of two species of fire ants by chilling them and switching their
queens. Time consumed: two hours. Result: success! I used the method to prove (with careful
experiments and neat notes this time) that the traits distinguishing the two species are due to
different genes. Chilling and mixing is now a standard technique for several lines of research.
In the 1950s, it was thought that ants probably communicate with chemical signals (later called
pheromones). But the possibility was still open that they use instead coded tappings and
strokings with their antennae. A drumbeat of antennae on the body of a nestmate, for example,
might be an alarm signal. I decided to see if I could locate the gland that produces odor trails. If
successful, I thought, that could be the first step in working out the ant pheromone code. I
dissected out all the main organs in the abdomen of worker fire ants and laid artificial trails
made from them, patiently slicing and picking under the microscope with the finest surgical
forceps. Time consumed: one week. Result: there was no response to any of the first organs
tried, but then to my surprise came a powerful response to the Dufours gland, an almost
invisible finger-shaped organ located at the base of the sting. A major success this time. Not
only did the fire ants follow the trail, they rushed out of the nest to get onto and follow it. The
Dufours secretions, it seemed, are both guides and stimulants: this was a new concept in
pheromone studies. Other scientists and I went on during the following years to work out the
dozen or so pheromone signals that compose most of the ant vocabulary.
Performing small, informal experiments is an exciting sport, and the risk in lost time is small.
However, if a preliminary procedure proves necessarily time-consuming or expensive or both, the
cost in time and money can become quickly prohibitive. If the effort fails, entrepreneurship requires
the character and the means to start overjust as it does in business and other careers outside of
science.
I will close this letter with one further piece of relevant practical advice to offer you if you are
already a graduate student or young professional. Unless your training and research commit you to a
major research facility, for example a supercollider, space telescope, or stem-cell laboratory, do not
linger too long with any one technology. When a new instrument is at the cutting edge, it may open
new horizons of research quickly, but it is also at first usually expensive and difficult to operate. As a
result, there will be a temptation for a young scientist to build a career in the new technology itself
rather than to make original studies that can be performed with it. In biochemistry and cell biology,
for example, the centrifuge has long been essential for spinning apart different kinds of molecules and
by this means making them available for physical and chemical analysis. In this way the trees can be
separated from the forest, so to speak, and by this means can make the whole forest more
understandable. At the beginning, centrifuges required a room of their own and a trained technician to
manage them. As their engineering was streamlined, however, any researcher could, with a few
instructions, run the machines alone. Then centrifuges came out of their personal laboratories in the
form of smaller, less expensive units. Today, graduate students in many fields of biology accept them
as a routine part of their tabletop armamentarium. The same progression, from technology worthy of a
discipline of its own to a routine part of every well-equipped laboratory, also occurred in the
evolution of scanning electron microscopy, electrophoresis, computers, DNA sequencing, and
inferential statistics software.
The principle I have drawn from this history is the following: use but dont love technology. If you
need it but find it at all forbiddingly difficult, recruit a better-prepared collaborator. Put the project
first and, by any available and honorable means, complete and publish the results.
At the Alabama School of Mathematics and Science (ASMS), Allison Kam (left) and Hannah Waggerman examine environmental
bacteria samples taken from the Mobile Delta. Photograph by John Hoyle.
Seven
MOST LIKELY TO SUCCEED
HOW ARE BORN SCIENTISTS best discovered? There is a growing movement to identify secondary
school students of promise and open to them special curricula that encourage talent. One example I
know about personally is the Alabama School of Mathematics and Science in my home town of
Mobile, which selects high school students from all over the state, provides them with scholarships,
and settles them in a resident college-like campus. Immersed in laboratory research guided by
experienced scientists, students learn in an atmosphere where a focus on science and technology is the
norm. Virtually all of the graduates in a given year thus far have gone straight to college.
Few scientists write memoirs, and among those who do, even fewer are willing to disclose the
emotions, urges, idols, and teachers that brought them into their scientific careers. In any case, I dont
trust most such accounts, not because the authors are dishonest, but because the scientific culture
discourages such disclosures. Scientific researchers have a hard enough time avoiding any utterance
that might sound childish, poetic, or dilatory and insubstantial to other scientists. Hence a leathery,
just-the-facts style confines most personal accounts of scientific discovery, and a good story often
comes out reticent and dull. False modesty is the peccadillo of the scientific memoirist.
An example (imaginary) might read as follows: While working at the Whitehead Institute X-ray
crystallography laboratory on avian muscle protein, I became fascinated with the classical problem of
autonomous folding. I was led to consider . . .
Well, Im sure that such writers in real life were fascinated and even compelled to consider this or
that, but not me reading their account. A reader would like to know the reason why they did the hard
work to achieve their goal. Where was the adventure, what was the dream?
So there is a great deal we dont know about what makes scientists, and how they really feel about
their work. Without the Alabama School of Mathematics and Science, would the elite students there
all have gone to college and careers related to science?
Another question is whether it is more inspiring and useful for such students to work in small teams
or on individual projects that each selects, however idiosyncratic. We have no clear answer to either
of these questions. But I have no doubt that encouragement given teenagers who are already
predisposed to scientific careers does help lead them to success in later years.
Basically this question about teams arises in the encouragement of innovation by practicing
scientists. The conventional wisdom holds that science of the future will be more and more the
product of teamthink, multiple minds put in close contact. It is certainly the case that fewer and
fewer solitary authors publish research articles in premier journals such as Nature and Science. The
number of coauthors is more often three or more; and in the case of a few subjects, such as
experimental physics and genome analysis, where research by necessity involves an entire institution,
the number sometimes soars to over a hundred.
Then there are the vaunted science and technology think tanks, where some of the best and brightest
are brought together explicitly to create new ideas and products. Ive visited the Santa Fe Institute in
New Mexico, as well as the development divisions of Apple and Google, two of Americas
corporate giants, and I admit I was very impressed with their futuristic ambience. At Google I even
commented, This is the university of the future.
The idea in these places is to feed and house very smart people and let them wander about, meet in
small groups over coffee and croissants, and bounce ideas off each other. And then, perhaps while
strolling through well-manicured grounds or on their way to a gourmet lunch, they will experience the
flash of epiphany. This surely works, especially if there is a problem in theoretical science already
well formulated, or else a product in need of being designed.
But is groupthink the best way to create really new science? Risking heresy, I hereby dissent. I
believe the creative process usually unfolds in a very different way. It arises and for a while
germinates in a solitary brain. It commences as an idea and, equally important, the ambition of a
single person who is prepared and strongly motivated to make discoveries in one domain of science
or another. The successful innovator is favored by a fortunate combination of talent and circumstance,
and is socially conditioned by family, friends, teachers, and mentors, and by stories of great scientists
and their discoveries. He (or she) is sometimes driven, I will dare to suggest, by a passive-
aggressive nature, and sometimes an anger against some part of society or problem in the world.
There is also an introversion in the innovator that keeps him from team sports and social events. He
dislikes authority, or at least being told what to do. He is not a leader in high school or college, nor is
he likely to be pledged by social clubs. From an early age he is a dreamer, not a doer. His attention
wanders easily. He likes to probe, to collect, to tinker. He is prone to fantasize. He is not inclined to
focus. He will not be voted by his classmates most likely to succeed.
When prepared by education to conduct research, the most innovative scientists of my experience
do so eagerly and with no prompting. They prefer to take first steps alone. They seek a problem to be
solved, an important phenomenon previously overlooked, a cause-and-effect connection never
imagined. An opportunity to be the first is their smell of blood.
On the frontier of modern science, however, multiple skills are almost always needed to bring any
new idea to fruition. An innovator may add a mathematician or statistician, a computer expert, a
natural-products chemist, one or several laboratory or field assistants, a colleague or two in the same
specialtywhoever it takes for the project to succeed becomes a collaborator. The collaborator is
often another innovator who has been toying with the same idea, and is prone to modify or add to it. A
critical mass is achieved and discussion intensifies, perhaps among scientists in the same place,
perhaps scattered around the world. The project moves forward until an original result is achieved.
Group thought has brought it to fruition.
Innovator, creative collaborator, or facilitator: in the course of your successful career, you may
well fill each of these roles at one time or another.
The author with sweep net looking at insects: Mobile, Alabama, 1942 (left), and the summit of Gorongosa Mountain, Mozambique, 2012
(right). Photographers: 1942, Ellis MacLeod; 2012, Piotr Naskrecki.
Eight
I NEVER CHANGED
APPROACHING THE END of more than sixty years of research, I have been fortunate to have been given
complete freedom in choosing my subjects. Because I no longer look to very much in the way of a
future, and the fires of decent ambition have been accordingly damped, I can tell you, without the
debilitating drag of false modesty, how and why some of my discoveries were made. Id like you to
think, as I thought early in my career of older scientists, If he could do it, so can I, and maybe
better.
I started very young, even before my snake-handling triumph in Camp Pushmataha. Maybe you
started young too, or else you are young and just starting. Back in 1938 when I was nine years old, my
family moved from the Deep South to Washington, D.C. My father was called there for a two-year
stint as an auditor in the Rural Electrification Administration, a Depression-era federal agency
charged with bringing electric power to the rural South. I was an only child, but not especially lonely.
Any kid that age can find a buddy or fit into some small neighborhood group, maybe at the risk of a
fistfight with the alpha boy. (For years I carried scars on my upper lip and left brow.) Nevertheless, I
was alone that first summer and was left to my own devices. No stifling piano lessons, no boring
visits to relatives, no summer school, no guided tours, no television, no boys clubs, nothing. It was
wonderful! I was enchanted at this time by Frank Buck movies Id seen about his expeditions to
distant jungles to capture wild animals. I also read National Geographic articles that told about the
world of insectsbig metallic-colored beetles and garish butterflies, also mostly from the tropics. I
found an especially absorbing piece in a 1934 issue entitled Ants, Savage and Civilized, which led
me to search for these insectssearches that were always successful due to the overwhelming
abundance of ants everywhere I looked.
There were postage stamps to collect and comic books, of course, but also butterflies and ants.
Nothing complicated about collecting and studying insects. For a while anyway, they served as my
lions and tigers, not exactly big game snared in nets by a hundred native assistants, but nevertheless
the real thing. Thus fired up, I put some bottles in a cloth bag and walked over to the nearby woods of
Rock Creek Park on my first expedition, venturing into second-growth deciduous woodland
crisscrossed by paths. I remember vividly the animals I brought home that day. They included a wolf
spider and the red and green nymph of a long-horned grasshopper.
Subsequently I decided to add butterflies as my quarry. My stepmother made me a butterfly net. (I
put together a lot of them in the years to follow. In case you would like to do the same, bend a wire
coat hanger into a circular loop, straighten the hook, heat the hook until it can burn wood, then push it
into the end of a sawed-off broomstick. Finally, sew a net of cheesecloth or mosquito netting around
the hoop.)
Thus accoutered, my butterfly collection grew furiously. Early in this career of mine, my best
friend Ellis MacLeod, who years later was to be a professor of entomology at the University of
Illinois, told me he had seen a medium-sized butterfly, black with brilliant red stripes across both
wings, fluttering back and forth around the bushes in front of his apartment building. We found a book
on butterflies and identified it as Red Admiral. The book was the beginning of my library on insects.
At this point my mother, living with her second husband in Louisville, Kentucky, sent me a larger,
beautifully illustrated book on butterflies. It threw me into confusion. The only familiar species I
found in it was the Cabbage White, a species accidentally introduced from Europe many years
previously. The reason for my confusion, I learned later, was the book was about British butterflies.
My future was set. Ellis and I agreed we were going to be entomologists when we grew up. We
delved into college-level textbooks, which we could scarcely read, although we tried very hard. One
that we checked out from a public library and worked on page by page was Robert E. Snodgrasss
formidable Principles of Insect Morphology, published in 1935. Only later did I learn that grown-up
biologists were using it as a technical reference book. We visited the insect collections on display at
the awesome National Museum of Natural History, aware that professional entomologists were
curators there. I never saw one of these demigods (one was Snodgrass himself), but just knowing they
were there as part of the United States government gave me hope that one day I might ascend to this
unimaginably high level.
Returning in 1940 with my family to Mobile, I plunged into the rich new fauna of butterflies. The
semitropical climate and nearby swamps were a close realization of my earlier dreams. To the red
admirals, painted ladies, great spangled fritillaries, and mourning cloaks characteristic of the more
northern climes I added snout butterflies, Gulf fritillaries, Brazilian skippers, great purple
hairstreaks, and several magnificent swallowtailsgiant, zebra, and spicebush.
Then I turned to ants, monomaniacally determined to find every kind living in the weed-grown
vacant lot next to our large family house on Charleston Street. I didnt know the scientific names of
the species, but I do now, and the location of every colony in the quarter-acre space is vivid in my
memory: the Argentine ant (Linepithema humile), which nested in the rotting wooden fence at the
edge of the lot in the winter and spread out among the weeds during the warm months; large black ants
(Odontomachus brunneus) with snapping jaws and vicious stings, which inhabited a pile of roof
shingles at the far corner beneath a fig tree; a huge mound-dwelling colony of the red imported fire ant
(Solenopsis invicta) that I found at the edge of the lot next to the street; and a colony of a tiny yellow
species (Pheidole floridana) nesting beneath an old whiskey bottle.
Three years later, as nature counselor at Pushmataha, I transitioned into a snake period, and began
catching as many as I could find of the dozens of species that inhabit southwestern Alabama.
Ive gone into this boyhood story to make a point that may be relevant to your own career
trajectory. I have never changed.
Planned path of the Mars rover Curiosity in Gale Crater. NASA picks Mars landing site, by Eric Hand, Nature 475: 433 (July 28,
2011). Modified from photograph by NASA/JPL-CALTECH/ASU/UA.
Nine
ARCHETYPES OF THE SCIENTIFIC MIND
THE BETTER EMOTIONS of our nature are felt and examined and understood more deeply during
maturity, but they are born and rage in full intensity during childhood and adolescence. Thereafter
they endure through the rest of life, serving as the wellsprings of creative work.
I told you earlier that during the earliest steps to discovery the ideal scientist thinks like a poet.
Only later does he work at the bookkeeping expected of his profession. I spoke of passion and decent
ambition as forces that drive us to creative work. The love of a subject, and I say it again for
emphasis, is meritorious in itself. By pleasure drawn from discovery of new truths, the scientist is
part poet, and by pleasure drawn from new ways to express old truths, the poet is part scientist. In
this sense science and the creative arts are foundationally the same.
I could say more to you about the metaphorical temple of science, could speak of its infinite
chambers and galleries, could offer you additional instructions on how to find your way. But you will
learn all that on your own as you progress. Better at this point to explore with you some of the
psychology of innovation. I suggest that you examine your inner thoughts in broader terms to locate the
kinds of satisfaction you might obtain from a career in science. The value of this exercise in self-
analysis applies equally well to professions in research, teaching, business, government, and the
media.
Psychologists have identified five components in personality, partly based on differences in genes,
on which the inner lives of people are based. My impression is that research scientists are more
prone to introversion as opposed to extroversion, are neutral (can go either way) to antagonism
versus agreeableness, and lean strongly toward conscientiousness and openness to experience. The
circumstances in their lives that bend them toward creative work vary enormously, and the events that
spark their interest in particular research opportunities differ by at least as much.
Nevertheless, I will repeat my conviction that you will become most devoted to research in science
and technology through images and stories that have affected you earlyparticularly from childhood
to the fringes of post-adolescence, say from nine or ten years of age through the teenage years into the
early twenties. Further, the transformative events can be classified into a relatively small number of
general images that carry maximum long-term impact. I will call them archetypes, believing they are
comparable to the imprinting that makes it easier to learn languages and mathematics at a relatively
early age. Archetypes, as scholars have noted, are commonly expressed by stories in myth and the
creative arts. They are also powerfully manifested in the great technoscientific enterprise. It will
make a difference in your own creative life if you are moved by one or more.
THE JOURNEY TO AN UNEXPLORED LAND. This yearning takes a variety of forms: to search for an
unknown island; to climb a distant mountain and look beyond; to journey up an unexplored river; to
contact a tribe rumored to live there; to discover lost worlds; to find Shangri-la; to land on another
planet; to settle and start life anew in a distant country.
In science and technology, this archetype is expressed variously in the urge to find new species in
unexplored ecosystems; to map the microscopic structure of the cell; to locate unsuspected
pheromones and hormones that link organisms and tissues together; to view the deepest part of Earths
seafloor; to travel along and map the contours of the tectonic plates and canyons; to peer on through
inner Earth to the core; to see the outer boundary of the universe; to discover signs of life on other
planets; to listen for alien messages on the SETI telescopes; to find ancient organisms in fossils that
date back to the beginning of life on Earth; and to uncover the remains of our prehuman ancestors and
thereby disclose at long last where we came from and what we are.
SEARCH FOR THE GRAIL. The grail exists in many forms: the powerful formula (or talisman) known
to the ancients but lost or kept secret; the Golden Fleece; the symbol of the secret society; the
philosophers stone; the path to the center of Earth; the incantation that releases evil spirits; the
formula for enlightenment of mind and transcendence of soul; the hidden treasure; the key that unlocks
the otherwise unassailable gate; the fountain of youth; the rite or magical potion that confers
immortality.
Proceeding to the real world and the goals of science, we find equivalents that rouse the spirit in a
similar manner. The grail is the discovery of a new and powerful enzyme or hormone; breaking the
genetic code; discovering the secret of the origin of life; finding evidence of the first organism that
evolved; the creation of a simple organism in the laboratory; the attainment of human immortality;
achieving controlled fusion power; solving the mystery of dark matter; detecting neutrinos and the
Higgs boson; deducing wormholes and multiverses.
