34 Evolutionary Anthropology ARTICLES Apportionment of Racial Diversity: A Review RYAN A. BROWN AND GEORGE J. ARMELAGOS ogists and 31% of cultural anthropol- It has become increasingly popular to theorize and assert significant genetic ogists accept the validity of biological differences between arbitrary regional, ethnic, and racial groupings of humans. races in Homo sapiens.40 There are Beginning with Livingstone, Brace, and Newman is the early 1960s, biological many reasons for the decline in accep- anthropologists have shown that variation in human traits is non-concordant along tance of race as a means of under- racial lines, as they are products of overlapping, dynamic selective pressures. standing human variation. Some In 1972, Lewontin analyzed blood groups, serum protein, and red blood cell enzyme claim that anthropologists are under variants and found that only about 6% of total genetic variance was accounted for by pressure to maintain a politically cor- race, while the majority of variance is accounted for by differences between individ- rect position.41–43 However, one of the uals. Using similar assays, Latter obtained similar results in 1980. In 1982, Nei and underlying reasons for the decline is Roychoudhury analyzed 62 protein variants and 23 blood groups, finding that roughly the arbitrary nature of racial classifi- 10% of genetic variance was accounted for by race. Analyzing protein, blood group, cations: The boundaries between and HLA variants, Ryman and coworkers obtained similar figures in 1983. More races depend on the specific traits recently, Dean and coworkers (1994) and Barbujani and coworkers (1997) have used used and the classifier’s own cultural PCR techniques to analyze RFLP and microsattelite loci, again yielding estimates of norms.11,25 Other reasons include the around 10% for the amount of genetic variance accounted for by race. Furthermore, lack of correlation of traits used in recent research on regional and racial variance in mtDNA (Excoffier and coworkers, classification11,25 and the existence of 1992), a traditional marker for human racial groupings, shows a higher proportion of alternative methods for explaining hu- variance within than across racial categories. man variation. These studies used a variety of assays and analytical techniques, some of which are The success of racial classification designed to maximize the amount of variance accounted for by race. In light of this, the low depends on the number of traits used proportion of genetic variance across racial groupings strongly suggests a re-examination in ordering the races.25 A single trait of the race concept. It no longer makes sense to adhere to arbitrary racial categories, or such as skin color will result in a clas- to expect that the next genetic study will provide the key to racial classification. sification system that is easily deter- mined. Add another trait and classifi- cation becomes a more difficult task, In the last 30 years there has been have discarded it as a research and and there usually are groups that can- an assault on the race concept.1–35 teaching tool.36–39 Even use of the not be classified. As you increase the Many anthropologists question the race concept in textbooks is declin- number of traits, the problems in ra- usefulness of the race concept and ing.39 Only 50% of physical anthropol- cial classification become insur- mountable. Newman44 used genetic traits as a Ryan A. Brown is a graduate student in the Laboratory for Comparative Human Biology at means of systematically testing the va- Emory University. His main interests lie in developmental psychiatric epidemiology, with a lidity of Garn and colleagues’45,46 clas- focus on the relevance of physiologic reactivity to mental health. Brown recently returned from a summer of research on the physiology, psychology, ecology, and ethnography of diurnal sification of geographic and local sleep in Egypt. He is currently planning a one-year longitudinal study of male adolescents and races. He selected a number of traits mental health in Cairo. and systematically determined whether George J. Armelagos is Professor of Anthropology at Emory University in Atlanta, Georgia. His or not they clustered. Newman found research has focused on diet and disease in human adaptation. He has coauthored Demo- that three of the geographic races graphic Anthropology with Alan Swedlund and Consuming Passions: The Anthropology of Eating with Peter Farb. He has coedited Paleopathology at the Origins of Agriculture with Mark (Asian, Amerindian, and African) ap- Cohen and Disease in Populations in Transition: Anthropological and Epidemiological Per- peared to “stand up well,” three spective with Alan Swedlund. He has been president of American Association of Physical