Anatomy, Medical Education and Human Ancestral Variation

J_ID: ZA9 Customer A_ID: 11-0092 Cadmus Art: ASE258 Date: 11-OCTOBER-11 Stage: I Page: 1 VIEWPOINT COMMENTARY Anatomy, Medical Education, and Human Ancestral Variation AQ1 Goran Štrkalj,1* Muhammad A. Spocter,2 A. Tracey Wilkinson3 1 Department of Chiropractic, Macquarie University, Sydney, New South Wales, Australia 2 Department of Anatomy, Des Moines University, Iowa 3 School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom It is argued in this article that the human body both in health and disease cannot be fully understood without adequately accounting for the different levels of human variation. The article focuses on variation due to ancestry, arguing that the inclusion of information pertaining to ancestry in human anatomy teaching materials and courses should be carried out and implemented with care and in line with latest developments in biological anthropology and related sciences. This seems to be of particular importance in the education of health professionals, as recent research suggests that better knowledge of human variation can improve clinical skills. It is also argued that relatively small curricular changes relating to the teaching of human variation can produce significant educational gains. Anat Sci Educ 00: 000-000. © 2011 American Association of Anatomists. Key words: gross anatomy education; medical education; health care education; human variation; race; anthropology The human body has resulted from a long and complex process of evolution. According to a model (Tattersall, 2009) strongly supported by archaeological, anatomical, and genetic data, the species Homo sapiens evolved from a rather small African population which started to disperse to other parts of the world between 125,000 and 60,000 years ago. In the years following, the descendants of this original population adapted to life in different environments through the process of natural selection, diversifying morphologically as a result. This process of diversification was further mediated (heightened or lessened) through other evolutionary forces. Examples are genetic drift, where allele frequencies are changed due to chance alone, and gene flow between populations due to migrations which have characterized most of human history and, indeed, prehistory (Relethford, 2009). As a result, modern humans exhibit biological heterogeneity as a result of their geographic ancestry. This diversity is exceptionally complex, the complexity being further exacerbated by a variety of cultural and social factors (Relethford, 2009). *Correspondence to: Prof. Goran Štrkalj, Department of Chiropractic, Macquarie University, Sydney, 2109 NSW, Australia. E-mail: goran.strkalj@mq.edu.au Received 28 July 2011; Revised 23 September 2011; Accepted 25 September 2011. Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/(ISSN)1935-9780 © 2011 American Association of Anatomists Anatomical Sciences Education ID: nareshrao Anat Sci Educ 00:000–000 (2011) MONTH 2011 Date: 11/10/11 The existence of variations has been long observed in anatomy, but their importance has not always been fully acknowledged (e.g., Bergman et al., 1988; Bergman, 2011). It should not be forgotten that while humans differ at various levels of biological organization (individually, due to age, sex), the one briefly described above—variation due to ancestry—provoked the most intense scientific debate. (From now on the phrase ‘‘human variation’’ will be used to denote ancestral differences only). Historically the study of human biological variation has primarily fallen into the research domain of biological anthropology (Brace, 2005), but this intricate subject has in recent years been intensely investigated in several other disciplines within the social, natural, and medical sciences (e.g., Ellison and Goodman, 2006; Metrosa, 2006; Koenig et al., 2008). In medicine in particular, interest in the etiology, incidence and risk factors associated with disease has seen intense investigation of modern human variation. In spite of this, disagreement and misunderstanding as to the nature and origin of biological variation and its relation to medicine abounds (Gravlee, 2009). For a lengthy period of time race was the key concept in studying and understanding human variation. Racial divisions were based on a typological approach which reached its peak in the late nineteenth and early twentieth centuries. Typologists focused on average tendencies and tried to outline a set of defining characters that could be used to delineate races efficiently. Typology proved to be highly limiting, as it neglected ranges of variation and the complex patterns of distribution of different traits. As a result of the advances in biological sciences, and facilitated by social and political changes in the period after the Second World War, the typological Time: 08:21 Path: N:/3b2/ASE#/Vol00000/110064/APPFile/JW-ASE#110064 J_ID: ZA9 Customer A_ID: 11-0092 Cadmus Art: ASE258 Date: 11-OCTOBER-11 approach was gradually abandoned. This resulted in the reconstitution of the race concept within a populational framework, where races are seen as groups with fuzzy, overlapping boundaries. Race was utilized mainly as a descriptive device and a matter of convenience. In the 1950s and 1960s many anthropologists argued that race, in any of its meanings, had no place in the study of human variation, as it obscured more than helped to explain complex patterns of human variation. Recent research indicates that the race concept is now abandoned by a majority of Western anthropologists (Lieberman et al., 2004; Kaszycka et al., 2009). However, elements of typology still percolate into