GOOD AGAINST EVIL. Our stronger myths and emotions are driven by war against alien invaders; the
conquest of new lands by our own people (who of course we regard as the civilized, the virtuous, the
godly, and the chosen against the savages opposing us); the war of God against Satan; the overthrow
of an evil tyrant; the triumph of the Revolution against all odds; the Hero, the Champion, or the Martyr
vindicated in the end; the inner struggle of conscience between right and wrong; the Good Wizard; the
Good Angel; the Magical Force; arrest and punishment of the criminal; vindication of the whistle-
blower.
In the real world of science, we are aroused by what we call the war against cancer; the fight
against other deadly diseases; the conquest of hunger; the mastery of a new energy source that can
save the world; the campaign against global warming; forensic DNA sequencing to capture a
criminal.
These several archetypes resonate up from the deep roots of human nature. They are appealing and
easily understood. They convey meaning and power to humanitys creation myths. They are retold in
the epic stories of history. They are the themes of great dramas and novels.
Cell-surface receptor activated by a signaling molecule (agonist, top) turns on a G-protein-coupled receptor that activates the G protein (3
Gs, lower half). Brian Kobilka.
Ten
SCIENTISTS AS EXPLORERS OF THE UNIVERSE
THE EXPLORERS CLUB of New York was founded in 1904 to celebrate the geographical exploration
of the world and (later) outer space. Over the years the roster has included Robert Peary, Roald
Amundsen, Theodore Roosevelt, Ernest Shackleton, Richard Byrd, Charles Lindbergh, Edmund
Hillary, John Glenn, Buzz Aldrin, and other famous adventurers of the twentieth century. The
headquarters of the Explorers Club on East Seventieth Street are stuffed with archives and
memorabilia of the worlds great wanderers. Also kept there are the famous expedition flags, carried
over decades by members who journey to distant and sometimes virtually inaccessible destinations.
When the explorer returns, so does the flag, along with an account of what was discovered.
Each year an annual dinner is held by the club at the Waldorf Astoria, a grand edifice evoking an
era of great wealth. Dress is formal, and attendees are urged to wear whatever medals they have
received in past exploits. It is the only occasion of which I am aware in North America where the
latter embellishment is practiced. At dinner the excess of display turns to merriment. For years, until a
guest became ill at one of the dinners, the fare was a humorous sample of what the explorer might be
forced to eat when supplies run out: candied spiders, fried ants, crispy scorpions, broiled
grasshoppers, roasted mealworms, exotic fish, and wild game.
In 2004 I was elected an honorary member, a distinction given only a score of men and women, and
in 2009 I received the Explorers Club Medal, the highest award. At first this might be seen as an
entirely inappropriate honor, and maybe it was. I had never suffered privation on polar ice, never
climbed an unconquered Antarctic mountain, never contacted a previously unknown Amazonian tribe.
The reason was science. The board of the Explorers Club had decided to expand its concept of what
remains left to explore on our planet. The conventional map of the world had been largely filled in
since the time Teddy Roosevelt traveled down an unnamed river in the Amazon and Robert Peary and
Matthew Henson conquered the North Pole. Most of Earths land surface had been visited on foot or
by helicopter. What remained could be examinedeven monitored day by daythrough satellites to
the last square kilometer. What was left of importance to map on the home planet other than the deep
sea? The answer is its little-known biodiversity, that variety of plants, animals, and microorganisms
that compose the thin layer of Earth called the biosphere. Although most of the flowering plants,
birds, and mammals have been found, described, and given a scientific name, the great majority of
species in other groups of organisms still remained to be discovered. Biologists and naturalists, both
professional and amateur, who set out to find species and map the biosphere, have remained as among
Earths true explorers.
At the dinner in 2009 on which biodiversity was officially added to the worthy unknown, I had the
extraordinary experience of giving the main address. There was much to be excited about that
evening, but the memory that first comes to my mind was meeting the son of Tenzing Norgay, who in
1951, with Edmund Hillary, first summited Mount Everest. I reminded him that upon his return from
the mountain, when a journalist had asked Tenzing Norgay, How does it feel to be a great man? he
responded, It is Everest that makes men great. To which I may add, to young biologists in particular
who dream of combining science with physical adventure, it is the biosphere that offers you
opportunities of epic proportion.
On Monday, July 3, 2006, the Explorers Club conducted its first expedition to explore
biodiversity. It joined the American Museum of Natural History and other local nature-oriented
organizations to conduct a bioblitz in New York Citys Central Park. Bioblitzes are events in which
experts on every kind of organism, from bacteria to birds, gather to find and identify as many species
as possible during a stated short period of time, usually twenty-four hours. The aim on that day was to
introduce the public to the concept that even a much-tramped-over urban area teems with the diversity
of life. At the end of the day, the 350 registered volunteers had talliedand mind you, this was in
New York City836 species, including 393 plants and 101 animals, the latter including 78 moths, 9
dragonflies, 7 mammals, 3 turtles, 2 frogs, and 2 microscopic, caterpillar-like tardigrades, the last
enigmatic and seldom studied anywhere in the world. The tardigrades were the first ever reported
from Central Park. One of the frogs was later determined to be a species new to science and found
only in and around New York City.
On Tuesday, July 8, 2003, for the first time during any bioblitz, samples of soil and water were
collected for later analysis of bacteria and other microorganisms, the most abundant and diverse of
all forms of life. There was even physical adventure of a sort. Sylvia Earle, a leading marine
biologist renowned for her dives in oceans around the world, offered to explore the murky slime-
filled waters of the small lake next to the Bethesda Fountain, in order to add aquatic creatures to our
list. While I have had no concern, she observed, about diving with sharks and killer whales or
other creatures in the ocean, I did have reason to be mighty fearful of the microbes in the green pond
in Central Park. She and others brave enough to dive with her produced a substantial list of species.
There was one uncertain identification. I found a snail floating by, Earle reported. But Im not sure
if it was a resident or if it was introduced by the nearby restaurant as an escargot.
Very few places remain on Earth that are not seething with species of plants, animals, or
microorganisms. At this time, for all intents and purposes the biological diversity seems almost
infinite; and each living species in turn offers scientists boundless opportunities for important original
research.
Consider a rotting tree stump in a forest. You and I casually walking past it on a trail would not
give it more than a passing glance. But wait a moment. Walk around the stump slowly, look at it
closelyas a fellow scientist. Before you, in miniature, is the equivalent of an unexplored planet.
What you can learn from the decaying mass depends on your training and the science you have chosen
to begin your career. Choose a subject, draw on it from anywhere in physics, chemistry, or biology.
With imagination you will conceive original research programs that can be centered on the rotting
stump.
Lets think about this more together. By research specialization I am a student of ecology and
biodiversity. So join me in those overlapping domains of science, and lets ask: What life exists in
the stump microplanet?
Start with animals. There may be cavities in the side, or at the base or beneath the roots, large
enough to hold a mouse-sized mammal, and if not, surely a frog, salamander, snake, or lizard. Let us
next magnify the image to bring in insects and other invertebrates one millimeter to thirty millimeters
in length. We can see most of them with unaided vision. They are each distributed according to niches
for which millions of years of evolution have adapted them. A large minority are insects. An
entomologist trained in taxonomy (as should also be the case for any other scientist who needs to tell
one species from another) will point out beetles that live heremembers of the taxonomic families
Carabidae (common name: ground beetles), Scarabaeidae (scarabs), Tenebrionidae (darkling
beetles), Curculionidae (weevils), Scydmaenidae (antlike stone beetles), and several others. More
species of beetles are known than any other comparable group of organisms in the world. Yet even
though the most diverse, they are not the most abundant in individuals. If the stump is well along in
decomposition, ant colonies will be there, resting in the frass beneath the bark and among the roots
below. Termites may riddle the heartwood. In the crevice and over the surface can be found bark lice,
springtails, proturans, fly and moth larvae, earwigs, japygids, and symphylans. Around them a myriad
of other rotting-stump invertebrates other than insects: crustacean pill bugs, tiny annelid worms,
centipedes of varying sizes and shapes, slugs, snails, pauropods, and a huge fauna of mites, the
numbers of the latter dominated by sluggish spherical oribatids with a sprinkling of wolfish, fast-
running phytoseiids. Spiders of many kinds spin webs or hunt widely on foot.
In patches of moss and lichens that grow on the surface of the stumplittle worlds of their own
roam the aforementioned tardigrades, also called bear-animalcules for their body shape midway
between caterpillars and miniature bears. Among these animals are the most abundant of all: the
nematodes, also called roundworms, most barely visible. Worldwide, roundworms are reckoned to
make up four-fifths of all the individual animals.
If my staccato listing confuses you, like a page torn from a telephone book, rest assured it also
confuses most biologists as well, and yet it is only the beginning of a very long roster that could be
called out from our stump.
Throughout the decaying wood, fungal strands penetrate, the hyphae hanging in gossamer strands
when the bark is pulled free. Microscopic fungi abound wherever there is moisture. Ciliates and other
protistans swim in films and droplets of water.
All of the life of the stump ecosystem is dwarfed, however, in both variety and numbers of
organisms, by the bacteria. In a gram of detritus on the surface or soil beneath the stumps base exist a
billion bacteria. Together this multitude represents an estimated five thousand to six thousand species,
virtually all unknown to science. Still smaller and likely even more diverse and abundant (we dont
know for sure) are the viruses. To give you a sense of relative size at this lowest end of the stump-
world scale, think of one cell of a multicellular organism as the size of a small city. A bacterium
would then be the size of a football field and a virus the size of a football.
Yetall of this ensemble, as we pause next to it for an hour or a day, is no more than a snapshot.
Across a period of months and years, as the stump decays further, there is a gradual change of
species, the numbers of organisms in each species, and the niches they fill. During the transition, new
niches open and old ones close as the stump evolves from hard fresh-cut wood leaking resin to rotting
splinters leaking nutrients into the soil. Finally, the stump becomes no more than crumbled fragments
and mold, infiltrated by roots of invading neighbor plants and covered by dead twigs and leaf litter
fallen from the canopy of the trees above. Throughout, the stump is a miniature ecosystem.
At each stage of decomposition, the stumps fauna and flora have been changing. In each cubic
centimeter of its living and inert mass, the system has been passing energy and organic matter back
and forth to the surrounding environment.
What could you make of this special world, should you choose to become an ecologist or
biodiversity scientist and study it? How would you and your fellow researchers encompass the nearly
infinite variations in Earths biosphere represented by this microcosm? So much has been written, yet
so very little is knowneven the full census of stump-dwelling species and those of countless other
kinds of miniature ecosystems on the land and in the sea remain unknown, unrecorded, unwritten.
Drastically less has been learned of the lives and roles of each of the species in turn. Their combined
order and process exceeds everything of which we have knowledge in the rest of the universe.
Keep in mind that a distinguished career of scientific research can be built from any one of the
species, by means of contributions to different disciplines within biology, chemistry, and even
physics. Karl von Frisch, the great German entomologist who made many discoveries concerning the
honeybee, including their symbolic waggle-dance communication and their remarkable memory of
place, knew that he had only begun to explore the biology of this single insect species. The honeybee
is like a magic well, he said. The more you draw, the more there is to draw.
III
A LIFE
in
SCIENCE
The face of a dacetine ant, Strumigenys cordovensis. Collected by Stefan Cover in Cuzco Amazonico, Peru. Imaged by Christian
Rabeling.
Eleven
A MENTOR AND THE START OF A CAREER
AS A CALLOW, severely undereducated eighteen-year-old student at the University of Alabama, I
began a correspondence with a Ph.D. student at Harvard University named William L. Brown.
Although only seven years my senior, Bill was already a leading world authority on ants. At that time
there were only about a dozen experts on ants worldwide and he was one of them, not counting those
who specialized on the control of pest species.
The most inspiring thing about Bill Brown was his devotion bordering on fanaticismto science,
to entomology, to jazz, to good writing, and to ants, in that rising order. He was, as I wrote of him in a
1997 memorial tribute, a working-class guy with a first-rate mind. He visited bars, enjoyed beer,
dressed poorly by the stiff standards of the Harvard of his day, and mocked pretense whenever he
encountered it in the faculty. But he was a godsend to the boy he befriended.
Wilson, he wrote his teenage follower, youve made a good start with your project of
identifying all the species of ants found in Alabama. But its time to get serious about a more basic
subject, where you can do original work in biology. If youre going to study ants, get serious.
Bill, when I first came to know him, was at that time absorbed in classifying a group of species
called the dacetine ants, limited mostly to the tropics and parts of the warm temperate zone. These
insects are easily distinguished by their bizarre anatomy. Their jaws are long and hooked at the end
and lined with needlelike teeth. Their bodies are clothed in various combinations of curly or paddle-
shaped hairs; and, in many of the species, a spongy mass of tissue encircles the waist.
Wilson, Bill went on, there are a lot of species of dacetines in Alabama. I want you to collect
as many colonies for our studies as you can, and while youre at it, find out something about their
behavior. Almost nothing has been done on that subject. We dont even know what they eat.
I liked the way Bill Brown addressed me as a colleague, albeit one in training, like a sergeant
instructing a private. If we had been in the U.S. Marines, I suppose I would have followed him to hell
and backor something like that, assuming there are ants living somewhere in hell. In spite of my
young age and lack of experience, he expected me to behave as a professional entomologist. He
insisted that I just get out there and get the job done. There was no hint of get in touch with your
feelings or think about what youd most like to do.
So, pumped up with his confidence in me, I got out there and got the job done. I began by molding a
series of plaster-of-Paris boxes with cavities the size of those that wild colonies occupy in nature. I
added a larger adjacent cavity where the ants could hunt for prey. Into many such cavities I placed
live mites, springtails, insect larvae, and a wide variety of other invertebrates I found around the
nests of dacetines in natural habitats. I was later to label this the cafeteria method.
My efforts were rewarded quickly. The little ants, I discovered, prefer soft-bodied springtails
(technically, entomobryoid collembolans). As I watched them stalk and capture these prey, the odd
anatomy of the dacetine ants made perfect sense. Springtails are abundant around the world in soil
and leaf litter, and in some localities they are among the dominant insects. But ordinary predators
such as ants, spiders, and ground beetles find them very difficult to catch. Beneath the body of each is
a long lever that can be sprung violently but most of the time is locked in placein other words,
constructed like a mousetrap. When the springtail is disturbed even slightly, it pulls an anatomical
trigger and the lever is released. Slamming against the ground, the lever catapults the insect high into
the air. The equivalent acrobatic feat in a human being would be a leap of twenty yards up and a
football-field distance forward.
The high jump works well against most predators, but the dacetine ant is built to defeat it. Upon
sensing a springtail close by with the sensory receptors in her antennaeshe is mostly blindthe
huntress throws her long mandibles open, in some species 180 degrees or more, and locks them in
place with a pair of movable catches on the front of the head. The huntress then slowly stalks the
prey, literally step by cautious step. In the presence of a springtail, she is one of the slowest ants in
the world. Her antennae wave side to side, also slowly, fixed on the location of the prey, turning to
the right when the odor grows faint on the left, and to the left when the odor grows faint on the right,
keeping the ant on track. Two long sensitive hairs project from the stalkers upper lip. When their tips
touch the springtail, the catch is pulled down, releasing the powerful muscles that strain at the base.
The mandibles slam shut, driving the needle-sharp teeth into the soft body of the springtail. Often the
prey is able instantaneously to release its abdominal lever, throwing it and the ant spinning into the
air. Ive often thought that if dacetine ants and springtails were the size of lions and antelopes, they
would be the joy of wildlife photographers.
From my and Bill Browns early studies, various of which we published singly or together, a first
picture of dacetine biology emerged. First, physiologists came to realize that the closing of the
mandibles is one of the fastest movements that exist in the animal kingdom. Also the spongelike collar
around the dacetines waist was discovered by later researchers to be the source of a chemical that
attracts springtails, drawing them closer to the mandibular snare.
In time we and other entomologists came to recognize the dacetines as among the most abundant
and widely distributed of all ant groups. Although their tiny size makes them inconspicuous in the soil
and litter, they are an important link of the food chains of the worlds habitats. And, incidentally,
colonies of many species live in rotting stumps like the one I described earlier.
During the next decade, Bill Brown and I took the next logical step into evolutionary biology.
Armed with growing information, we reconstructed the changes in dacetines across millions of years,
as they spread around the world and their species multiplied. In what manner and under what
conditions, we asked, have the different species grown or shrunk in anatomical size? How and why
did some of them evolve to build their nests in the soil and others in fallen twigs on the ground, or in
rotting logs and stumps? A few, we learned, are even specialized to live in the root masses of orchids
and other epiphytes of the rain forest canopy.
The history of the dacetine ants came into focus as we continued our studies. It turned out to be an
evolutionary epic comparable to that of all the kinds of antelopes, for example, or all of the rodents,
or all of the birds of prey. You may think that ants like these, being so small, must also be unimportant
and deserving of less attention. Quite the contrary. Their vast numbers and combined weight more
than make up for their puny individual size. In the Amazon rain forest, one of the worlds strongholds
of biological diversity and massed living tissue, ants alone weigh more than four times that of all the
land-dwelling vertebratesmammals, birds, reptiles, and amphibianscombined. In the Central and
South American forests and grasslands alone, one taxonomic group of ants, the leafcutters, collect
fragments of leaves and flowers on which they rear fungi for food, making them the leading consumers
of vegetation. In the savannas and grasslands of Africa, mound-building termites also rear fungi and
are the primary animal builders of the soil. Although insects, spiders, mites, centipedes, millipedes,
scorpions, proturans, pillbugs, nematodes, annelid worms, and other such lilliputians are ordinarily
overlooked, even by scientists, they are, nonetheless the little things that run the world. If we were
to disappear, the rest of life would flourish as a result. If on the other hand the little invertebrates on
the land were to disappear, almost everything else would die, including most of humanity.
