Human DNA sequences: More variation and less race
Jeffrey C. Long, Jie Li, Meghan E. Healy
Interest in genetic diversity within and between human populations as a way to answer questions about race has intensified in light of recent advances in genome technology. The purpose of this article is to apply a method of generalized hierarchical modeling to two DNA data sets. The first data set consists of a small sample of individuals (n = 32 total, from eight populations) who have been fully resequenced for 63 loci that encode a total of 38,534 base pairs. The second data set consists of a large sample of individuals (n = 928 total, from 46 populations) who have been genotyped at 580 loci that encode short tandem repeats. The results are clear and somewhat surprising. We see that populations differ in the amount of diversity that they harbor. The pattern of DNA diversity is one of nested subsets, such that the diversity in non-Sub-Saharan African populations is essentially a subset of the diversity found in Sub-Saharan African populations. The actual pattern of DNA diversity creates some unsettling problems for using race as meaningful genetic categories. For example, the pattern of DNA diversity implies that some populations belong to more than one race (e.g., Europeans), whereas other populations do not belong to any race at all (e.g., Sub-Saharan Africans). As Frank Livingstone noted long ago, the Linnean classification system cannot accommodate this pattern because within the system a population cannot belong to more than one named group within a taxonomic level.
Indeed. Of course, the Linnean classification system can't accommodate much in the natural world, either, because things don't evolve from the top down. That's why I long ago explicitly rejected the top-down Linnean approach to thinking about race in which there's a race for everyone and everyone in his race in favor of the bottom-up genealogical approach of thinking of racial groups as extended families that are partly inbred.
Understanding race and human variation: Why forensic anthropologists are good at identifying race
Stephen Ousley, Richard Jantz, Donna Freid
American forensic anthropologists uncritically accepted the biological race concept from classic physical anthropology and applied it to methods of human identification. Why and how the biological race concept might work in forensic anthropology was contemplated by Sauer (Soc Sci Med 34  107-111), who hypothesized that American forensic anthropologists are good at what they do because of a concordance between social race and skeletal morphology in American whites and blacks. However, Sauer also stressed that this concordance did not validate the classic biological race concept of physical anthropology that there are a relatively small number of discrete types of human beings. Results from Howells ... and others using craniometric and molecular data show strong geographic patterning of human variation despite overlap in their distributions. ... In this study, multivariate analyses of craniometric data support Sauer's hypothesis that there are morphological differences between American whites and blacks. We also confirm significant geographic patterning in human variation but also find differences among groups within continents. As a result, if biological races are defined by uniqueness, then there are a very large number of biological races that can be defined, contradicting the classic biological race concept of physical anthropology. Further, our results show that humans can be accurately classified into geographic origin using craniometrics even though there is overlap among groups.
In other words, for many decades, when somebody finds a skeleton buried in a shallow grave in the woods, the cops call in a forensic anthropologist from a university, who examines the bones and reports back something like: "Male, black, age between 20 and 30," which is a big help for the cops.
The point is that despite all that sophomore silliness that cultural anthropologists teach about how race doesn't exist, the forensic anthropologists usually don't have much trouble figuring out which Race box to check on the "Missing Person" ID form. In fact, they are now so good at it, that they can often tell a Swede from a Greek or whatever from the shape of the skull, supposedly "contradicting the classic biological race concept of physical anthropology," (although not my partly inbred extended family model).
Race reconciled?: How biological anthropologists view human variation
Heather J.H. Edgar, Keith L. Hunley
How race becomes biology: Embodiment of social inequality
Clarence C. Gravlee
1918: Three perspectives on race and human variation
Biohistorical approaches to race in the United States: Biological distances among African Americans, European Americans, and their ancestors
Heather J.H. Edgar
Folk taxonomies of race are the categorizations used by people in their everyday judgments concerning the persons around them. As cultural traditions, folk taxonomies may shape gene flow so that it is unequal among groups sharing geography. The history of the United States is one of disparate people being brought together from around the globe, and provides a natural experiment for exploring the relationship between culture and gene flow. The biohistories of African Americans and European Americans were compared to examine whether population histories are shaped by culture when geography and language are shared. Dental morphological data were used to indicate phenotypic similarity, allowing diachronic change through United States history to be considered. Samples represented contemporary and historic African Americans and European Americans and their West African and European ancestral populations (N = 1445). Modified Mahalanobis' D2 and Mean Measure of Divergence statistics examined how biological distances change through time among the samples. Results suggest the social acceptance for mating between descendents of Western Europeans and Eastern and Southern European migrants to the United States produced relatively rapid gene flow between the groups. Although African Americans have been in the United States much longer than most Eastern and Southern Europeans, social barriers have been historically stronger between them and European Americans. These results indicate that gene flow is in part shaped by cultural factors such as folk taxonomies of race, and have implications for understanding contemporary human variation, relationships among prehistoric populations, and forensic anthropology.