Anthropologists, Northeast Anthropological Association, chairman of the Biological Anthro- (Melanesian, Polynesian and Micro- pology unit of the American Anthropological Association and Chair of the Anthropology nesian) fell within the categories of Section of the American Association for the Advancement of Science. Johnnetta Cole and he “suspense account” and “may be valid are collaborating on a book entitled Conversations on Race. but the critical data is lacking,” and Department of Anthropology, Emory University, Atlanta GA 31322. three (European, Indian and Austra- E-mail: [email protected]. lian) were labeled “unwarranted ab- straction.” He commented that Garn Evolutionary Anthropology 10:34–40 (2001) and coworkers’ list of local races “har- ARTICLES Evolutionary Anthropology 35 bor[s] many conceptual left-overs the first serious attempt to determine counted for 8.3%, and individual from the days of typological thought the extent to which racial groups ac- differences 85.4%. Thus, genetic dif- in racial anthropology” (p. 192). New- count for human genetic variation. ferences between individuals have lit- man was pleased with his results and Drawing on existing studies of the dis- tle to do with racial or ethnic bound- said that with more study and the dis- tribution of various biochemical aries. covery of new genetic traits racial markers in populations around the Lewontin’s analysis was met with classification would be refined. Unfor- world, Lewontin compiled data for disbelief. It was thought that if the tunately, he appears to have missed nine blood groups (represented by dif- “correct” genetic traits were used, the implication of his analysis and the ferences in immunologic response to race would be shown to be a major issues it raises for racial studies. a specific challenge), as well as eight source of human diversity. Critics ar- Newman unwittingly had discov- serum protein and red blood cell en- gued that if Lewontin had used the ered that racial traits are nonconcor- zyme variants. In the absence of poly- right genetic markers, his results dant; that is, there is no agreement merase chain reaction technology, would have been quite different. between traits used in racial classifi- these markers acted as proxies for ac- Lewontin’s results have been repli- cation.12 If there is concordance, ev- tual genotypes; each variant was pre- cated by many studies, which in turn ery trait will result in the same classi- sumed to represent one allelic variant. have used a variety of different types fication. For concordance to occur, Lewontin used two sublevels of of data and different analytical meth- each trait must be selected for at the population structure in his analyses: ods. In 1980 Latter59 used major geo- same rate and in the same direction. races (Caucasians, Black Africans, graphical contiguity to classify six In reality, genetic traits are evolving at Mongoloids, South Asian Aborigines, “major human subgroups,” subdi- different rates and in different direc- vided these major divisions into “re- tions, and consequently become non- gions” (northern, southern, and east- concordant. In practice, racial classi- Restriction enzyme and ern), and subdivided these regions fiers have to select the genetic traits polymerase chain into populations (Greek, Zulu, and so and morphological features that sup- on). Thus, Latter added an additional port their preconceived notions of reaction techniques layer of population substructure to race. Racial lines have been drawn make obsolete use of Lewontin’s analysis. Just as Lewontin along the axes of aggression,47 sexual had done, Latter used published data behavior,48 intelligence,49–53 athletic “genetic systems” as a on 18 “genetic systems” (ten blood ability,54–58 and just about every other proxy for genotype groups, three serum proteins, and five behavioral and psychological charac- because they allow enzymes). However, in addition to the teristic one can think of. Often, these Shannon information measure, he supposed racial differences are pre- researchers to gain a used two new analytical methods for sumed to be genetic. However, there is more direct measure of quantifying genetic diversity: the pro- a major line of evidence that makes portion of shared genes between two claims about racial differences in ag- the genetic code. To randomly selected individuals and the gression, sexual behavior, intelli- many who supported probability that two randomly se- gence, and almost any other charac- lected individuals will have different teristic highly unlikely, if not the racial model, this (nonidentical) genotypes. Using these completely untenable. was the scientific three measures, 7.5% to 10.4% of ge- This evidence comes from research netic diversity was accounted for by on how human