Because as a boy I dreamed of exploring jungles in order to net butterflies and turn over stones to
look for different kinds of ants, I followed by happenstance the advice I gave you earlier: go where
the least action is occurring. Just by any small twist of fate, I might easily have joined the large
population of young biologists working on mice, birds, and other large animals. Like most of them, I
would have enjoyed a productive and happy career in research and teaching. Nothing wrong with that
at all, but by following the less conventional path, and by having an inspiring mentor like Bill Brown,
I had a far easier time of it. I discovered early the special opportunity to conduct scientific research
in rotting stumps and other microcosms that make up the foundation of the living world, but which
then and to this day remain so easily passed by.
Martialis heureka, the most primitive known living ant. Modified from drawing by Barrett Klein, Biology Department, University of
WisconsinLa Crosse (www.pupating.org).
Twelve
THE GRAILS OF FIELD BIOLOGY
TRACKING THE HISTORY of the dacetine ants, Bill Brown and I came to focus on what appears to be
the most primitive living species, similar to the ancestral species that long ago gave rise to the
worldwide tribe of dacetines alive today. Our quarry was Daceton armigerum, a big insect as ants
go, roughly the same size as the half-inch-long carpenter ants found everywhere in the north temperate
zone. Covered with spines, its long jaws flat and armed at the tip by sharp spines, it was known to
occur on trees in the rain forests of South America. Otherwise, entomologists had almost no
information on where it nests, the social structure of its colonies, how and when it forages, and the
kind of prey it hunts. It became, for a short while at least, my personal grail.
Very early in my ant-hunting world travels, I arrived in Suriname, at that time known as Dutch
Guiana. I went immediately into the rain forests around the capital city of Paramaribo to search for
the big dacetine. After a week of sweat-soaked work and failure, I enlisted the help of resident
entomologists. They in turn sent forth their assistants and a few other forest-savvy locals who had
seen the ant and had a good idea where to look. Soon a colony was found. It was where I had not
lookedin a small tree growing in a dense, seasonally flooded swamp. We cut the tree down and
carried it in segments to a laboratory in Paramaribo. There I carefully and lovingly sliced open the
trunk, revealing a cavity in which the entire colony livedqueen, workers, brood, and all. Studying it
(and, later, a second colony I found in Trinidad), I filled in the blank spaces: The colonies are
composed of several hundred workers; the foragers go out singly to search for prey in the canopy;
each worker hunts on its own, catching insects of a wide variety, all of which are larger than
springtails and other prey sought by smaller known dacetines. And more.
It is common for biologists to make a scan of biodiversity in order to locate some especially
promising species or other, like the primitive giant dacetine, that offers opportunities to make a
discovery of unusual importance. Another expedition I launched with the same goal in mind was to
Ceylon, now known as Sri Lanka. The aneuretine ants found there I knew to be as distinctive a group
as the dacetine ants. Unlike dacetines, however, aneuretines are not among the dominant insects of the
world at the present time. In fact, they are on the edge of extinction. Their high moment in the
evolutionary sweepstakes came long ago, toward the end of the Mesozoic Era, the Age of Reptiles,
and continued on for a while into the early Cenozoic Era, the Age of Mammalsin other words a
hundred million to fifty million years ago. We knew from fossil remains that aneuretines were both
diverse and relatively common during the latter period. But of their social organization, their nests,
their colonies, their communication, their food habits, we knew nothing. When I was a young
researcher at Harvard, I was aware that in the late 1800s two specimens of a living species,
Aneuretus simoni, had been collected in the six-hundred-year-old Royal Botanical Gardens in
Peradeniya near Kandy, in the center of Sri Lanka. But no other specimens of the small dark-yellow
ant had found their way into collections since that time.
Was the last living aneuretine species extinct? Had it gone the way of the dodo and Tasmanian
wolf during such a brief interval of time, after tens of millions of years of life? I felt compelled to
find out. Another grail! In 1955, at the age of twenty-five, I disembarked from an Italian passenger
ship at Colombo and went straight to the Udawattakele, the forested pleasure garden of the kings at
Kandy, which seemed to be the most promising semi-natural site. For a week I searched throughout
the daylight hours. I came up with nothing, not even one stray aneuretine worker. I then proceeded to
the more disturbed grounds of the Peradeniya gardens, the source of the original specimens. More
close searching, still no Aneuretus. It seemed indeed possible that the species I sought, and with it the
great evolutionary assemblage of the aneuretine ants, might really be gone.
But this verdict was unacceptable to me. So I traveled south to Ratnapura, resolved to hunt for the
ant out from the city and into the nearby rain forest, which at that time stretched almost continuously to
Adams Peak.
Upon arriving in Ratnapura, I checked into a rest house, washed up, and within the hour strolled
over to a nearby reservoir, where, although the shore was torn up by pedestrians and grazing cattle, I
had noticed a thin grove of trees. I idly picked up a hollow twig lying on the ground and snapped it in
two, expecting nothing much of interest to be living inside. Instead, I was stunned when out poured a
stream of angry Aneuretus. I stood there staring at this wonderful gift. I paid no attention to the
irritating sensation of the workers pouring over my hands. Would an Audubon scholar, in comparison,
be bothered by a paper cut upon discovering a new original folio?
The next day, elated as I supposed only an entomologist can be, I took a bus inland to a stop close
to the edge of the nearby rain forest. I was accompanied by an assistant assigned to me by the Museum
of Natural History in Colombo. His principal role was to assure local Jainists, whose religion
forbids the killing of all animal life even down to the lowly ants, that I had been allowed a
dispensation. Along a forest trail I soon found several more Aneuretus colonies. I studied them in the
field, during intervals between occasional pounding downpours of rain. Several colonies I placed in
artificial nests to study their communication, care of the young and mother queen, and other aspects of
their social behavior. Back at Harvard, I worked with several colleagues to describe the aneuretine
internal anatomy.
Almost thirty years later, as a Harvard professor, I directed an undergraduate student from Sri
Lanka, Anula Jayasuriya, as she made further surveys of the aneuretines for her senior honors thesis.
She found that the range of the species was shrinking, which was no surprise due to the relentless
clearing of Sri Lankas lowland forest since the time of my visit. At this point I had Aneuretus simoni
put on the list of endangered species compiled by the International Union for the Conservation of
Nature, one of the few rare insect species well enough known even to be considered for this category.
During this period, the picture of the evolution of the small but world-dominant ants as a whole
was coming into focus. More researchers were entering the study of fossil and living species. We
were filling in the steps in evolution that led to surviving groups, while discovering previously
unknown groups and the ancestral lines that linked them together.
For a while the largest gap of all remained, the ancestor of all the ants. There is no such thing as a
living solitary ant. All living species, so far as we know, form colonies with a queen and her sterile
(or almost sterile) daughters, who do all the work. Males are raised in the nest solely for the purpose
of mating with virgin queens. They leave the nest to find mates, are not allowed to return, and soon
die. King Solomon, who instructed, Go to the ant, thou sluggard, consider her ways, and be wise,
was obviously not aware of all the facts of ant biology in his moral urging. Nonetheless, how did this
bizarre but extremely successful social system come into existence? When I was a young scientist we
had many fossils to study, some dating back to more than fifty million years before the present, but
every species represented had worker castes. Of the origin of their social organization we knew
nothing.
This grail we ant biologists sought was a link still missinga primitive ant with colonies like
those of the ancestral forms that lived more than fifty million years ago, and simple enough to provide
clues to the origin of social behavior. The leading candidate of which we had knowledge at this time
was the Australian dawn ant (Nothomyrmecia macrops). Unfortunately, like the living aneuretines of
Sri Lanka, the species was known from only two specimens. These had been collected in 1931 in one
of the most remote places in the world. The land was the relatively inaccessible sand-plain heath of
Western Australia. In the 1950s this vast area, stretching from the small coastal town of Esperance in
the west to the edge of the desertlike Nullarbor Plain in the east, and covering over ten thousand
square miles in area, was entirely devoid of people. Two decades before my own visit, a party of
adventurers had traveled on horseback through this heath from the transcontinental highway south to
an abandoned homestead on the coast called the Thomas River Farm, thence about a hundred miles
west to Esperance. The terrain they crossed is one of the biologically richest in the world. In the
seemingly barren scrubland lived large numbers of plant species found nowhere else on Earth. The
insects were mostly unknown to science.
With the group in 1931 was a young woman who had agreed to collect ants along the trail for John
S. Clark, an entomologist at the Museum Victoria in Melbourne and the sole expert on ants in
Australia at that time. The collector carried a jar of alcohol into which she dropped ants wherever
she found them. When Clark examined the specimens he was startled to find two belonging to a
previously unknown ant species, primitively wasplike in form. It appears to be closest in anatomy
among all known living ants to what may have been the ancestor of all ants. Unfortunately, the
collector kept no records during the trek of where particular ant species had been found. The
Australian dawn ant might have been picked up anywhere along a hundred-mile line.
By the time I arrived in 1955 to study Australian ants, I was obsessed with the idea of
rediscovering this enigmatic species. It was already a legend among naturalists. I wanted to know
whether it was fully social, with well-organized colonies of queens and workers, or less soperhaps
just partway to the advanced condition of all other known ants. Biologists of the time otherwise had
no idea of how advanced ant social life had originated, or why.
Still young at twenty-five and charged with energy and optimism, I invited two fellow enthusiasts
to join me in the effort to rediscover Nothomyrmecia macrops. One was Vincent Serventy, a famous
Australian naturalist and authority on the Western Australian environment. The other was Caryl
Haskins, a longtime ant expert and at that time the newly appointed president of the Carnegie Institute
of Washington. We rendezvoused in Esperance, loaded up on supplies, and headed east in an old
army flatbed truck along a dirt track to the Thomas River Farm. The flat plain, clothed in flowering
shrubs and herbaceous plants, was beautiful to behold and blessedly emptywe saw only one other
vehicle during the entire trip. From this base we searched outward in all directions, night and day, for
the better part of a week. Dingoes prowled around our camp at night, the summer sun dehydrated us,
and our footsteps turned huge meat ant nests into boiling masses of angry red-and-brown, viciously
biting defenders. Was I afraid? Never. I loved every minute of it.
We devoted one day of our search to a trip northward to Mount Ragged, a prominence on whose
barren sandstone slopes the dawn ants might have been collected. The only water source, for the 1931
party and ourselves, was a moist spot on the roof of a shaded ledge, from which enough water
dripped to fill one cup each hour. No dawn ants were located there either.
Our overall effort yielded many new species of ants, but not a single specimen of the dawn ant.
Because of my high expectations, the failure was one of the greatest disappointments of my scientific
life.
Our failed expedition was nevertheless widely publicized in the Australian press, and it stimulated
further searches in the sand-plain heath by entomologists. There was a widespread feeling among the
local scientific cognoscenti that if this special insect was to be rediscovered and studied, it should be
by Australians and not by Americans, of whom more than enough had already visited the continent.
One such attempt was led by my former student Robert W. Taylor, who had completed his Ph.D. at
Harvard and at the time was a curator of entomology at the national insect collections in Canberra, the
capital of Australia. Bob was desperate to make the discovery, to seize this grail for himself and for
the honor of Australian entomology. On the way west to dawn ant country, the group camped in a
forest of mallee, a kind of shrubby eucalyptus. The night was chilly, and there seemed to be no good
reason to search for any insects at all. But Taylor walked out anyway with flashlight in hand, just in
case something might be active. A few minutes later he came running back, shouting, I got the bloody
bastard! I got the bloody bastard! As his words hint, now famous among entomologists, the dawn ant
had indeed been foundand if not by an Australian, at least by a New Zealander.
It turned out that the dawn ant is a winter species. The workers wait in their nests and come out on
cool nights to forage for mostly insects, many of which are numbed and easy to catch. The species is
part of the ancient Gondwanan fauna, insects and other creatures of which a large part originated in
Mesozoic times during the early breakup of the Gondwanan supercontinent and the drift northward of
New Zealand, New Caledonia, and Australia. The relict elements, of which the dawn ant is part, are
species adapted to the south temperate zone, and sometimes to the cool-temperature regimes of
winter. I should have anticipated that possibility when searching in midsummer out of Esperance. But
I didnt.
With a population of dawn ants located, a flood of studies followed, during which virtually every
aspect of the biology and natural history of the species was explored. Dawn ants proved to be
elementary in most aspects of their social behavior, but they are not the fundamentally less social
creatures we had hoped to find. Like all other known ants, they form colonies with queens and
workers. They build nests, forage for food, and raise their sisters. All are cooperating subordinate
daughters of the mother queen.
To discover the origin of all the ants, even taking into account their diminutive stature, is as
important as finding the origin of dinosaurs, birds, and even our own distant ancestors among the
mammals. I realized that without a satisfactory living link, researchers needed to find the right fossils
from the right geological period to make further progress. Until 1966, however, the earliest known
fossils were between a relatively youthful fifty million and sixty million years old, by which time, in
the early to middle Eocene Period, the ants were already abundant and highly diversified. They were
also globally distributed. We had even found an extinct species of dawn ant similar to the living one
of Australia, preserved in the Baltic amber of Europe.
It was all very frustrating. Ants obviously had arisen during the Mesozoic Era, which ended sixty-
five million years ago. But for a long time we had not a single Mesozoic specimen. It seemed as
though a dark curtain had been lowered over the ancestors and earliest species of these world-
dominant insects. Then, in 1966, word came to Harvard that two specimens of what appeared to be
ants had been found in ninety-million-year-old amber from a geological deposit in, of all places, not
some exotic far-off fossil bed but smack on the shores of New Jersey, and they were on the way for
me to examine. At last the curtain might lift! I was so excited that when I fished the amber piece out of
the mailing package I fumbled and it dropped to the floor. It broke into two pieces that skittered away
from each other. I was aghast. What disaster had I wrought? However, to my great relief each piece
contained an entire separate ant, and neither of the fossils had been damaged. When I polished the
surface of the pieces into glassy smoothness, I found the external form of the specimens to be
preserved almost as though they had been set in resin only a few days earlier.
My collaborators and I named the Mesozoic ant Sphecomyrma freyi, the first generic name
meaning wasp ant, and the second in honor of the retired couple who had found the specimens. The
generic name was fully justified: the species had a head that was mostly wasplike, some parts of the
body were mostly antlike, and other parts of the body were intermediate in form between wasps and
ants. In short, the missing link had been discovered, another grail found.
The announcement of the discovery set off a flurry of new searches by entomologists for ants and
antlike wasps in amber and sedimentary rock deposits of late Mesozoic age. Within two decades
many more specimens turned up in deposits from New Jersey, Alberta, Burma, and Siberia. In
addition to more Sphecomyrma, new species at other levels of evolutionary development came to
light. The story of the early diversification of the ants began to unfold. We found that it reaches back
at least 110 million years and probably well beyond, to as far as 150 million years before the present.
Yet, sadly, we still had only fossils. No living evolutionary links had been found whose social
behavior could be studied in the field and laboratory. It appeared that direct knowledge of the early
stages of social behavior in the ants might have to be pieced together indirectly. The Australian dawn
ant and a small number of other comparably primitive lines among the living ants might prove the best
that would ever be found.
Then in 2009 came a complete surprise with at least the potential to change the big picture. A
young German entomologist, Christian Rabeling, was excavating soil and leaf litter in rain forest near
Manaus, in the central Amazon. Rabeling, with whom Ive since worked in the field, has the deserved
reputation of leaving, literally, no stone unturned. He also readily climbed trees, unaided by
equipment, to bring down ant colonies nesting in the canopy. One day, as he was picking up every
new kind of ant he could find, he spotted a single pale, odd-looking specimen crawling beneath the
fallen leaves. Picking it up, he realized that he could not place it to any known genus or species of
ants.
During a visit to Harvard he brought his discovery along with the rest of his collection to the Ant
Room. Here, in cramped quarters on the fourth floor of Harvards Museum of Comparative Zoology,
is kept the largest and most nearly complete classified collection of ants in the world. Built up by a
succession of entomologists over more than a century, it contains perhaps a million specimens (no
one has volunteered to make an exact count), belonging to as many as six thousand species. Ant
experts from around the world come to these quarters to identify specimens they have collected on
their own, and to conduct research on classification and evolution. Several were present when
Rabeling brought in his Amazonian oddity.
After much consternation, the group invited me in from my office across the hall. I remember the
moment vividly. Taking a look under the microscope, I said, Good God, this thing must be from
Mars! Which meant I didnt have a clue either. Later, when Rabeling described the species formally
in a technical journal, he gave his ant the name Martialis heureka, which means, roughly, the little
Martian that has been discovered. It was an ant, all right, and proved an earlier branch in the ant
family tree than even the Australian dawn ant. At this writing three years later, no further Martialis
ants have been found. The Amazon is a very big place to look, however, and I expect a colony will
eventually be located if the species is truly social, and perhaps by one or more of the growing group
of young ant experts in Brazil.
You may think of my story of ants as only a narrow slice of science, of interest chiefly to the
researchers focused on it. You would be quite right. But it is nonetheless at a different level from an
equally impassioned devotion to, say, fly fishing, Civil War battlegrounds, or Roman coins. The
findings of its lesser grails are a permanent addition to knowledge of the real world. They can be
linked to other bodies of knowledge, and often the resulting networks of understanding lead to major
advances in the overall epic of science.
The basic tree of life with gene exchanges during the earliest evolution, as envisioned by the microbiologist W. Ford Doolittle. Modified
from the original drawing in Phylogenetic classification and the universal tree, by W. Ford Doolittle, Science 284: 21242128 (1999).