modern research. The eminent evolutionary biologist, the late Ernst Mayr argued that the key fault in understanding human variation is in relying on a typological approach, which assumes that ‘‘every member of a race has all the actual and imaginary characteristics of that race’’ (Mayr, 2002). A number of researchers (Feldman et al., 2003; Jorde and Wooding, 2004) argued for the use of the concept of ancestry instead of that of race in medical research. Ancestry relates to many lines of an individual’s geographical/regional origins. As Bolnick noted ‘‘an individual can have ancestry from multiple geographical regions, and the concept of ancestry is flexible enough that those regions can be local (e.g., southwestern Nigeria) or much broader (e.g., all of Africa)’’ (Bolnick, 2008). HUMAN VARIATION AND ANATOMY In previous publications by these authors, it was argued that many of the misunderstandings mentioned above could, at least partly, be attributed to the lack of education on the subject (e.g., Štrkalj and Wilkinson, 2006; Wilkinson et al., 2010). Indeed, it has been suggested that in anthropology, education made a significant impact on anthropologists’ attitudes toward human variation and race and that educational changes might have played an important role in the recent shift towards nonracial approaches by many anthropologists (Littlefield et al., 1982, Kaszycka and Štrkalj, 2002; Kaszycka et al., 2009). It was also maintained that it is no overstatement to suggest that many medical graduates are poorly equipped to deal with the topic of human variation and its translation into medical practice and research (Wilkinson et al., 2010). Thus, including the teaching of human variation in the medical curriculum would be helpful in clearing up many misconceptions, providing students with the insight and conceptual tools necessary to understand their patients better. Acknowledging that this is not an easy task, it could be achieved if some of the parties involved in medical education make a small, but well planned and coordinated contribution. Anatomists could and should play an important role in this process. It is, after all, in the study of human structure that a medical student becomes fully aware of the significance of human variation and its importance in understanding the human body in health and disease, probably for the first time. At present, however, it would appear that little attention is paid to variation due to ancestry and if it is, it is often done using obsolete terminology or information. A recent survey of eighteen widely used English language anatomy textbooks revealed that only four of these texts (two of which were different versions of the same book) even attempted to explain human variation (Štrkalj and Solyali, 2010). In addition, all of those that dealt with human varia2 Stage: I Page: 2 tion provided a brief, rather outdated account and were reliant on the traditional race concept. This is epitomized by the following extract: ‘‘Racial differences may be seen in the color of the skin, hair, and eyes, and in the shape and size of the eyes, nose, and lips. Africans and Scandinavians tend to be tall, as a result of long legs, whereas Asians tend to be short, with short legs. The heads of central Europeans and Asians also tend to be round and broad’’ (Snell, 2008). It is precisely the perpetuation of these anachronistic descriptions with their reliance on racial typology that hinders medical disciplines from presenting a more sophisticated and biologically informed opinion of the origins and nature of human variation to their students. Indeed, using morphological types either as explanatory devices or simply as descriptive shortcuts sends a misleading message to students. Morphological types, as noted in The Cambridge Dictionary of Human Biology and Evolution (Mai et al., 2005) were ‘‘identified or created by the classical somatologists or biotypologists’’ and ‘‘such categorical classifications have given way to recent hypotheses that appreciate more fully the continuous nature of human variation.’’ In our opinion, certain basic generalizations and facts regarding human variation have to be presented in all anatomy textbooks and communicated to students in all anatomy courses. Students must understand that humans vary morphologically due to ancestry, and that many morphological traits appear with different frequencies in different populations. This variation is the result of interplay of different evolutionary forces. At the same time, division into race, though intuitively appealing (Berreby, 2008; Yoon, 2009), is not applicable to the species Homo sapiens as ‘‘human races’’ are not natural biological groups but artificial divisions according to certain (often arbitrarily) chosen characteristics or set of characteristics (Štrkalj, 2006). Some of the traits in which humans vary might be of clinical importance (e.g., skin pigmentation: people of lighter complexion having a stronger predilection for developing skin cancer in the areas of high ultraviolet radiation than people of darker complexion). It has to be kept in mind that if any two or more of these morphological traits are analyzed, they often have different patterns of distribution between different human groups (discordant distribution). Also, the incidence of many traits often changes gradually across different geographical regions (clinal distribution) making the boundaries between different populations fuzzy, rather than well defined. These generalizations should be presented in the introductory sections of anatomy textbooks and courses, which should later be reinforced using the examples of variation when elaborating on different body systems or