In other words, "folk taxonomies" tend to be scientifically accurate.
Estimation and evidence in forensic anthropology: Sex and race
Lyle W. Konigsberg, Bridget F.B. Algee-Hewitt, Dawnie Wolfe Steadman
Forensic anthropology typically uses osteological and/or dental data either to estimate characteristics of unidentified individuals or to serve as evidence in cases where there is a putative identification. In the estimation context, the problem is to describe aspects of an individual that may lead to their eventual identification, whereas in the evidentiary context, the problem is to provide the relative support for the identification. In either context, individual characteristics such as sex and race may be useful. Using a previously published forensic case (Steadman et al. (2006) Am J Phys Anthropol 131:15-26) and a large (N = 3,167) reference sample, we show that the sex of the individual can be reliably estimated using a small set of 11 craniometric variables. .... Similarly, the known "race" of the individual is relatively uninformative in "making" the identification, because the individual was recovered from an area where the 2000 US census provides a very homogenous picture of (self-identified) race. Of interest in this analysis is the fact that the individual, who was recovered from Eastern Iowa, classifies very clearly with ... Easter Islander sample in an analysis with uninformative priors. When the Iowa 2000 Census data on self-reported race are used for informative priors, the individual is clearly identified as American White. This analysis shows the extreme importance of an informative prior in any forensic application.
In other words, there probably aren't a lot of Easter Islanders who wound up in a shallow grave in Eastern Iowa, so forensic anthropology works again!
The global pattern of gene identity variation reveals a history of long-range migrations, bottlenecks, and local mate exchange: Implications for biological race
Keith L. Hunley, Meghan E. Healy, Jeffrey C. Long
Several recent studies have argued that human genetic variation conforms to a model of isolation by distance, whereas others see a predominant role for long-range migrations and bottlenecks. It is unclear whether either of these views fully describes the global pattern of human genetic variation. In this article, we use a coalescent-based simulation approach to compare the pattern of neutral genetic variation predicted by these views to the observed pattern estimated from neutral autosomal microsatellites assayed in 1,032 individuals from 53 globally-distributed populations. We find that neither view predicts every aspect of the observed pattern of variation on its own, but that a combination of the two does. Specifically, we demonstrate that the observed pattern of global gene identity variation is consistent with a history of serial population fissions, bottlenecks and long-range migrations associated with the peopling of major geographic regions, and gene flow between local populations. This history has produced a nested pattern of genetic structure that is inconsistent with the existence of independently evolving biological races. ...
But is consistent with the existence of partly inbred extended families.
How Neandertals inform human variation
Milford H. Wolpoff
Race and global patterns of phenotypic variation
John H. Relethford
Phenotypic traits have been used for centuries for the purpose of racial classification. Developments in quantitative population genetics have allowed global comparison of patterns of phenotypic variation with patterns of variation in classical genetic markers and DNA markers. Human skin color shows a high degree of variation among geographic regions, typical of traits that show extensive natural selection. Even given this high level of geographic differentiation, skin color variation is clinal and is not well described by discrete racial categories. Craniometric traits show a level of among-region differentiation comparable to genetic markers, with high levels of variation within populations as well as a correlation between phenotypic and geographic distance. Craniometric variation is geographically structured, allowing high levels of classification accuracy when comparing crania from different parts of the world. Nonetheless, the boundaries in global variation are not abrupt and do not fit a strict view of the race concept; the number of races and the cutoffs used to define them are arbitrary. The race concept is at best a crude first-order approximation to the geographically structured phenotypic variation in the human species.
In other words, we can now go way beyond the old race concept in detail of tracking origin.