Thirteen
A CELEBRATION OF AUDACITY
SIX YEARS BEFORE the discovery of the archetypical ant Martialis in the Amazon forest, a major
effort had begun by entomologists to work out the family tree, more technically called the branching
phylogeny, of all the living ants. Therein lies yet another chapter of my story especially relevant to
you. In 1997 I had finally retired from the Harvard faculty and stopped accepting new Ph.D. students.
Nevertheless, in 2003, the chairman of the Graduate Committee of the Department of Organismic and
Evolutionary Biology called one day and said to me, Ed, weve already accepted our quota of new
students for this year, but weve got one more, a young woman so unusual and promising that well
add her on if youll agree to be her de facto sponsor and supervisor. Shes a fanatic on ants, wants to
study them above all else. And she has tattoos of ants on her body to prove it.
Dedication like that I admire, and after looking at her record I saw that Harvard was ideal for her.
And she, it seemed, would be ideal for Harvard. I recommended that Corrie Saux (later Corrie Saux
Moreau) from New Orleans be forthrightly admitted. When she appeared I knew we had made the
right decision. She breezed through the first-year basic requirements. By the end of the year she
already had a clear idea of what she wished to do for her Ph.D. thesis. Three leading experts on ant
classification, each in different research institutions, had just received a multimillion-dollar federal
grant to construct a family tree of all the major groups of ants in the world, based on DNA sequencing
the ultimate technique for the job. It was an important but formidable undertaking that, if successful,
would undergird studies on the classification, ecology, and other biological investigations of all of
the worlds sixteen thousand known ant species. Also, understanding the ants, many of the specialists
realized, means learning a great deal more about Earths terrestrial ecosystems.
Saux suggested that she write the three lead researchers for permission to decode one of the
smaller taxonomic divisions of the ants (one out of the twenty-one in all). I said, yes, it would be an
achievement worth a degree if she could manage it, and a good way to meet other experts and work
with them.
Soon afterward, however, she came back to tell me that the project leaders had turned her down.
They were disinclined to add a new, untested graduate student to the team. From my own student
days, I had learned to have a tough skin, not to accept a no as a personal rejection. With that in mind, I
said, Okay, dont let that get you down. What the project leaders decided isnt a bad thing. Why
dont you pick something else that youd like to do?
A few days later she came back and said, Professor Wilson, Ive been thinking, and I believe I
could do the whole project myself. I said, The whole project? She responded with demure
sincerity, Yes, all twenty-one of the subfamilies, all the ants. I think I can do it.
Corrie then added that the world-class collection at Harvard was a great advantage. All she
needed, she said, was a postdoctoral assistant who had specialized in DNA sequencing. She knew
one who was willing to take the job. Might I supply the money for his salary? After a pause, I said
impulsively, more out of instinct than logical reflection, Well, okay.
There was no bravado in Corrie, no trace of overweening pride, no pretension. She was a quiet,
serene enthusiast. As it turned out, she was also an open, helpful friend to fellow students and others
around her. Shed come from New Orleans by way of San Francisco State University, and I took
pride in her as a fellow southerner. I wanted her to succeed, and while I did not join as a
collaborator, I found the funds to set up her laboratory. And why not? An effort like this celebrates
imagination, hope, and audacity. And there was a fallback position for Corrie: if she fell short of the
whole, she could use the part completed as a thesis. I even helped, a little, on the side. When I visited
the Florida Keys on another project during the months that followed, I collected live ants of the genus
Xenomyrmex for her, filling in a group difficult to obtain in the field. Along the way, she told me she
needed to consult with an expert on some complex methods in statistical inference. I funded that also.
At this point I was determined to see Corrie Saux to the end. I felt that she could actually
accomplish what she envisioned.
Her thesis was finished in 2007, read closely by her Ph.D. committee, and approved. On April 7,
2006, the core of her study was published as the cover article in Science, an achievement that would
be considered exceptional even for a senior researcher. I admit I was nevertheless a bit tense when
Corries thesis went to the Harvard committee for review.
Then I learned that the three-person team with the larger grant had also finished their work and
planned to publish the results later in the year, allowing history to record that the two studies had
been conducted independently and simultaneously. Of this I warmly approved, especially since each
of the three was a highly regarded scientist. But it also meant that Corrie Sauxs research was about
to be thoroughly tested. What if the two phylogenies didnt match? That was a scenario I didnt want
to think about.
To my great relief, however, the two phylogenies matched almost perfectly. There was a difference
in the placement of one of the twenty-one subfamilies, the leptanilline ants, an obscure and little-
known group. Even that variance in interpretation was later worked out through more data and
statistical analysis.
The story of Corrie Saux Moreaus ambitious undertaking is one I feel especially important to
bring to you. It suggests that courage in science born of self-confidence (without arrogance!), a
willingness to take a risk but with resilience, a lack of fear of authority, a set of mind that prepares
you to take a new direction if thwarted, are of great valuewin or lose. One of my favorite maxims
is from Floyd Patterson, the light heavyweight boxer who defeated heavier men to win and for a
while hold the heavyweight championship. You try the impossible to achieve the unusual.
Locations of the evolution of cichlid fish species in Africa. Modified from Ecological opportunity and sexual selection together predict
adaptive radiation, by Catherine E. Wagner, Luke J. Harmon, and Ole Seehausen, Nature 487: 366369 (2012).
doi:10.1038/nature11144.
Fourteen
KNOW YOUR SUBJECT, THOROUGHLY
TO MAKE DISCOVERIES in science, both small and important, you must be an expert on the topics
addressed. To be an expert innovator requires commitment. Commitment to a subject implies
sustained hard work.
If you look beneath the surface of important discoveries to obtain a glimpse of the scientists who
made them, you will soon see the truth of this generalization. Here, for example, is testimony from the
theoretical physicist Steven Weinberg, who with Sheldon Lee Glashow and Abdus Salam won the
1979 Nobel Prize in physics for contributions to the theory of the unified weak and electromagnetic
interaction between elementary particles, including, interalia, the prediction of the weak neutral
current:
I was born in New York City to Frederick and Eva Weinberg. My early inclination toward
science received encouragement from my father, and by the time I was 15 or 16 my interests had
focused on theoretical physics . . .
After receiving my Ph.D. in 1957, I worked at Columbia and then from 1959 to 1966 at
Berkeley. My research during this period was on a wide variety of topicshigh energy behavior
of Feynman graphs, second-class weak interaction currents, broken symmetries, scattering
theory, muon physics, etc.topics chosen in many cases because I was trying to teach myself
some area of physics. My active interest in astrophysics dates from 196162; I wrote some
papers on the cosmic population of neutrinos and then began to write a book, Gravitation and
Cosmology, which was eventually completed in 1971. Late in 1965 I began my work on current
algebra and the application to the strong interactions of the idea of spontaneous symmetry
breaking.
Obviously, Steven Weinberg did not just wake up one morning, reach for pencil and paper, and
sketch out his breakthrough insights.
Switching to a very different subject, X-ray crystallography, we have James D. Watsons
characterization of Max Perutz and Lawrence Bragg. It is in The Double Helix, arguably the best
memoir ever written by a scientist, a book I recommend to any young person who wants to experience
almost personally the thrill of scientific discovery. In it he describes what proved to be the essential
step for solving the structure of the all-important coding molecule:
Leading the unit to which Francis [Crick] belonged was Max Perutz, an Austrian-born chemist
who came to England in 1936. [Perutz] had been collecting X-ray diffraction data from
hemoglobin crystals for over ten years and was just beginning to get somewhere. Helping him
was Sir Lawrence Bragg, the director of the Cavendish. For almost forty years Bragg, a Nobel
Prize winner and one of the founders of crystallography, had been watching X-ray diffraction
methods solve structures of ever-increasing difficulty. The more complex the molecule, the
happier Bragg became when a new method allowed its elucidation. Thus in the immediate
postwar years he was especially keen about the possibility of solving the structures of proteins,
the most complicated of all molecules. Often, when administrative duties permitted, he visited
Perutz office to discuss recently accumulated X-ray data. Then he would return home to see if
he could interpret them.
During nearly two decades, from 1985 to 2003, I brought to reality a dream that others before me
considered inordinately difficult or even impossible. Fitted in between my classes at Harvard in the
years before I retired, as well as other research and writing projects, I undertook the classification
and natural history of the gigantic ant genus Pheidole. This is no ordinary group. It comprises by far
the largest number of species of any ant genus, and further, it is among the largest genera of animals
and plants of any kind. In many regions of the world, from desert to grassland to deep rain forest, it is
also frequently the most abundant of all ants. What distinguishes Pheidole is the possession of two
castes, slender minor workers and much larger big-headed soldiers. The possession of such variation
within colonies adds to the biological complexity of these remarkable insects.
So great was the species roster that the taxonomy of Pheidole when I started my revision was in a
shambles. Most of the species recognized by earlier classifiers were unrecognizable from the brief
descriptions given them. Worse, the collections of specimens accumulated over the previous century
were scattered among half a dozen museums in the United States, Europe, and Latin America. By the
time I picked up the task, Pheidole could no longer be ignored. Its many species are collectively
among the major players in the environment. Ecologists trying to understand symbioses, energy flows,
the turning of soil, and other basic phenomena were unable to name the species they were observing.
Except for collection sites in North America, they were usually forced to report their specimens as
belonging to Pheidole species 1, Pheidole species 2, Pheidole species 3, and so on to species 20
and beyond. This might work, at least roughly, for one researcher at one locality. But other biologists
at other localities had their own independent rosters. Their Pheidole species 1, species 2, species 3,
and so forth were by chance alone very likely different from the rosters of others, and the lists could
be collated only if the researchers undertook the tedious task of bringing the specimens together.
Better if from the start all writers used the same comprehensive list, comprising, for example,
Pheidole angulifera, Pheidole dossena, Pheidole scalaris, and so on, each species having been
defined earlier in a careful, formal manner and made universally convenient in the literature. When
the taxonomy has been straightened out, biologists wishing to study the genus could identify the
species to their single acceptable name. They could immediately collate their findings with those of
other researchers, and pull from the literature everything previously known about every species of
interest.
Taxonomy is often spoken of as an old-fashioned discipline. Some of my friends in molecular
biology used to call it stamp collecting. (Maybe some still do.) But it is emphatically not stamp
collecting. Taxonomy, or systematics, as it is often called to spiff up its image, is fundamental to
modern biology. In technology it is conducted with the aid of sophisticated field and laboratory
research, using DNA sequencing, statistical analyses, and advanced information technologies. To take
its place in basic biology, it is grounded in studies of phylogeny (the reconstruction of family trees)
and in analyses of the genetics and geographical research devoted to the multiplication of species.
The task of taxonomy drawing from these disciplines is made the more difficult, however, by the fact
that most species of animals and microorganisms, together with a substantial minority of plants, await
discovery.
Ant taxonomists called the genus Pheidole the Mount Everest of ant taxonomy, towering arrogantly
in front of us, seemingly too big to be mastered. There were many lesser but still important challenges
on which others could build a productive career. I could face failure, I thought, so I took the job of
ascending the ant Everest, at first in collaboration with my old mentor William L. Brown. When
Bills health began to decline soon afterward, I soldiered on the rest of the way, starting with the
Western Hemisphere, the biodiversity headquarters of the genus. I felt obligated to continue to the
end, in part because I was located at the Museum of Comparative Zoology, with easy access to the
largest collection and best library in the world suited to the task. But I also persisted partly for the
challenge and partly because I thought of it as my duty. In the end, when Pheidole in the New World:
A Dominant, Hyperdiverse Ant Genus was published in 2003, the book comprised 798 pages in
which 624 species were diagnosed, 334 of them new to science, with everything known of the
biology of every species cited, and all of the species illustrated, with a total of over 5,000 drawings I
had made myself. Even as copies of Pheidole in the New World were being printed, new species
continued to pour into the museum from collaborators in the field. It is likely that by the end of the
century the total number of species will exceed 1,000, perhaps even 1,500, species.
I planted our flag on the Pheidole summit, so to speak, but I am no Edmund Hillary or Tenzing
Norgay. I had another goal in mind while encompassing the classification of the monster genus. One
was to discover new phenomena in the course of giving thought to each species in turn. I was
following the second of two strategies I gave you in an earlier letter: for each kind of organism there
exists a problem for the solution of which the organism is ideally suited. One success in this
correlative effort was the discovery of the enemy specification phenomenon. The principle behind
its concept is simple. Every species of plant and animal is surrounded in its natural habitat by other
species of plants and animals. Most are neutral in their effect upon it. A few are friendly, and at the
extreme, there is the symbiotic level. In the latter case, two or more are dependent upon one another
for their very survival or at least reproductionfor example, pollinator animals and the plants they
pollinate. A few other plant and animal species are, on the other hand, inimical to a particular
species, so much so in a few cases as to be dangerous to their survival. It is to the great advantage of
individuals of that species to recognize dangerous enemies instinctively and to avoid or destroy them
if possible.
The principle sounds like common sense. But do species really evolve such an enemy specification
response? I had never thought of it much one way or the other. Instead, I discovered it by accident.
During the Pheidole project I cultured laboratory colonies of Pheidole dentata, an abundant species
through the southern United States. I also kept colonies of fire ants (Solenopsis invicta). One day I
was conducting one of my easy, quick experiments by placing other kinds of ants and insects next to
the artificial nest entrances of the Pheidole dentata colonies just to see how they would respond. I
was especially curious to see which ones would draw out the powerful big-headed soldiers.
The response was usually tepid. Either the ants contacting the intruder retreated into the nest or,
with a few other nestmates, engaged it in combat. But when I dropped just a single fire ant worker at
the same spot, the reaction of the colony was explosive. The first forager to encounter the intruder
rushed back into the nest, laying an odor trail as it ran, while frantically contacting one nestmate after
the other. Both minor workers and soldiers then poured out of the nest, zigzagging and circling in a
search for the fire ant worker. When they found it they attacked it viciously. The minor workers bit
and pulled its legs, while the soldiers, employing their sharp mandibles and powerful adductor
muscles that fill their swollen heads, simply chopped off the appendages of the fire ant to render it
helpless.
The fire ants are certainly enemies of the deadly kind. When, in the laboratory, I placed Pheidole
and fire ant colonies close together, some of the fire ant scouts made it back home alive to report their
find and recruit nestmates to the battle. The far larger fire ant colonies quickly destroyed and ate their
opponents. Yet in some natural habitats, colonies of both species are abundant. It became apparent
that Pheidole survive by building their nests a safe distance from the fire ant colonies and killing off
fire ant scouts before they can report home.
Later, in the Costa Rican rain forest, I found an even more remarkable response by another species
(Pheidole cephalica) to rain or rising water that threatens to flood their nests. When I placed as little
as a drop or two at the entrance of a nest, minor workers quickly mobilized the colony, and the whole
emigrated within minutes to another location.
Discoveries like these, whether minor or importantand who is to say at first which it will be?
can be made only rarely without a thorough advance knowledge of the organisms studied. This
precondition is sometimes called a feel for the organism.
Let me relate another story to reinforce this important principle. It occurred during an expedition I
led in 2011 to the South Pacific. With me were Christian Rabeling, the ant expert and discoverer of
the Amazonian Martian ant; Lloyd Davis, another ant expert and world-class birder; and Kathleen
Horton, who was in charge of the complex logistics. We traveled during the austral spring of
November and early December. Our destination was two archipelagoes, the independent island
nation of Vanuatu and the nearby French possession of New Caledonia. In the process we visited
localities where I had collected and studied ants in 1954 and 1955. I looked forward to observing
changes in the environment that undoubtedly had occurred fifty-seven years later. I brought scanned
images of my aging Kodachrome slides with me to make the comparisons exact. In particular I wanted
to evaluate the condition of the wildlands and the reserves and national parks since 1955.
What original discoveries we made, in particular with the ants we planned to collect and study,
would depend entirely on the knowledge we brought with us. We were in fact well prepared. We
discovered many new species, and kept notes on the habitats in which they were found. But that was
only part of the plan. We had bigger game in mind: to clarify, if we could, phenomena in the formation
of species and their spread from one island group to another across the intervening ocean gaps. If you
look at a map of the South Pacific and make Vanuatu your focus, you see how plants and animals that
colonized this archipelago could have come from any of three bodies of land: Australia and New
Caledonia to the west, the Solomon Islands to the north, Fiji to the east, or some combination of all
three. Ant colonists, although completely landbound, might have made the journey by floating on the
logs and branches of fallen trees or blown by storm winds. Queen ants capable of founding colonies
might even have ridden in the feathers of far-ranging birds. We could not hope to determine how ants
cross open water, but we did collect enough data to judge which island group contributed the most
colonies to Vanuatu. It turned out, incidentally, to be the Solomon Islands.
This discovery was important enough to justify the hard work in the field, but we devised another
question to ask and perhaps answer. Leaving aside the Solomon Islands, whose ant fauna was still
poorly explored, we were aware of a huge difference between Vanuatu and the two archipelagoes on
either side of it, Fiji and New Caledonia. Both are ancient, having existed with a substantial land area
for tens of millions of years. Vanuatu has been in existence for a comparable period of time, but only
as a set of small, shifting islands. Only during the last million years has its land area been more than a
tenth of what it is today. The antiquity of Fiji and New Caledonia is immediately apparent in the
richness of their faunas and floras. In particular, each is occupied by a large number of species, some
highly evolved, that occur nowhere else in the world.
And what of relatively youthful Vanuatu? In November 2011 we were the first to take a close look
at the ants on this archipelago. We knew that if it had a long geological history and large land area
like New Caledonia and Fiji, we should expect to find a rich, highly evolved array of ants present. If,
on the other hand, the current large area of Vanuatu had a relatively short history, as the geologists
claimed, we should find a much sparser, distinctive array of ants there than occur on Fiji and New
Caledonia. As it turned out, we found a smaller array, in accord with expectations from the record
deduced by the geologists. But the ants of Vanuatu have not been inactive during their brief million-
year tenure. We found clear evidence of new species in formation, and the beginning of the kind of
expansion of biological diversity that is well advanced on the older archipelagoes. The ants of
Vanuatu, to put the matter as succinctly as possible, are in the springtime of their evolution.