regions. Thus, to use the previous example, skin pigmentation is darker in people originating from regions close to the equator as a result of adaptation to life in areas of a high ultraviolet (UV) radiation. Skin color becomes lighter further away from the equator as lighter skin has higher adaptive value in areas of lower UV variation. However, one has to bear in mind that first, geographical changes in skin color are gradual (and people can only arbitrarily be divided into ‘‘black’’ and ‘‘white’’ with or without articulation of any ‘‘shades’’ in between); and second, due to constant migration, simple maps of skin color distributions are not possible. As a result, people of very light skin color, for example, now populate areas with the highest levels of UV radiation and have to resort to various cultural adaptations to protect themselves and avoid possible serious health consequences due to exposure. Štrkalj et al. ID: nareshrao Date: 11/10/11 Time: 08:21 Path: N:/3b2/ASE#/Vol00000/110064/APPFile/JW-ASE#110064 J_ID: ZA9 Customer A_ID: 11-0092 Cadmus Art: ASE258 Date: 11-OCTOBER-11 Altogether, these curricular changes would be mild annotation and upgrading of the existing texts and courses. A modicum of change could induce major improvements. Furthermore, these changes could be easily implemented by anatomists alone or with a help of biological anthropologists who could intervene directly or indirectly, through workshops or similar education programs aimed at the anatomy faculty (many big anatomy departments employ biological anthropologists to teach anatomy). However, taking into consideration the amount of material required for medical students to learn, could these relatively small additions to the medical curriculum be enough to make a real impact on students’ understanding of human variation? Recent studies have demonstrated that they can and that even a modicum of education can have a strong impact on student attitudes towards ‘‘race’’ (Štrkalj and Wilkinson, 2005; Hart and Ashmore, 2010). In studies where student opinions were elicited before and after short modules on human variation, it was observed that not only did their knowledge of human variation improve, but there was also a statistically significant shift towards discarding the traditional race concept (Štrkalj and Wilkinson, 2005; Hart and Ashmore, 2010). Furthermore, if similar small curricular changes are introduced in other basic science disciplines and are subsequently revisited in the clinical subjects, the final educational outcome is likely to be positive. It is promising to know that if student opinion can be changed significantly in this way, future medical researchers, practitioners, and educators might also modify and improve their understanding of human biological variation after similar exposure to the subject. Medical educators may then influence the next generation of practitioners and foster a greater awareness of the biological history of the communities they hope to help. Stage: I Page: 3 would also complement recent changes leading to incorporation of humanities into medical education in general, in which anatomists have played a significant role in recent years (Vannatta and Crow, 2007; Canby and Bush, 2010). NOTES ON CONTRIBUTORS GORAN ŠTRKALJ, Ph.D., is an associate professor in the Department of Chiropractic at Macquarie University in Sydney, Australia, where he teaches human anatomy to chiropractic and science students. His main research interests are in human variation and evolution, history of science and science education. MUHAMMAD A. SPOCTER, Ph.D., is an assistant professor in the Department of Anatomy at Des Moines University, Iowa, where he teaches human anatomy to osteopathic and science students. His main research interests are in comparative neuroanatomy, human evolution, variation and science education. A. TRACEY WILKINSON, M.B.Ch.B., Ph.D., is a senior lecturer in the School of Biosciences at Cardiff University in Cardiff, Wales, United Kingdom. She teaches medical, dental and science students and her research interests are in education, biomechanics, and human variation. ACKNOWLEDGMENTS The authors thank Professor Wojciech Pawlina and the three anonymous referees for their valuable comments. While these comments improved the original manuscript considerably, the authors take full responsibility for the statements made in the article and for any possible mistakes and omissions. LITERATURE CITED CONCLUSION Understanding human variation and its medical relevance and implication is of considerable importance for medical practitioners and researchers. There is no doubt that ‘‘improved medical training’’ on human variation and race ‘‘can sharpen diagnostic skills,’’ as was recently argued by Braun et al. (2007). Anatomists should start playing a more important role in this segment of medical training and contribute toward future medical professionals’ better understanding of the relevance of human variation in medical practice. It is not, of course, proposed that students should learn everything about human variation and its clinical relevance in their anatomy classes. They should be given an elementary explanation of human biodiversity and accurate information of the aspects of human variation related to anatomy, which would concur with recent advances in anthropology and related sciences. This information should be further broadened and articulated in later, clinical years of study. Small steps, if taken in the right direction, may produce significant improvements in the educational process and should, in the long run, contribute towards a better quality of medical care. 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