Origin of Life

HISTORICAL
DEVELOPMENT OF THE
CONCEPT OF LIFE
THE ORIGIN OF LIFE
THE ORIGIN OF LIFE
There were many theories inferred by different scientists on the origin of life.
These theories may have or may have not scientific basis. Few of these are the :
• Theory of Special Creation,
• Theory of Panspermia or the Extraterrestrial Origin,
• Theory of Spontaneous Generation,
• Theory of Evolution,
• Theory of Biogenesis,
• Deep Sea Hydrothermal Vent Theory,
• Theory of Biochemical Evolution.
THEORIES ON HOW LIFE ORIGINS
The Theory of special creation

• is at the core of most major
religions that life created by
supernatural divine forces.
• This theory accounts that God
created life as written in the
bible.
THE THEORY OF PANSPERMIA OR THE
EXTRATERRESTRIAL-
• Another possibility proposes

that cosmic dust may have
carried significant amounts
of complex organic
molecules to Earth. Nor is
life on other planets ruled
out.
THE THEORY OF SPONTANEOUS
GENERATION
• Says that life may have

evolved from inanimate matter
associated to molecules and
became complex.
• The complexity of the
molecules culminated in the
evolution of cells.
THE THEORY OF EVOLUTION
• Since forth, the time of

Charles Darwin came,
it has been through
more scrutiny for
investigation just like
the other scientific
claim.
THE THEORY OF EVOLUTION
Evolution is defined as any process of formation,

growth, or development. Charles Darwin
published a book on evolution in 1859 titled “On
the Origin of Species” which mentioned about
natural selection. He also presented great deal of
evidences that evolution occurs. The following are
the main pieces of evidence supporting evolution:
The following are the main pieces of evidence supporting evolution:
1. Species share similarities as sign of their common ancestry,
example: diverse insects have 6 legs.
2. There are progressions of species changing over time, example:
wild mustard associated with other vegetables like broccoli,
cabbage, and cauliflower.
3. Traits shown by species with remnants of past generation,
example: manatees (Trichechus manatus) are closely related to
elephants as shown by fingernails on the flippers and hair on the
body.
THE THEORY OF BIOGENESIS
• It says that living things

come from other living
things.
• This theory was developed
by Rudolf Virchow in 1858
as counterhypothesis to
spontaneous generation.
THE DEEP-SEA HYDROTHERMAL VENT
THEORY
• The deep-sea hydrothermal vent theory

proposed by Alexander Oparin and John
Haldane, mentioned the primordial soup
theory.
• Life started in a primordial soup of
organic molecules. Some form of energy
from lightning combined with the
chemicals in the atmosphere to make the
amino acids (the building block of
proteins.
THE THEORY OF BIOCHEMICAL
EVOLUTION
• The theory of biochemical

evolution proposed that at the
molecular level in organisms
had changed over a period.
• These changes caused deletions,
additions, or substitutions of
single nucleotides thus the
genomes duplicated
EARLY FORMS OF LIFE
The divergence that separated the two prokaryotic domains, Bacteria and
Archaea, occurred very rarely in the history of life, and no fossils from
before this divergence have been discovered. It has been studied that the
first form of life is believed to have appeared 3.5 billion years ago.
Paleontologists are the scientists who study fossils found microscopic
living cells known as microfossils in rocks that formed 3.5 billion years
ago after Earth cooled and solidified using radioisotope dating (which uses
radioactive materials such as the radioactive components of potassium-
argon).
The microfossils’ filaments found in
STROMATOLITES
Western Australia resemble chains of
modern photosynthetic bacteria and the
rocks in which they occur are thought to
be remains of ancient stromatolites
which are mounded, layered structure
that forms in shallow sunlit water when a
mat of photosynthetic bacteria traps
minerals and sediment. These
stromatolites increase in size over time
as new layers form over the old. These
organisms have been so abundant 1.25
billion years ago and were common
worldwide.
Many types of bacteria carry out photosynthesis, but only one group,
cyanobacteria, do so by an oxygen-producing pathway. The
microfossils of cyanobacteria were among the easiest to recognize.
The forms of these organisms were remained the same and left
chemical fossils in the form of broken products from pigments. The
first microfossil that showed remains of organisms with differences
in structure and characteristics was seen 1.5 billion years ago on the
rocks. They are bigger compared to bacteria and have internal
membranes and thicker wall. These findings marked the beginning
of eukaryotic organisms on Earth. The evolution of oxygen-
producing photosynthesis in cyanobacteria had started on early life.
About 2.5 billion years ago, oxygen released by these bacteria had
begun to accumulate in Earth’s air and creating a new, global
selection pressure. Other species considered oxygen as toxic thus
evolved gradually in its absence.
HOW DID MULTICELLULAR
ORGANISMS EVOLVE?
Multicellular organisms are believed to have evolved from unicellular
eukaryotes and until now it is the concept that we believe. Some single
eukaryotic cells, like unicellular algae, formed multicellular aggregates
through association with another cell producing colonies. From colonial
aggregates, the organisms evolved in order to form multicellular organisms
through cell specialization. Organisms like protozoans, sponges, and fungi
came to be being. The first fossilized animals which were discovered 580
million years ago were soft-bodied. The continuous process of cell
specialization brought the emergence of complex and diverse plants and
animals, including human beings. Charles Darwin said that organisms
change over time as a result of adaptation to their environment in order to
survive.
RISE OF THE EUKARYOTES
Nucleus is not often preserved during

fossilization, but other traits provide evidence
that a fossilized cell was eukaryotic. These
eukaryotic cells are generally larger than the
prokaryotic cells. A cell wall with complex
patterns, spines, or spikes probably belonged
to eukaryote. Researchers and scientists also
look for biomarkers (substance that occurs
only or predominantly in cells of a specific
type) for each eukaryote just like the steroids
found present only to eukaryotes.
EUKARYOTIC ORGANELLES AND
DESCRIPTION
END I GUESS
WELL THANKS FOR
LISTENING

Origin of Life

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HISTORICAL

The Theory of special creation

• Another possibility proposes

• Says that life may have

• Since forth, the time of

Evolution is defined as any process of formation,

• It says that living things

• The deep-sea hydrothermal vent theory

• The theory of biochemical

Nucleus is not often preserved during

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