I have one more story to tell you from the South Pacific, because it is about a process unfolding
there that may at first appear to be remote and exotic yet has global significance. It makes urgent the
lesson of knowing where you are and what to look for when doing field research.
While on New Caledonia, our little team joined Herv Jourdan, a seasoned resident entomologist
of the local Institute of Research and Development. He led us on a trip to the Isle of Pines, a small
island off the southern tip of the main island, Grand Terre, and, at least from the viewpoint of
Americans, one of the remotest places in the world. Our goal was to learn what kinds of ants occur
there, and to search for one species in particular, the bull ant Myrmecia apicalis. Bull ants are
evolutionary cousins of the Australian dawn ant, and almost as primitive as that species in anatomy
and behavior. Eighty-nine species of Myrmecia have been discovered in modern-day Australia. Only
one, Myrmecia apicalis, is native elsewhere. The existence of this insect so far from the homeland
raised questions of interest to biogeographers, whose business is to map and explain the distribution
of plants and animals. When and how did the New Caledonian bull ant get to this remote archipelago?
Which of the eighty-nine species back home in Australia are its closest relations? How has it adapted
to the island environment? In which ways, if any, has it become special?
I wanted very much to answer these questions when I visited New Caledonia in 1955, but I could
not find the species at all. The forest where it had been last seen on Grande Terre, the main island of
the New Caledonian archipelago, had been cut over in 1940. In later years Myrmecia apicalis was
considered extinct. But then Herv Jourdan found several workers of the ant in a forested area on the
Isle of Pines. We went there with him to locate colonies if possible and to learn all we could about
this endangered species. To our relief we succeeded in finding three nests deep in undisturbed forest,
and were able to film and study the ants day and night. The nests were located at the bases of small
trees. Their hidden tunnels were capped with debris. Foraging workers, we found, leave the nest at
dawn, climb singly into the canopy, return bearing caterpillars and other insect prey at dusk. Later we
learned that Myrmecia apicalis is most closely related to a few Australian bull ant species with
similar habits that live in the tropical forests of northeastern Australia. We still do not know how one
such species was able to colonize New Caledonia, or how many thousands or millions of years ago it
made the trip.
Im telling you this faraway bit of natural history for a special reason. While on the Isle of Pines
we confirmed the existence of a frightening threat to a large part of the islands biodiversity, not just
the New Caledonian bull ant, but a large part of the fauna. Another ant, accidentally introduced to
New Caledonia in cargo in recent years, has reached the small offshore island of Isle of Pines and is
taking over the forests there, destroying, as it spreads, the native ants, other insects, and in fact almost
all of the ground-dwelling invertebrates.
The alien enemy is the little fire ant (technical name: Wasmannia auropunctata), which
originated in the forests of South America. With humanitys unintended help, the species is spreading
throughout tropical regions of the world. I had first encountered this alien in the 1950s and 1960s in
Puerto Rico and the Florida Keys. Since then it has reached and begun to expand in New Caledonia,
where it is an especially destructive pest. Although its workers are tiny, the colonies are huge and
aggressive. The species is as bad as the more famous imported fire ant (Solenopsis invicta), which
has spread widely in warm temperate countries. The government of neighboring Vanuatu, aware of
the dangers posed by the Wasmannia, is attempting to keep it at bay by spraying and exterminating
beachhead populations whenever they are found on the islands.
The little fire ant is a particularly severe menace on the Isle of Pines. During our search for the bull
ants and other entomological treasures, we visited several types of forests, including those composed
of nearly pure stands of Araucaria, one of the signature plants of the New Caledonian archipelago.
These towering steeple-shaped trees have prevailed on the fringes of the southern continents for tens
of millions of years. We found that where the little fire ants had penetrated Araucaria groves, native
ants and other invertebrates were almost entirely absent. The New Caledonian bull ants survived in a
Wasmannia-free area, but that was only a mile or two from the slowly advancing fire ant wave. The
final extinction of these unique insects, and very likely other native animals, might be only decades
away.
Can the little fire ants be stopped? The French scientists at the Institute of Research for
Development in Noumea have tried to find a way, but so far have met only failure. You may be
thinking at this point that if Grande Terre and the Isle of Pines are so far away, why should we be
concerned? I will answer with emphasis: because the little fire ants are only one of thousands of
similar aliens spreading around the world. The number of invasive species of plants and animals,
including disease-carrying mosquitoes and flies, home-destroying termites, pasture-choking weeds,
and enemies of native faunas and floras, is increasing exponentially in every country. Invasive
species are the second most important cause of extinctions of native species, exceeded only by the
destruction of habitats through human activity.
To learn more of the details of the great invasive threat, and to find solutions before it has reached
catastrophic levels, will require far more science and science-based technology than we now
possess. Humanity needs more experts who have the passion and breadth of knowledge to know what
to look for in the first place. Thats where you come in, and why I have told you this story of New
Caledonias threatened bull ant.
IV
THEORY
and THE BIG PICTURE
A female of the fairyfly Mymar taprobanicum, a wasp parasite of insect eggs. The actual size is smaller than the first letter in this
caption. Klaus Bolte.
Fifteen
SCIENCE AS UNIVERSAL KNOWLEDGE
THERE IS ONLY one way to understand the universe and all within it, however imperfectly, and that is
through science. You are likely to respond, Not true, there are also the social sciences and
humanities. I know that, of course, Ive heard it a hundred times, and Ive always listened carefully.
But how different at their foundations are the natural sciences, social sciences, and humanities? The
social sciences are converging generation by generation of scholars with biology, by sharing methods
and ideas, and thereby conceding more and more to the realities of the ultimately biological nature of
our species. Granted that many in the humanities, as if in a bunker, fiercely defend their isolation.
Moral reasoning, aesthetics, and especially the creative arts are forged independently from the
scientific world view. The stories of human relationships in history and the creative arts are
potentially infinite, like music played upon only a few musical instruments. Yet however much the
humanities enrich our lives, however definitively they defend what it means to be human, they also
limit thought to that which is human, and in this one important sense they are trapped within a box.
Why else is it so difficult even to imagine the possible nature and content of extraterrestrial
intelligence?
Speculations about other kinds of mind are not pure fantasy. Rather, if informed they are thought
experiments. Lets try one. Imagine with me that termites had evolved a large enough size to have
brains with a capacity equal to that of humans. That may sound entirely implausible to you. Insects
have exoskeletons that encase their bodies like a knights armor. They cannot grow to be much larger
than a mouseand a human brain by itself is bigger than a mouse. But wait! Allow me a bit of
flexibility in the scenario. In the Carboniferous Period on this planet, 360 to 300 million years ago,
there were dragonflies cruising the air with three-foot wingspans, and four-foot-long millipedes
pushing their way through the undergrowth of the coal forests. Many paleontologists believe that these
monsters could exist because the atmosphere was much richer in oxygen than nowadays. That alone
would allow better respiration and larger size in the chitin-encased invertebrates. Furthermore, it is
easy to underestimate the capability of the insect brain. My favorite example is provided by the
female of a fairyfly, one in a taxonomic group of extremely small parasitic wasps, which hatches from
the egg of an underwater insect in which she has lived and grown up. She uses her legs as paddles to
swim up to the surface. She digs through the tension of the surface film, and walks on top of it for a
while. Then she flies in search of a mate, copulates, returns to the water, digs through the surface
tension again, paddles to the bottom, searches until she finds an egg of the appropriate host insect, and
lays one of her own inside it. The female fairyfly does all this with a brain almost invisible to the
naked eye.
Equally impressive, honeybees and some species of ants can remember the location of up to five
places where food is found and the time of day at each when food is available. Workers of an African
hunting ant prowl singly over the forest far from their colonys nest. They circle and zigzag during the
excursion. As they travel, they memorize the pattern of the foliage seen above their heads against the
sky. Occasionally, they stop and look up to summarize where they are: upon catching an insect, they
use this mental map to run home in a straight line.
How can an insect process so much information with a brain not much larger than the period below
the question mark at the end of this sentence? The principal reason is the way the insect brainmuch
more efficient by unit volumeis constructed. Glial cells, which support and protect the brain cells
of larger animals, including us, are omitted in the insects, allowing more brain cells to be packed into
the same space. Also, each insect brain cell has many more connections on average to other cells than
do those of vertebrates, allowing added communication by means of fewer information distribution
centers.
So if I have rendered to your satisfaction at least plausibly the existence in a past era of high insect
intelligence, let me go on to outline the morality and aesthetics of an imaginary termite-like
civilization on another planet similar to our own, which Ive based on Earth termites of the present
day but bigger and raised to human-level intelligence. Its science fiction, of course, but unlike most
such fiction, it is fully based on solid science.
SUPERTERMITE CIVILIZATION ON A DISTANT PLANET
Imagine, if you will, a vampire-like species that shuns the light of day, dying quickly if
exposed to it. These termites come out to forage for food only if they must, and then only at
night. They treasure complete darkness, high humidity, and constant heat. They eat rotting
vegetable material. Some also consume fungi they grow in gardens mulched by rotting
vegetation. As with some social insect species on Earth, only the king and queen are allowed
to reproduce. The queen, her abdomen hugely swollen with ovaries, lies within the royal cell,
doing almost nothing else but eat. She lays a constant stream of eggs, and occasionally mates
with the little king who stands at her side. The hundreds or thousands of workers in the
queendom, freed like human priests and nuns from sexual turmoil, devote their lives selflessly
to rearing their brothers and sisters. A rare few of the young turn into virgin kings and
queens, who leave the colony, find mates of their own, and start new colonies. The workers
further attend to all of the other tasks, including education, science, and culture, of this
supertermite civilization. Many of the inhabitants are soldiers, fitted with massive muscles
and jaws and glands from which they spit poisonous saliva, ever ready for the chronic battles
that break out among the colonies.
Life is spartan, and any deviation from the rules of the group, any attempt to reproduce or
to attack others, is punished by death. Corpses of the workers that have died for any reason
are eaten. Workers who grow ill or suffer injuries are also eaten. Communication is almost
wholly by pheromones, from the tastes and scents of secretions released from glands located
up and down the length of the body, as the source of our sound is in our larynx and mouth.
Think of our human way in this remarkable line from Vladimir Nabakovs famous novel
Lolita: Lo-lee-ta: the tip of the tongue taking a trip of three steps to tap, at three, on the
teeth. Imagine then the release of pheromones from the line of pheromones in different
combinations, different sequences, perhaps a trip of three stages in puffs of pheromone from
the openings of glands along the side of the body. Pheromonal music, translated into sounds,
might sound beautiful to us. It could unfold in melodies, cadenzas, beats, crescendos, and,
with orchestras of the supertermites participating, symphonies, much more. All this would be
experienced by smell.
The supertermite culture would thus be radically different from ours, and extremely difficult to
translate. The species would have its termitities as our species has its humanities. Yettheir science
would be closely similar; its principles and mathematics could be mapped unambiguously onto our
own. Supertermite technology might be more or less advanced, but it too would have evolved in
parallel manner.
We would not like these supertermites, nor, I suspect, any other intelligent alien we encountered.
And they would not like us. Each would find the other not just radically different in sense and brain,
but morally repugnant. But this said, we could share our scientific knowledge to great mutual
advantage. And, oh, before I forget to remind you. You dont need to engage in fantasy to envision
cultures, or whole faunas and floras, on another planet. In fact, my extraterrestrial termites, minus
culture, are based on the real mound-building termites of Africa.
Similar wonders await your attention. The universal nature of scientific knowledge yet to be
revealed includes a near-infinitude of surprises.
New kinds of mussels and other novel organisms discovered in deep-sea hydrothermal vents on the Mid-Atlantic Ridge. Modified from
original painting. Abigail Lingford.
Sixteen
SEARCHING FOR NEW WORLDS ON EARTH
TO MAKE IMPORTANT DISCOVERIES anywhere in science, it is necessary not only to acquire a broad
knowledge of the subject that interests you, but also the ability to spot blank spaces in that knowledge.
Deep ignorance, when properly handled, is also superb opportunity. The right question is
intellectually superior to finding the right answer. When conducting research, it is not uncommon to
stumble upon an unexpected phenomenon, which then becomes the answer to a previously unasked
question. To search for unasked questions, plus questions to put to already acquired but unsought
answers, it is vital to give full play to the imagination. That is the way to create truly original science.
Therefore, look especially for oddities, small deviations, and phenomena that seem trivial at first but
on closer examination might prove important. Build scenarios in your head when scanning
information available to you. Make use of puzzlement.
While Ive spent a lot of time thus far on biology, obviously because I am a biologist, I am happy to
emphasize that other fields of science yield comparable treasures of discovery. Ive worked enough
with mathematicians and chemists in particular to know that their heuristicstheir process of making
discoveriesis closely similar. Organic chemistry, for example, to substantial degree consists of
exploring the almost endless array of possible molecules, and the occurrence of this chemodiversity
in the natural world, and finally the physical and combinatorial properties of each kind of molecule.
Take the elementary hydrocarbon CH and run it in series up through C, C, C, and beyond, adding
double and triple bonds, and sprinkle along the way the radicals S (sulfur), N (nitrogen), O (oxygen),
and OH (hydroxy-), varying the form when possible into pure and branching strings, cycles, helices,
and folds. The number of potential molecular species rises with molecular weight at a rate faster
than exponential. Four million organic compounds were known by 2012, with 100,000 more being
characterized each year, comparing favorably with 1.9 million biological species known and 18,000
new species added each year. Most of organic chemistry, and within it natural-products chemistry,
consists of the study of the synthesis and characteristics of the molecules. Special attention is paid to
those occurring in living organisms, where organic chemistry turns into biochemistry. Virtually all of
lifes processes and all of living structures are but the interplay of organic molecules. A cell is like a
miniature rain forest, into which biochemists and molecular biologists conduct expeditions to find and
describe organic structure, variety, and function.
The mind-set of astronomers is similar. They wander through the near-infinitude of space and time
to find and describe the arrays of galaxies and star systems, and the forms of energy of matter within
and between them. The development of particle physics has likewise been a journey into the
unknown, to explore the ultimate components of matter and energy.
Across thirty-five powers of magnitude (powers of ten, hence of magnitude 1, 10, 100, 1000, and
so on), from one subatomic particle to the entirety of the universe, science rules the enterprise of the
human imagination applied to the laws of reality. Even if our intellect were somehow limited to the
biosphere alone, scientific research would still be an endless adventure of exploration. Life invests
the planet surface totally; no square meter is entirely free of it. Bacteria and microscopic fungi exist
on the summit of Mount Everest. Insects and spiders are blown there by thermal drafts; and a few,
including springtails and the jumping spiders preying on them, survive on the slopes close to the very
top. At the extreme opposite in elevation, the bottom of the Mariana Trench in the western Pacific,
thirty-six thousand feet below the ocean surface, bacteria and microscopic fungi flourish, and, with
them, fish and a surprisingly large variety of single-celled foraminiferans.
There must be by definition somewhere on Earth a site with the greatest variety of organisms. The
Yasuni National Park of Ecuador, which encloses a magnificent rain forest between the Rio Napo and
Rio Curaray, is reputed to be that one biologically richest place on Earth. More precisely, its 9,820
square kilometers are believed to contain more species of plants and animals than any other piece of
land of comparable area. The known roster supports the claim: recorded in the whole park are 596
bird species, 150 amphibian species (more than the number in all of North America), as many as
100,000 insects, and, growing in just a single average upland hectare, 655 tree speciesalso more
than occur in all of North America. The only question about Yasunis supremacy is whether there
might exist some other, less explored section of the Amazon and Orinoco Basins that will prove even
more diverse. At the very least, the Yasuni National Park is very close to the extreme of its kind. And
outside the Amazon-Orinoco region, nothing in the world can approach it.
There is another reason to pay attention, not yet widely recognized even by most biologists: the
Yasuni National Park may harbor the highest species numbers that have ever existed. Throughout the
entire history of life, from the Paleozoic Era forward, 544 million years, the number of plant and
animal species worldwide has been very slowly rising. Thus at the breakout from Africa and
worldwide spread of Homo sapiens, beginning about 60,000 years before the present, Earths
biodiversity was likely at its all-time maximum. Then, extinction by extinction, human activity began
to whittle the number down, and today that pace is accelerating. For the time being, Yasuni holds its
own, and that is why it is recognized as a world treasure. We know only a fraction of the species of
animals, especially the insects, found in the Yasuni, and next to nothing of their biology. We would
like to take the full measure of this place, and of others of similar extreme high diversity, and come to
understand the reason for its preeminencebefore it is ruined by human greed.
In extreme opposition, there exists on Earth a close outward approximation of the lifeless surface
of Mars. In its own way it has been worth exploring. The place is the McMurdo Dry Valleys of
Antarctica. To casual inspection the land seems as sterile as the surface of autoclaved glassware. But
life is there, and it makes up the sparest and most stubborn of all of Earths ecosystems outside the
open surface of polar ice. Even though nitrogen is at the lowest concentration of any habitat on Earth,
and water is almost nonexistent, it is surprising to find bacteria in the soil of the McMurdo Dry
Valleys. The rocks scattered about seem lifeless, yet some are etched with almost invisible crevices
in which communities of lichens live. These organisms are minute fungi that live symbiotically with
green algae. They are concentrated layers just two millimeters beneath the surface of the rocks.
Farther in, other such endoliths (living in rocks) include bacteria capable of their own
photosynthesis.
Scattered about in the McMurdo Dry Valleys are frozen streams and lakes, which contribute a
small amount of moisture in the surrounding soil. The free water, which occurs in droplets and films,
harbors small numbers of almost microscopic animals: tardigrades, the strange creatures sometimes
called bear animalcules that I mentioned earlier, rotifers (wheel animalcules), and, most
abundant of all, nematodes, also called roundworms. Although barely visible to the naked eye, the
nematodes are the tigers of the land, the top of the food chain in this quasi-Martian world, and the
antelope equivalents on which they feed are bacteria in the soil. In a few places can also be found
rare mites and springtails, the latter a primitive form of insect. In all, sixty-seven species of insects
have been recorded from the combined habitats of Antarctica, but only a few are free-living. The
great majority are parasites that live in and on the warm plumage of birds and the fur of mammals.
As I write, there are many other places on the planet in which biological exploration has only
begun. The greatest depths of the ocean, the abyss of eternal dark, consists of great submerged
mountain ranges incised by deep unvisited valleys and intervening vast plains. The tips of many of the
mountains rise above the water to form the oceanic islands and archipelagoes. Some come close but
remain submerged. There are the seamounts. Their peaks are coated with marine organisms, many of
whose species are unique to the location. The exact number of seamounts is still unknown. It has been
estimated to run in the hundreds of thousands. Imagine the extent of human ignorance! Beneath the
surface of the oceans and seas, which cover 70 percent of the Earths surface, there exists an all but
countless number of lost worlds. Their complete exploration will occupy generations of explorers
from every discipline of science.
Life on Earth remains so little known that you can be a scientific explorer without leaving home.
We have scarcely begun to map Earths biodiversity at any level, from molecule to organism to niche
in an ecosystem. Consider the following numbers of known and unknown species among different
taxonomic groups of organisms around the world. They are why I like to call Earth a little-known
planet. The data were pulled from global surveys made under the auspices of the Australian
government in 2009.
The total number of species estimated in 2009 to have been discovered, described, and given a
formal Latinized names worldwide was 1.9 million. The true number, both discovered and remaining
to be discovered, could easily exceed 10 million. If the single-celled bacteria and archaea, the least
known of all organisms, are added, the number might soar past 100 million. Five thousand kilograms
of fertile soil contain, by one estimate, 3 million species, almost all unknown to science.
Why havent scientists made more progress in exploring the world of bacteria and archaea? (The
latter are an important group of single-celled organisms that outwardly resemble bacteria but possess
very different DNA.) One reason for our ignorance is that a satisfactory definition of species in
these organisms remains to be made. An even more important reason is that the different kinds of
bacteria and archaea are so diverse in the environments they require in order to grow, and in the food
they need to eat. Microbiologists have not learned how to culture the great majority of bacteria and
archaea, in order to produce enough cells for scientific study. With the advent of rapid DNA
sequencing, however, the genetic code of a strain can be determined with only a few cells. As a
result, the exploration of species diversity has increased dramatically.
In citing these remarkable figures on biodiversity, I am not suggesting that you plan to become a
taxonomistalthough for now and many years ahead that would not be a bad choice. Rather, I wish to
stress how little we know of life on this planet. When we also consider that the species is only one
level in the hierarchy of biological organizations, molecule to ecosystem, then the immense potential
of biology, and of all of the physics and chemistry relevant to biology, becomes immediately
apparent.
If scientists know so little of raw biological diversity at the taxonomic level, we know even less of
the life cycles, physiology, and niches of each species in turn. And for all but a very few localities on
which biologists of diverse training have focused their energies, we are equally ignorant of how the
idiosyncratic traits of individual species fit together to create ecosystems. Ponder these questions for
a while: How do pond, mountaintop, desert, and rain forest ecosystems really work? What holds them
together? Under what pressures do they sometimes disintegrate, and how and why? In fact, many are
crumbling. Humanitys long-term survival depends on acquiring answers to these and many other
related questions about our home planet. Time is growing short. We need a larger scientific effort,
and many more scientists in all disciplines. Now Ill repeat what Ive said when I began these letters:
you are needed.
The female gypsy moth, located at the lower point of the active space, releases a pheromone cloud within which is a region of high
concentration followed by the male. Drawing by Tom Prentiss (moths) and Dan Todd (active space of gyplure Scientific American).
Modified from Pheromones, by Edward O. Wilson, Scientific American 208(5): 100114 (May 1968).
Seventeen
THE MAKING OF THEORIES
THE BEST WAY I can explain the nature of scientific theories to you is not by abstract generalizations
but by offering examples of the actual process of making theory. And because this part of science is
the product of creative and idiosyncratic mental operations that are seldom put into words, I will stay
as close to home as possible by using two such episodes in which I have been personally involved.
The first is the theory of chemical communication. The vast majority of plants, animals, and
microorganisms communicate by chemicals, called pheromones, which are smelled or tasted. Among
the few organisms that use sight and sound primarily are humans, birds, butterflies, and reef-dwelling
fish. Working with the social behavior of ants in the 1950s, I became aware that these highly social
insects use a variety of substances that are released from different parts of the body. The information
they transmit is among the most complex and precise found in the animal kingdom.
As new information began to pour in, those of us conducting the early research saw that we needed
a way to pull together the fragmented data and make sense of them. In short, we needed a general
theory of chemical communication.
I was extremely fortunate during this early period to serve as the cosponsor of William H. Bossert,
a brilliant mathematician working for a Ph.D. in theoretical biology. After completing his degree
requirements in 1963, he was invited to join the Harvard faculty, and in a short time thereafter he
received a tenured professorship in applied mathematics. While still a graduate student, he joined me
in creating a theory of pheromone communication. The time was right for such an effort, and we were
successful. On no other occasion in my scientific career has a project worked out as quickly and as
well as did the collaboration with Bill Bossert.
To kick things off, I told him what I knew about the new subject. I laid out the basic properties of
chemical communication as I had come to understand them. There was not a great deal of information
to go on in this early period. From field and laboratory studies, I said, we knew that a wide variety of
pheromones exist. It seemed logical that we should begin with a classification of the roles of all of
those known, then try to make sense of each one in turn. The theory should deal not just with form and
function of the pheromone molecules, which was the goal of most researchers, but also with their
evolution. Put simply, we wanted to know what the pheromones are and how they work, of course,
but also why they are one kind of molecule and not another.
Before giving you the theory, here are the specific why questions we meant for it to explain. Is
the pheromone molecule used the best way possible, or is it one that was selected at random during
evolution out of a limited array available for the job? What do the pheromone messages look like if
you could see them spreading through space? Should the animal emit a lot of the pheromone or just a
little in each message? How far and fast do the pheromone molecules travel through air or water, and
why?
Here, then, in a nutshell, is the theory. Each kind of pheromone message has been engineered by
natural selectionthat is, trial and error of mutations that occur over many generations resulting
in the predominance of the best molecules, with the most efficient form of transmission allowed by
the environment. Suppose a population of ants is started by two ant colonies who compete with each
other. The first colony makes one kind of molecule and dispenses it in a certain way, and the second
colony makes another kind of molecule that is less efficient, or else is dispensed less efficiently, or
both. The first colony will do better than the second, and as a consequence it will produce more
daughter colonies. In the population of colonies as a whole, the descendants of the first colony will
come to predominate. Evolution has occurred in the pheromone, or in the way it is used, or both.
Bossert and I agreed: Lets think about ants and other organisms using pheromones as engineers.
This thought took us quickly to ants recruiting other ants by laying a trail for them to follow. So, at the
next picnic (or on your kitchen floor if the house is infested) drop a crumb of cake. It is logical to
suppose that the ant scout that finds it needs to dribble out the trail pheromone at a slow rate in order
to make the store of the substance she carries in her body last a long time. The piece of cake may be
several ant-mile equivalents away. In this function, the ant is like an automobile engine designed for
high mileage. In order to achieve such efficiency, the pheromone needs (in theory) to be a powerful
odor for the ants following the trail. Only a few molecules should suffice. Also, the pheromone must
be specific to the species using it, in order to provide privacy. It is bad for the colony if other ants
from other species can pirate the trail, and even dangerous for the colony if a lizard or some other
predator can follow the trail back to the nest. Finally, the trail substance should evaporate slowly. It
needs to persist long enough for other members of the colony to track it to the end, and start laying
trails of their own.
Then there are the alarm substances. When a worker ant or other social insect is attacked by an
enemy, whether inside or outside the nest, it needs to be able to shout loud and clear, in order to get
a fast response. The pheromone must therefore spread rapidly and continuously over a long distance.
But it should also fade out quickly. Otherwise even small disturbances, if frequent, would result in
constant pandemoniumlike a fire alarm that cannot be turned off. At the same time, unlike the case
for trail substances, there is no need for privacy. An enemy can gain little by approaching a location
teeming with alert and aggressive worker ants.
Let me pause here to describe an easy way for you to smell an alarm pheromone yourself. Catch a
honeybee from a flower in a handkerchief or other soft cloth. Squeeze the crumpled cloth gently. The
bee will sting the cloth, and as it draws away it will leave the sting (which has reverse barbs) stuck
in the cloth. When that happens, the immobile sting pulls out part of the bees internal organs. Let the
bee move to the side, then crush the sting and the organs between two fingers. You will smell an odor
that resembles the essence of banana. Its source is a mixture of acetates and alcohols in a tiny gland
located along the shaft of the sting. These substances function as an alarm signal, and they are the
reason other bees rush to the same site and add their own stings. Next, if the eviscerated bee hasnt
flown away, crush its head and smell that. The acrid odor you detect is from a second alarm
substance, 2-heptanone, emitted by glands at the base of the mandibles. (Dont feel bad about killing a
worker bee. Each has an adult life span of only about a month, and it is only one of tens of thousands
that make up a colony. The colony in turn is potentially immortal, since new mother queens replace
the old ones at regular intervals.)
The next category of pheromones are the attractants, in particular the sex pheromones, by which
females call to males for the purpose of mating. The phenomenon is widespread not only in social
insects but also throughout the animal kingdom. Other attractants also include the scent of flowering
plants, in which the flowers call to butterflies, bees, and other pollinators. The most dramatic
substances of the kind are the sex attractants of female moths, which can draw males upwind for
distances of a kilometer or more.
Finally, Bossert and I reasoned in our initial classification, there are the identification substances.
An ant, upon smelling these substances, can tell whether another ant is from the same or a different
colony. It can also identify a soldier, ordinary worker queen, egg, pupa, or larva, and if the latter, its
age. Carrying a chemical badge of this kind with you at all times means wearing the pheromone like a
second skin. An identity pheromone is a single substance or, more likely, a mix of substances. It needs
to evaporate very slowly and be detectable only at a very close range. If you closely watch one ant or
some other social insect approach another, say while running along a trail or entering a nest, you will
see the two sweep each others body with their two antennaea movement almost too fast for the eye
to catch. They are checking body odor. If they detect the same odor, each will pass the other by. If the
body odor is different, they will either fight or else flee from each other.
Reaching this point in the investigation, Bossert and I left the adaptive engineering method of
evolutionary biology and passed into biophysics. We needed to envision the spread of the pheromone
molecules from the body of the animal releasing them, and as precisely as possible. Obviously, as the
pheromone cloud disperses, its density would declinethere would be fewer and fewer molecules in
each cubic millimeter of space. Eventually there would be too few to smell or taste. Bossert then
devised the crucial idea of active space, within which the molecules are dense enough to be
detected by the receiving plant, animal, or organism. He constructed models (at last, a place for pure
mathematics!) to predict the shape of the active space. We were now in a new phase in creating the
theory of pheromone communication.
With the ant or any other broadcasting organism sitting on the ground in still air, the shape of the
active space would be hemisphericalone half of a sphere cut in twowith the broadcaster at the
center of the flat surface. When an organism releases the pheromone from a leaf or object off the
ground and in an air current, the shape of the active space would be an ellipsoid (roughly, shaped like
an American football), tapering to a point at each end. The broadcaster would be at one of the points,
releasing the pheromone downwind. When a trail is laid on the ground in quantities sufficient for it to
be detected over a long period of time, the space would become a very long semiellipsoid, in other
words an ellipsoid cut in half lengthwise at ground level.
Next we turned our attention of the design to the molecule itself. Trail substances and identification
odors should consist, we reasoned, of either relatively large molecules or mixes of large molecules.
They should diffuse slowly. Alarm pheromone molecules should be chosen in evolution to be smaller
in size. They should form a more limited active space, and dissipate quickly. The qualities of the
active space depend on five variables that can be measured: the diffusion rate of the substance, the
surrounding air temperature, the velocity of the air current, the rate at which the pheromone is
released, and the degree of sensitivity of the organism receiving it. With these measurable quantities
in place, the theory began to take shape in a form that could be taken into the field and laboratory, and
used to study animals as they communicated.
Next, we left biophysics for a while and entered the realm of natural products chemistry to learn
the nature of the pheromone molecules. Its the same chemistry used widely in pharmaceutical and
industrial research. It was our good luck that a recent major advance in molecular analysis put this
part of the pheromone story within reach. By the late 1950s, the new technique of gas chromatography
coupled with mass spectrometry made it possible to identify substances in quantities as little as a
millionth of a gram, or less. Where previously chemists needed thousandths of a gram of pure
substance to get the job done, now they needed only thousandths of a thousandth. The technique has
allowed the detection of trace substances, including toxic pollutants, in the environment. Along with
DNA sequencing (also requiring only a droplet of blood or the wipe of a wineglass), it also soon
transformed forensic medicine. For us and other researchers it made possible the identification of
pheromones carried in the body of a single insect. Ants commonly weigh between one and ten
milligrams each. If a particular pheromone takes up only a thousandth or even a millionth of its body
weight, it is still possible for researchers to make some progress in the characterization of the
molecule. The chemists I worked with could obtain hundreds or thousands of ants. That was no great
featit takes only a shovel and a bucketand is one of the great advantages of working with ants. It
became possible not only to isolate candidate pheromones but also to obtain enough of the material
for bioassaystesting the material with live colonies to see if it evokes what theory suggests is the
correct response.
In an early stage of pheromone research a biochemist, my friend John Law, and I set out to identify
the trail substance used by the imported fire ant, which by that time had become one of the more
noxious insect pests of the American South. We thought that in order to have plenty of the pheromone
we should collect tens of thousands or even hundreds of thousands of the ants for extraction of the
critical substance. That seemed quite practicable, because each fire ant colony contains upward of
two hundred thousand workers. And I happened to know a way to gather that many fire ants quickly
and efficiently. The imported fire ant, as a native to the floodplains of South America, has a unique
way to avoid rising water. When the ants sense the approach of a flood from around and below them,
they move to the surface of the nest, carrying with them all the young of the colonythe eggs, the
grublike larvae, and the pupaewhile nudging the mother queen upward as well. When the water
reaches the nest chambers, the workers form a raft of their bodies. The whole colonial mass then
floats safely downstream. When the ants contact dry land, they dissolve their living ark and dig a new
nest.
It occurred to me that if we simply excavated fire ant nests and dumped them and the soil into
nearby pools of water, the colony would rise to the surface and gather as an ant-pure raft while the
dirt settled to the bottom. We tried this crude method on roadsides outside Jacksonville, Florida, and
it worked. We came back with the requisite one hundred thousand worker ants (roughly estimated, not
counted!) and my hands covered with itching welts from the stings of many angry ants.
Back at Harvard in Laws laboratory, the search for the fire ant trail pheromone at first went well.
The crucial substance appeared to be a relatively simple moleculea terpenoidand its complete
molecular structure seemed within reach. Then came frustration, and a mystery. As the chemists
attempted to purify the substance in order to characterize it definitively, and we proceeded to assay
the reactions they produced by laying artificial trails in the laboratory, the response to the fraction
supposedly containing the pheromone grew progressively weaker. Was the pheromone an unstable
compound? Thinking that to be a good possibility, and concluding that the substance probably
couldnt be identified with the equipment and material available, we quit. To help others making the
attempt we published a note in the science journal Natureone of the few articles the editors have
ever accepted that reported a failed experiment.
Years later, Robert K. Vander Meer, a natural product chemist working on fire ant pheromones in
Florida, discovered the reason for our failure. The trail substance, it turned out, is not a single
pheromone, but a medley of pheromones, all released from the sting onto the ground. One attracts
nestmates of the trail layer, another excites them into activity, and still another guides them through the
active space created by the evaporating chemical streaks. All of the components need to be present to
evoke the full response in a fire ant worker seen in the field and laboratory. By not realizing this
complexity, and thereby taking aim only at one of the components, we had failed to identify any of
them.
In the 1960s and 1970s research on pheromones deepened and expanded, becoming an important
part of the new discipline of chemical ecology. Researchers worked out with increasing accuracy
what proved to be the complex pheromone codes of ant and honeybee colonies. Our theory of
engineering by natural selection proved out well. However, recognizing that we had dealt with
biology, and the independent events of natural selection, the correlations we proposed were only
roughly met. A few strange, idiosyncratic exceptions were found, some of which to this day await
further theory and experimental testing.
Ecosystems, with their rich complexes of interacting plants, animals, fungi, and microorganisms,
came to be seen in a new way and the theories that guide ecology were altered accordingly. There
was a different sensory world to be understood, one wholly invisible to human sight and hearing. The
signals are in the air, spread over the ground, and beneath in the soil, and in pools of water. They
form a crisscrossing of odors and scents, a riot of voices unheard by us that variously broadcast,
threaten, or summon: Check me as I approach you, I am a member of your colony. I have discovered
an enemy scout, now hurry, follow me. I am a plant whose flowers have opened up this night and I
wait here for you, come to me for a meal of pollen and nectar. I am a female cecropia moth
calling, so if you are a male cecropia moth, follow my scent upwind, come to me. I am a male
jaguar, alone on my territory, if you have detected this scent, you are trespassing, so get out, get
out now.
By science and technology we have entered this world, but we have only begun to explore it. Only
when it becomes better known will we gain a part of the knowledge needed to understand how
ecosystems are put together and, from that, how to save them.
Now I hope you see how theories are made, and how they work. The process can be messy, but the
product can be true and beautiful. As factual information grows about any subjectin this case
chemical communicationwe dream about what it all means. We make propositions about how the
phenomena we discovered work and how they came into existence. We find a way to test these
various hypotheses. We look for a pattern that emerges when we put the parts together, like a jigsaw
puzzle. If we find such a pattern, it becomes the working theorywe use it to think up new kinds of
investigation, in order to move the whole subject forward. If this extension doesnt work very well
and now facts appear that contradict the theory, we adjust it. When things get bad enough, we junk the
theory and create a new one. With each such step, science moves closer to the truthsometimes
rapidly, sometimes slowly. But always closer.
Woolly mammoths, a now-extinct species of the World Continent Fauna. Modified from the original painting. Natural History Museum
Picture Library, London.
Eighteen
BIOLOGICAL THEORY ON A GRAND SCALE
MY SECOND EXAMPLE of the growth of theory is from biogeography, the science that explains the
distribution of plants and animals. In its global reach of space and time, biogeography is the ultimate
discipline of biologyin the same sense that astronomy is the ultimate discipline of the physical
sciences. When the mapping of species around the world is added to the study of how they got there,
biogeography acquires a noble grandeur. At least, that was how I felt when as a college student in my
late teens I looked up from my studies of descriptive natural history to study the processes of
evolution. I learned to ask: What kind of process creates biodiversity? What other kind scatters
species into their current geographic ranges? Neither kind occurs at random, I read. Both are the
products of understandable causes and effects. I was already totally devoted to making a career in
natural history, as an expert on insects. A government entomologist, perhaps, or a park ranger, or a
teacher. Now I rejoiced. I could also be a real scientist!
The first revelation for me came from the Modern Synthesis of evolutionary theory. Put together
mostly in the 1930s and 1940s, it united the original Darwinian theory of evolution by natural
selection with advances being made in the modern disciplines of genetics, taxonomy, cytology,
paleontology, and ecology. I was especially impressed by Ernst Mayrs 1942 synthesis, Systematics
and the Origin of Species, which I could immediately apply to my knowledge of taxonomy, the
systematic classification of organisms. Suppose you yourself were working on a particular subject,
say the colors of gems or the taste of wines, and you came upon a theoretical work that seemed to
make sense of everything you already knew. You would have the same kind of transformative
experience.
Later, as a graduate student at Harvard, I discovered a remarkable work on theory of biogeography
only occasionally noticed by previous scientists: William Diller Matthews Climate and Evolution,
published in a 1915 issue of Annals of the New York Academy of Sciences. In it the eminent
vertebrate paleontologist, who worked as a curator of mammals in the American Museum of Natural
History located in New York City, proposed a grand scheme for the origin and spread of mammals
around the world. The kinds of mammals destined to be dominant in this way have originated, he
wrote, in the great Eurasian landmass of the north temperate zone, roughly present-day England all the
way to present-day Japan. Being competitively superior, they eliminated older, formerly dominant
groups that had occupied the same niches. The early rulers were not extinguished entirely, however.
They still flourished in areas not yet colonized by the newcomers. Think of the present great northern
landmass formed by Europe, northern Asia, and North America as the hub of a wheel. To the south,
Matthew said, tropical Asia to Africa, Australia, and Central and South America are the spokes of the
wheel. Dominants originate in the hub and spread through the spokes. At the time of his account,
Matthews theory seemed to fit the facts.
The dominant groups of the North, Matthew went on, are superior because they evolved in rugged,
severely seasonal climates, which required a general toughness and ability to adapt to change. These
most recent winners include animals familiar to all Eurasians and North Americans: mice and rats
(taxonomic family Muridae), deer (Cervidae), cattle (Bovidae), weasels (Mustelidae), and, of
course, us (Hominidae). Former dominants, now confined to the southern spokes, are the rhinoceroses
(Rhinoceratidae), elephants (Elephantidae), and primates exclusive of man.
Right or wrong, and by evidence available in Matthews time it seemed right (although much less
so now), I saw the theory as prehistory on a global scale. It was biology lifted to the maximum in
space and time. And it was scientific natural history, the subject I had chosen!
In 1948 Philip J. Darlington, whom years later I was to succeed as curator of insects at Harvards
Museum of Comparative Zoology, presented a different story for the reptiles, amphibians, and
freshwater fishes, no less grand than that of Matthews for mammals. These cold-blooded vertebrates,
he said, arose not in the north temperate zone as supposed by Matthew for the warm-blooded
mammals, but in the vast tropical forests and grasslands that once covered most of Europe, northern
Africa, and Asia. They then spread south into the peripheral continents, much reduced in diversity of
species, and northward into the north temperate zone. It also turned out from the new wave of fossil
research that humanity originated not in Eurasia but in the tropical savannas of Africa.
I was raised, so to speak, more on Darlington than on Matthew, but Matthew I found to be right in
one important respect. There was indeed a global pattern of dominant groups arising in large,
ecologically varied portions of the worlds landmass.
Then came the equally grand theory of the World Continent Fauna, the existence of which
supported the overall theme developed by both Matthew and Darlington. For tens of millions of years
South America was isolated from North America by a broad seaway that submerged the present-day
Isthmus of Panama, thereby connecting the Pacific Ocean to the Caribbean Sea and isolating the
continents on either side. Mammals, except bats, as a rule could not cross the broad stretch of ocean
water. As a result those in South America evolved independently from those in North America. But
the two faunas converged in outward appearance and in the niches they filled. In the north there were
horses, in the south horselike litopterns. The rhinos and hippos of the north were duplicated, roughly,
by South American toxodonts, and tapirs and northern elephants respectively by southern
astrapotheres and pyrotheres. Shrews, weasels, cats, and dogs were matched in varying degree by the
diverse members of the South American family Borhyaenidae. The fearsome saber-toothed tiger of
North America was approached in overall appearance by an equivalent in South America, even
though they remained very different in another way: the northern saber-tooth was a placental (fetus
carried throughout in the uterus) and the South American one was a marsupial (fetus carried part of
the way in an outside pouch).
This evolutionary convergence was the greatest on the land that the world has ever seen. Imagine
that we could travel back in time to South America as it was ten million years ago and make a safari
across its savanna, much as tourists do today in East Africa:
Say we are there back then on the edge of a lake, early one sunny morning, turning our gaze
slowly through a full circle. The vegetation looks much like modern savanna. Out in the water
a crash of rhinoceros-like animals browse belly-deep through a bed of aquatic plants. On the
shore something resembling a large weasel drags an odd-looking mouse into a clump of
shrubs and disappears into a hole. A creature vaguely like a tapir watches immobile from the
shadows of a nearby copse. Out of the high grass a big, catlike animal suddenly charges a
herd ofwhat?animals that are not quite horses. Its mouth is thrown open nearly 180
degrees, knife-shaped canines projecting forward. The horse look-alikes panic and scatter in
all directions. One stumbles, and . . .
This independent kingdom of wildlife disappeared over a million years ago, long before the arrival
of human beings, while its North American equivalent persisted mostly intact until only about ten
thousand years ago, after skilled human hunters arrived and began to spread over the continent. Each
appeared to have reached a balance within its own domain. Why, then, did the southern kingdom
decline while the northern kingdom lived on?
This obvious disparity in survival brought biogeographers to the interesting question implied by the
balance of nature: What happens when two full-blown, closely similar dynasties meet head-on? If it
were possible to play God with geological spans of time to wait and watch, the ideal experiment
would be this: Allow two isolated parts of the world to fill up with independent adaptive radiations
of plants and animals, so that the majority of species in each theater have close ecological equivalents
in the other theater; then connect the two regions with a bridge and see what happens. When the
organisms intermingle, would those from one theater replace the other, so that a single fauna and flora
comes to occupy the entire range?
The grand experiment has in fact been performed once in relatively recent geological time, and we
can deduce a great deal of what happened by comparing fossil and living species. Two and a half
million years ago the Isthmus of Panama rose above the sea, bridging the ancient Pacific-to-
Caribbean seaway and allowing the mammals of South America to mingle with the mammals of North
and Central America. Species from each continent spread into the other.
The change in biodiversity that occurred can best be measured at the taxonomic level of the family.
Examples of mammalian families are the Felidae, or cats; Canidae, dogs and their relatives; Muridae,
the common mice and rats; and of course Hominidae, human beings. The number of mammalian
families in South America before the interchange was thirty-two. It rose to thirty-nine soon after the
Isthmus of Panama connection, and then subsided gradually to the present-day level of thirty-five. The
history of the North American fauna was closely comparable: about thirty families before the
interchange, rising to thirty-five, and subsiding to thirty-three. The number of families crossing over
was about the same from both sides.
When all this information was put together, the stage was set for another kind of theory. When
biologists see a number go up following a disturbance and then fall back to the original level, whether
body temperature, density of bacteria in a flask, or biological diversity on a continent, they suspect
that an equilibrium exists in the system. The restoration of the numbers of mammalian families in both
North and South America points to such a balance of nature. In other words, there appears to be a
limit to diversity, in the sense that two very similar major groups cannot coexist in their fully radiated
condition. A closer examination of the ecological equivalents on both continents, dwellers in the
same broad niche, reinforces this conclusion. In South America marsupial big cats and smaller
marsupial predators were replaced by their placental equivalents. Toxodonts gave way to tapirs and
deer. Still some unusual specialiststhe wild cardswere able to persist. Anteaters, tree sloths, and
monkeys continue today to flourish in South America, while armadillos are not only abundant
throughout tropical America but are represented by one species that has expanded its range throughout
the southern United States.
In general, where close ecological equivalents met during the interchange, the North American
elements prevailed. In this part of the world at least, Matthews theory was vindicated. The North
American mammals also attained a higher degree of diversification, as measured by the number of
genera. A genus is a group of related species and a group of genera is a family. The genus Canis, for
example, comprises domestic dogs, wolves, and coyotes; other genera in the dog family Canidae
include Vulpes (foxes), Lycaon (African wild dogs), and Speothos (South American bush dogs).
During the interchange, the number of genera rose sharply in both North and South America and
remained high thereafter. In South America it began at about seventy and has reached 170 at the
present time. The swelling of numbers has come principally from speciation and radiation of the
World Continent mammals after they arrived in South America. The old, pre-invasion South
American elements were not able to diversify significantly in either North or South America. So the
mammals of the Western Hemisphere as a whole now have a strong northern cast. Nearly half of the
families and genera of South America belong to stocks that have immigrated from North America
during the past 2.5 million years.
Why did the northern mammals prevail? No one knows for sure. The answer has been largely
concealed by complex events imperfectly preserved in the fossil recordthe paleontologists
equivalent of the fog of war. The question remains before us, part of the larger unsolved problem
toward which our understanding of dynastic succession is directed. Evolutionary biologists keep
coming back to it compulsively, as I did one night while camping at Fazenda Dimona, in the Brazilian
Amazon, surrounded by mammals of World Continent origin. What comprises success and
dominance?
Success in biology is an evolutionary idea. It is best defined as the longevity of a species with all
its descendants. The longevity of the Hawaiian honeycreepers will eventually be measured from the
time the ancestral finchlike species split off from other species, through its dispersal to Hawaii, and
finally to that time when the last honeycreeper species ceases to exist.
Dominance, in contrast, is both an ecological and evolutionary concept. It is best measured by the
relative abundance of the species group in comparison with other, related groups, and by the relative
impact it has on the life around it. In general, dominant groups are likely to enjoy greater longevity.
Their populations, simply by being larger, are less prone to sink all the way to extinction in any given
locality. With greater numbers, they are also better able to colonize more localities, increasing the
number of populations and making it less likely that every population will suffer extinction at the
same time. Dominant groups often are able to preempt the colonization of potential competitors,
reducing still further the risk of extinction.
Because dominant groups spread farther across the land and sea, their populations tend to divide
into multiple species that adopt different ways of life: dominant groups are prone to experience
adaptive radiations. Conversely, dominant groups that have diversified to this degree, such as the
Hawaiian honeycreepers and placental mammals, are on average better off than those composed of
only a single species: as a purely incidental effect, highly diversified groups have better balanced
investments and will probably persist longer into the future. If one species comes to an end, another
occupying a different niche is likely to carry on.
The mammals of North American origin proved dominant as a whole over the South American
mammals, and in the end they remained the more diverse. Over two million years into the interchange,
their dynasty prevails. To explain this imbalance, paleontologists have forged a widely held theory,
an evolutionary-biologist kind of theory, in other words a rough consensus consistent with the largest
number of facts. The fauna of North America, they note, was not insular and sharply different like that
of South America. It was and remains part of the World Continent Fauna, which extends beyond the
New World to Asia, Europe, and even Africa. The World Continent is by far the larger of the two
landmasses. It has tested more evolutionary lines, built tougher competitors, and perfected more
defenses against predators and disease. This advantage has allowed its species to win by
confrontation. They have also won by insinuation, like raccoons and pack-forming wild dogs; many
were able to penetrate sparsely occupied niches more decisively, radiating and filling them quickly.
With both confrontation and insinuation, the World Continent mammals gained the edge.
The testing of this theory, first conceived on a rough grand scale by William Diller Matthew and
Philip Darlington, has just begun. Right or wrong, whether decisive in empirical support or not, its
pursuit alone promises to link paleontology in interesting new ways to ecology and genetics. That
synthesis will continue as the study of biological diversity expands in widening circles of inquiry to
other disciplines, to other levels of biological organization, and across farther reaches of time. You
have a place in it if animals and plants interest you in their own right, and especially if you like epics
and the clash of worlds.
The author identifying insects at an osprey nest, Florida Keys, March 19, 1968. Photograph by Daniel Simberloff.
Nineteen
THEORY IN THE REAL WORLD
IT MAY SEEM to you that science, having grown so large and complex in fact and theory, would be a
difficult profession to enter. Perhaps you worry that most of the opportunities in research and
application are closed, that competition for the rest is tight and daunting, and most of the epics and big
pictures have been filled in. You would be wrong. The researchers of my generation and others
before you accomplished a lot. But they did not close all pathways and enter all unknown regions.
Instead, they opened new ones. In science every answer raises more questions. I will ramp up that
important truth to an exponential degree: in science every answer creates many more questions. Thus
has it ever been, even before Newton held up a prism to a sunbeam and Darwin puzzled over
variation among the Galpagos mockingbirds.
It was also Newton who famously said, for all scientists into the future, If I see further than others,
it is by standing on the shoulders of giants. I will now tell you a story of shoulders and giants.
It could begin at any one of several times, but I will start on December 26, 1959, at the annual
meeting of the American Association for the Advancement of Science, in Washington, D.C., when a
mutual friend introduced me to Robert H. MacArthur. Robert (he resisted being called Bob) and I
were relatively young. He was twenty-nine and I was thirty. We were both very ambitious, each
searching self-consciously for the opportunity to make a major advance in science. MacArthur was
brilliant. He was widely thought the new avatar of theoretical ecology, having already made several
seminal advances. He was an avid naturalist and expert on birds, and in addition (very important in
our case) an able mathematician. Thin, sharp in face and disposition, he had an intense and withdrawn
manner that warned off fools. He was not the kind who placed hand on shoulder and slapped backs,
nor did he often laugh out loud. Although we spent a great deal of time together, MacArthur and I
never became close friends. Looking back today, I realize we never finished taking the measure of
each other.
His mentor at Yale, the first giant in this story, had been G. Evelyn Hutchinson, who was bringing
ecology into the Modern Synthesis of evolutionary biology. He was famous for the earnest brilliance
of his students. Under his tutelage, MacArthur had already made his mark by showing how complex
ecological processes such as competition in community organization and the evolution of
reproductive rates could be simplified into a form amenable to useful mathematical analysis. We
were both, ten years later, to be elected to the U.S. National Academy of Sciences, also at an
exceptionally young age. In 1972, at the peak of his creativity, MacArthur died of kidney cancer.
Science was thus stripped of his future greatness, a huge loss.
Coming together for meetings during the early 1960s, we both saw ecology and evolutionary
biology as potentially one continuous discipline filled with opportunity for innovation in theory and
field research. This was a new concept heralded by G. Evelyn Hutchinson. But we had another,
equally pressing motivation. By the 1960s, the revolution of molecular and cellular biology was
already well under way. The second half of the twentieth century was clearly going to be their golden
years, and one of the most transformative periods of all time in the history of science. Molecular
biology and cellular biology were propelled not only by the extraordinary opportunities they
provided for innovation, but also by the massive funding they received due to their obvious relevance
to medicine.
MacArthur and I understood clearly what was happening. We also saw that one negative result in
science was the proportionate downgrading of our own disciplines, ecology and evolutionary
biology. We had no equivalent of the double helix, no direct link to physics and chemistry, as did
molecular and cellular biology. Rachel Carsons seminal Silent Spring had been published in 1962,
launching the modern environmental movement, which might have provided a nourishing source of
funding equivalent to medicine, but that beneficence was still in its infancy. The new disciplines of
conservation biology and biodiversity studies did not emerge until the 1980s.
Furthermore, aside from population genetics and some very abstract principles of ecology, we had
few ideas that could be solidly linked together in the expected manner of mature natural sciences.
Molecular biologists and cellular biologists were filling faculty openings in research universities,
unconcerned about biology at the levels of the organism and of the population. In their judgment, if
they bothered to form one at all, our disciplines were old-fashioned and hopelessly unproductive. The
frontiers of biology, it appeared, had shifted decisively leftward, in the direction of physics and
chemistry. It was not so much that this new generation of biologists considered the old guard
unimportant. It was more that they expected to do a better job of the research when, someday, they got
around to it themselves. The pathways were there for MacArthur and me and other young ecologists,
but they proved difficult to follow.
My difficulties at Harvard were intensified by the fact that I was the only young tenured Harvard
professor in what was later to be called organismic and evolutionary biology. The elder and more
distinguished faculty members in the same disciplines were either wholly absorbed in tending their
personal academic gardens or else in denialaloof and disinclined to deal with the threat.
The ultimate in noblesse non oblige was the venerable George Gaylord Simpson, the second giant
in the story. He was a world authority in vertebrate paleontology and one of the authors of the Modern
Synthesis. He had devised a brilliant picture of the evolution and movement of faunas around the
world. But his withdrawal from engagement with others was legendary. Aging and ill by the time he
came to Harvard, crippled by a falling tree during a recent visit to the Amazon, he preferred to work
alone in his office deep in the bowels of the Museum of Comparative Zoology. When on one occasion
Robert MacArthur visited the Department of Biology, I made an appointment for him to see Simpson.
A meeting of first-rate minds, I thought, across the generations. I escorted him to the great mans
office, then left the two alone so as not to intrude on their conversation. (I expected to hear all about it
later anyway.) I returned to my office and began to catch up on some paperwork. Scarcely fifteen
minutes later MacArthur reappeared at my door. He hardly said a word, Robert reported. He just
refused to talk.
Simpsons taciturnity, and from my viewpoint his indifference toward addressing the intellectual
imbalance of biology at Harvard, had already played a role in the introduction of the term
evolutionary biology. In 1960, the faculty members of the Department of Biology working on
ecology and evolution, being outgunned and outfunded and soon to be outnumbered, decided to form a
committee to organize and unify our efforts. I arrived early for the first meeting, and soon was
followed by Simpson, who sat across from me (silently) to await our colleagues.
What shall we call our subject? I ventured.
I have no idea, he responded.
What about real biology? I continued, trying for humor. Silence.
Whole-organism biology?
No response. Well, those were bad ideas anyway.
There was a pause, then I added, What do you think of evolutionary biology?
Sounds all right to me, Simpson said, perhaps just to keep me quiet.
Other committee members began to file in, and when all were settled, I seized the opportunity to
assert, George Simpson and I agree that the right term for the overall subject we represent is
evolutionary biology, the name I had made up on the spot.
Simpson said nothing, whereupon our group became the Committee on Evolutionary Biology. In
time it grew to be the official Department of Organismic and Evolutionary Biology. Thus was born
the name of a scientific discipline. If there was an earlier independent birth elsewhere, and Ive heard
of none, at least the most influential use of the name was made at a time when it was most needed.
Envy and insecurity are among the drivers of scientific innovation. It wont hurt if you have a dose
of them also. For MacArthur and myself, the desire to create a new theory was reinforced by the
recognition that what we were now calling evolutionary biology, and its more quantitative
subdivision of population biology, required a rigor comparable to that of molecular and cellular
biology. We needed quantitative theory and definitive tests of the ideas spun from the theory and
vivid connections to real-life phenomena. Such hallmarks of excellence were relatively sparse in the
subjects our efforts addressed. It was time to search for them in a focused manner.
I spoke to MacArthur about islands I had visited around the world, and their use in studying the
links between the formation and geography of species. I could see that he was not thrilled by the
complexity of the subject. He became much more interested in the species-area curves that I had also
been plotting. These displayed in a simple form the geographic areas (as in square miles or square
kilometers) of islands in different archipelagoes of the world, principally the West Indies and
western Pacific, and the number of bird, plant, reptile, amphibian, or ant species found on each
island. We could see plainly that with an increase of area from one island to the next, the number of
species increased roughly to the fourth root. This means, for example, that if one island in an
archipelago is ten times the size of another in the same archipelago, it would contain approximately
twice the number of species. We also observed that islands more distant from the mainland had fewer
species than those close by.
When I talked about equilibrium I spoke of the islands near and far as being saturated.
MacArthur said, Let me think about this for a while. I trusted him to come up with something. Id
already seen evidence of MacArthurs ingenuity in breaking down complex systems into simpler
ones.
MacArthur soon wrote a letter to me in which he postulated the following:
Start with an empty island. As it fills up with species there are fewer species available from
other islands to arrive as immigrants, and so the rate of immigration falls. Also, as the island
fills up with species, it becomes more crowded and the average population size of each
species decreases. As a result the rate of species extinction rises. Therefore, as the island fills
up, the immigration rate falls, and the extinction of the species already present rises. Where
the two curves cross, the extinction rate equals the immigration rate, and the number of
species is at equilibrium.
To continue, on small islands the crowding of the species is more severe, and the extinction rate
curve is steeper. On distant islands, immigration is less, and the immigration curve less steep. In both
cases the result is a smaller number of species at equilibrium.
In 1967, MacArthur and I applied this simple model with every scrap of data on related subjects in
ecology, population genetics, and even wildlife management we could find, and fitted it together, as
best we could, in The Theory of Island Biogeography. The book enjoyed and continues to enjoy
considerable influence in the disciplines from which it was constructed. It also played a role in the
creation of the new discipline of conservation biology during the decades to follow. It was a good
example of the principle Ive urged you to remember: in research define a problem as precisely as
possible, and choose if need be the one or two partners needed to solve it.
Even so, I wasnt completely satisfied with our product. I asked myself even while it was
unfolding, how can we put such theory to a test? The equilibrium we envisioned might require
centuries to achieve. So, how does one conduct an experiment with Cuba, Puerto Rico, and the other
islands of the West Indies? One doesnt. Instead one looks for another, more tractable system. You
may recall another principle of scientific research I offered you in an earlier letter. It is that for every
problem there exists a system ideally suited for its solution. In biology the system is usually an
organism of a particular species, such as the bacterium Escherichia coli for problems in molecular
genetics. I was looking for something located higher in the scale of biological organization. I needed
an ideal ecosystem.
I was driven by two intense desires. I wanted to go on working on islands, whatever the excuse.
And I wanted to do something radically new in biogeography. I reasoned that I might accomplish both
if I chose an ecosystem small enough to be manipulated.
A solution then presented itself. Insectsmy specialtyare almost microscopic in size compared
to the mammals, birds, and other vertebrates that had been featured in earlier biogeographic studies.
They weigh a few milligrams or less, where vertebrates are measured in grams or more. There are
large numbers of tiny islands on which insects can live and breed for generations. Instead of just one
or several islands the size of Cuba, Barbados, or Dominica, where birds and mammals can be
studied, there are hundreds of thousands of islands around the world with an area of a hectare or less.
Somehow, I thought, the insect, spider, and other invertebrate faunas of a few could be altered so that
the rates of immigration and extinction onto them could be measured. From these data multiple tests
could be devised to test hypotheses, to evaluate theory itself, and to discover new phenomena.
A new world opened in my imagination. I saw the islets of the world as the perfect model
ecosystem. Now I sought a laboratory. It had to be a cluster of little islands, variously big and small,
close and distant. Where might such an ideal micro-archipelago be? I scanned detailed maps of the
eastern Atlantic and southern Gulf Coast of the United States, from the rocky prominences of Maine
and the Harbor Islands of Boston to the barrier islands of the Carolinas, Georgia, Florida, and the
Gulf states to the west. All could be reached in a days travel from Harvard University. It did not take
long to settle on the multitudinous tropical islands of the Florida Keys and Florida Bay.
To conduct experiments that would yield what scientists like to call robust conclusions, I needed
to have my islets start from zeroempty, harboring no insects at all. My attention fixed on the small,
wave-washed islands of the Dry Tortugas, the outermost cluster of the Florida Keys. Except for Fort
Jefferson at the very end, they are almost all desert islands, harboring only small patches of
vegetation and relatively few species of insects and other invertebrates in residence. There was an
advantage to their simplicity: whenever a hurricane crosses over them, they are swept clean of
terrestrial life.
In 1965 I took a team of graduate students with me to the Dry Tortugas to look over the situation.
We mapped every plant on several of the islands and recorded every insect and other invertebrate
species we could find. During the next hurricane season, in 1966, not one but two hurricanes crossed
the Dry Tortugas. We returned soon thereafter, and sure enough, the small islands were bare of plants
and terrestrial animals.
It seemed that the main problem had been solved, but by this time I had begun to have doubts about
using the Dry Tortugas. I believed that in order to conduct a high-quality experiment of lasting value,
the kind that others could replicate conveniently, I needed a better laboratory. I wanted more islands
than those that make up the Dry Tortugas. I needed to conduct the removal of the species myself, and
not rely on random weather. It would also be best to use controlsislands closely identical to the
experimental set, and treated the same but without removing the animals. Finally, I needed more
biology. The faunas of the Dry Tortugas are so small and the life spans of the ecosystems so short as
to reduce their faunas and floras to random number generators. I needed larger faunas more typical of
natural ecosystems, and I needed less disturbed islands.
Before telling you how the goal was accomplished, I will pause to reinforce a point I made earlier:
that successful research doesnt depend on mathematical skill, or even the deep understanding of
theory. It depends to a large degree on choosing an important problem and finding a way to solve it,
even if imperfectly at first. Very often ambition and entrepreneurial drive, in combination, beat
brilliance.
I was determined to solve this problem of biogeography, and was excited by the challenge of
developing a new technology doing it. I found what I needed in the small mangrove islands of Florida
Bay, just to the north of the Dry Tortugas. There are a lot of them: consider the implication of the
archipelago at the northern end of the bay called the Ten Thousand Islands. The damage done to the
entire Florida Bay mangrove system by removing the invertebrates from a dozen or so would be
negligible, and soon repaired.
At this point I enlisted the collaboration of Daniel S. Simberloff, one of my graduate students with
a strong background in mathematics. I quickly realized I had chosen a partner wisely. As with
MacArthurs work, Simberloffs mathematics fitted my own natural history nicely. From this point
forward, while facing the unknown together, we became more colleagues than teacher and student.
Together, step by step, we worked out the method of removing all of the invertebrate animals from the
mangrove islets without damaging the trees and other vegetation. Without detailing our failures and
false starts to you here, we devised the simple and straightforward method of eradication: hire a pest
control company to erect a tent over each island and fumigate it. That was not as easy as it sounds.
Working as a team, we had to invent the right framework to be erected in shallow water and find the
right kind and dosage of dispersible insecticide to use. We had to walk through gluelike muck, and
convince the workers helping us that the ground sharks swimming in close to the islands at high tide
were harmless.
Not least, Simberloff and I also had to create a network of experts on the various groups of
invertebratesbeetles, flies, moths, barklice, spiders, centipedes, and so onin order to identify the
species correctly.
After two years of monitoring the immigrations and extinctions that followed, and to my great relief
(and Simberloffs alsohe had to get a Ph.D. thesis out of his part of the work), the recolonization
fitted the equilibrium model. We also learned a great deal about the colonization process itself. I
found the whole of the adventure, from theory to experiment, one of the most satisfying experiences of
my entire scientific life.
I hope that in your own career you will see one or more opportunities of this kind and, like Daniel
Simberloff and myself, find the risk worth taking. We stood on the shoulders of giants and were able
to see a little bit farther.
V
TRUTH
and
ETHICS
The U.S. National Medal of Science.
Twenty
THE SCIENTIFIC ETHIC
I HAVE COME TO the end of my counsel to you, and will now close these letters with advice on proper
behavior in the conduct of your research and publication.
You are not likely to be directly pressed during your career on such largely philosophical
questions as the propriety of creating artificial organisms or conducting surgical experiments on
chimpanzees. Instead, by far the greatest proportion of moral decisions you will be required to make
is in your relationships with other scientists. Entrepreneurial endeavor beyond the level of puttering
creates difficulties other than the mere risk of failure. It will put you into a competitive arena for
which you may not be emotionally prepared. You may find yourself in a race with others who have
chosen the same track. You will worry that someone better equipped and financed will reach the goal
before you. When multiple investigators create an important new field simultaneously, they often
create a golden period of excited cooperation, but in later stages, as different groups follow up on the
same discoveries, some amount of rivalry and jealousy is inevitable. For you, if successful, there will
be gentle competitors and ruthless competitors. There will be gossip and some protective secrecy.
That should come as no surprise. Business entrepreneurs suffer when competitors beat them to the
marketplace. Should we expect scientists to be different?
Original discoveries, to remind you, are what count the most. Let me put that more strongly: they
are all that counts. They are the silver and gold of science. Proper credit for them is therefore not
only a moral imperative, but vital for the free exchange of information and amity within the scientific
community as a whole. Researchers rightly demand recognition for all their original work, if not from
the general public then from colleagues in their chosen field. I have never met another scientist who
was not pleaseddeeply pleasedby a promotion or award bestowed for original research. As the
actor Jimmy Cagney said of his career in motion pictures, Youre only as good as people say you
are.
The great scientist who works for himself in a hidden laboratory does not exist. Therefore, be
rigorous in reading and citing literature. Bestow credit where it is deserved, and expect the same
from others. Honest credit carefully given matters enormously. Recommending a colleague for
awards or other forms of recognition is a relatively uncommon form of altruism when practiced
among scientists. Even if it proves difficult, do not shrink from taking that step. On the other hand,
granting it to a rival, especially one you do not like and at the risk of your own recognition, would be
true nobility. It is not expected of you. Let others make the nomination. Instead just grit your teeth and
extend your congratulations.
You will make mistakes. Try not to make big ones. Whatever the case, admit them and move on. A
simple error in reporting or conclusion will be forgiven if publicly corrected. (At least one leading
journal has a special erratum section.) An outright retraction of a result will not cause permanent
harm if done graciously, and especially with thanks to the scientist who reported the error with
evidence and logical reasoning. But never, ever will fraud be forgiven. The penalty is professional
death: exile, never again to be trusted.
If youre not sure of a result, repeat the work. If you dont have the time or resources to do so, drop
the whole thing or pass it on to someone else. If your facts are solid, but youre not sure of the
conclusion, just say as much. If you do not have the opportunity or resources to repeat and confirm
your work, dont be afraid to use words denoting timid uncertainty: apparently, seemingly,
suggests, could possibly be, raises possibility of, may well be. If the result is worthwhile,
others will either confirm or disprove what you think you found, and all will share credit. Thats not
sloppiness. Its just good professional conduct, true to the core of the scientific method.
Finally, remember that you enter a career in science above all in the pursuit of truth. Your legacy
will be the increase and wise use of new, verifiable knowledge, of information that can be tested and
integrated into the remainder of science. Such knowledge can never be harmful by itself, but as
history has so relentlessly demonstrated, the way it is twisted can be harmful, and if such knowledge
is applied by ideologues, it can be deadly. Be an activist as you deem necessaryand you can be
highly effective with what you knowbut never betray the trust that membership in the scientific
enterprise has conferred upon you.
Acknowledgments
As in many of my earlier books, I am happy to acknowledge with gratitude the guidance and
encouragement of my literary agent, John Taylor Williams, and my editor, Robert Weil. I also wish to
acknowledge the expertise and essential dedicated hard work of my assistant, Kathleen M. Horton.
Photograph Credits
Frontispiece: Photograph by Alex Harris.
Photograph by Howard I. Spero.
Boy Scout Handbook, 4th ed. (1940), p. 643, Zoology badge emblem.
Paul Wiegert.
Painting by Dana Berry of the Space Telescope Science Institute.
English Heritage Images.
Modified from The political blogosphere and the 2004 U.S. election: divided they blog, by
Lada A. Adamic and Natalie Glance, Proceedings of the 3rd International Workshop on Link
Discovery (LinkKDD05) 1: 3643 (2005).
Drawing by Tom Prentiss. Modified from Pheromones, by Edward O. Wilson, Scientific
American 208(5): 110104 (May 1963).
Photograph by John Hoyle.
Piotr Naskrecki.
Photograph by NASA/JPL-CALTECH/ASU/UA.
Brian Kobilka.
Collected by Stefan Cover in Peru. Imaged by Christian Rabeling.
Barrett Klein, Biology Department, University of WisconsinLa Crosse (www.pupating.org).
W. Ford Doolittle, Phylogenetic classification and the universal tree, figure 3, Science 284:
2127 (June 25, 1999).
Catherine E. Wagner , Luke J. Harmon, and Ole Seehausen, Nature 487: 366369 (2012).
doi:10.1038/nature11144.
Klaus Bolte.
Abigail Lingford.
Drawing by Tom Prentiss (moths) and Dan Todd (active space of gyplure Scientific
American). Modified from Pheromones, by Edward O. Wilson, Scientific American 208(5):
100114 (May 1968).
Michael R Long Natural History Museum Picture Library, London.
Photograph by Daniel Simberloff.
U.S. National Medal of Science. Government property in the public domain.
About the Author
Edward Osborne Wilson is generally recognized as one of the leading biologists in the world. He is
acknowledged as the creator of two scientific disciplines (island biogeography and sociobiology),
three unifying concepts for science and the humanities jointly (biophilia, biodiversity studies, and
consilience), and one major technological advance in the study of global biodiversity (the
Encyclopedia of Life). Among more than one hundred awards he has received worldwide are the U.S.
National Medal of Science, the Crafoord Prize (equivalent of the Nobel, for ecology) of the Royal
Swedish Academy of Sciences, the International Prize of Biology of Japan, and, in letters, two
Pulitzer Prizes in nonfiction, the Nonino and Serono Prizes of Italy, and the International Cosmos
Prize of Japan. He is currently Honorary Curator in Entomology and University Research Professor
Emeritus, Harvard University.
Copyright
Frontispiece: The author at Gulf Shores, Alabama.
Photograph by Alex Harris.
Copyright 2013 by Edward O. Wilson
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