Anti-racist PC agendas and the American Anthropological Association's recent confirmation of the unity of the human species have led to the belief that race is a socio-political invention that promotes racism. An ironic accusation since the denial of the science behind race is what's politically motivated. Forensic anthropologist and professor of anthropology George W. Gill, whose assessments are supported by modern genetics, explains.
"First, I have found that forensic anthropologists attain a high degree of accuracy in determining geographic racial affinities (white, black, American Indian, etc.) by utilizing both new and traditional methods of bone analysis. Many well-conducted studies were reported in the late 1980s and 1990s that test methods objectively for percentage of correct placement. Numerous individual methods involving midfacial measurements, femur traits, and so on are over 80 percent accurate alone, and in combination produce very high levels of accuracy. No forensic anthropologist would make a racial assessment based upon just one of these methods, but in combination they can make very reliable assessments, just as in determining sex or age. In other words, multiple criteria are the key to success in all of these determinations.
"The 'reality of race' therefore depends more on the definition of reality than on the definition of race. If we choose to accept the system of racial taxonomy that physical anthropologists have traditionally established—major races: black, white, etc.—then one can classify human skeletons within it just as well as one can living humans. The bony traits of the nose, mouth, femur, and cranium are just as revealing to a good osteologist as skin color, hair form, nose form, and lips to the perceptive observer of living humanity. I have been able to prove to myself over the years, in actual legal cases, that I am more accurate at assessing race from skeletal remains than from looking at living people standing before me. So those of us in forensic anthropology know that the skeleton reflects race, whether 'real' or not, just as well if not better than superficial soft tissue does. The idea that race is 'only skin deep' is simply not true, as any experienced forensic anthropologist will affirm.
"Morphological characteristics...like skin color, hair form, bone traits, eyes, and lips tend to follow geographic boundaries coinciding often with climatic zones. This is not surprising since the selective forces of climate are probably the primary forces of nature that have shaped human races with regard not only to skin color and hair form but also the underlying bony structures of the nose, cheekbones, etc. (For example, more prominent noses humidify air better.) As far as we know, blood-factor frequencies [used to deny race] are not shaped by these same climatic factors.
"Those who believe that the concept of race is valid do not discredit the notion of clines, however. Yet those with the clinal perspective who believe that races are not real do try to discredit the evidence of skeletal biology. Why this bias from the 'race denial' faction? This bias seems to stem largely from socio-political motivation and not science at all. For the time being at least, the people in 'race denial' are in 'reality denial' as well. Their motivation (a positive one) is that they have come to believe that the race concept is socially dangerous. In other words, they have convinced themselves that race promotes racism. Therefore, they have pushed the politically correct agenda that human races are not biologically real, no matter what the evidence."
"A detailed genetic analysis of more than a thousand human subjects clusters them into five groups corresponding to major geographical regions. This new study shows that self-reported ancestry is a good predictor of one's genetic make-up.
"The novelty of the recent work of Rosenberg et al.  is precisely that they have checked the validity of the population-sampling approach and tried to define the genetic structure of the human population without using a priori information on the geographic origin of the individuals. For that purpose, they used the structure program, which attempts to find, for each individual, the proportion of its genome that comes from a given 'population', whose unknown genetic constitution is estimated in the same process. This procedure is performed successively with the assumption of an increasing number of 'populations' or clusters (K): K = 2, 3, 4 and so on.
"Rosenberg et al. applied this procedure to 1056 individuals analyzed for 377 autosomal short tandem repeat (STR) loci. This data set is the first outcome of the analysis of a cell-line panel of 52 worldwide populations.... The results obtained...are quite remarkable. For K = 2 case, where it is assumed that there are two clusters, a contrast is found between individuals from sub-Saharan Africa and native Amerindians. Individuals from other regions seem to harbor various proportions of 'African' genes, with a tendency to a dilution of these genes with distance from Africa.
"Assuming that three populations are present (K = 3) leads to a split of individuals found in sub-Saharan Africa from those found in Europe, North-Africa, the Middle East and Pakistan (Figure 1, barrier 2). With K = 4, a cluster of Asiatic and Oceanian individuals separates from Amerindians (Figure 1, barrier 3). With K = 5, an Oceanian cluster appears (Figure 1, barrier 4), and we are left with the pleasant picture of a world divided into genetic clusters that closely correspond to five geographic regions: sub-Saharan Africa, East Asia, Oceania, the Americas and the rest, comprising Europe, North Africa and West Asia. ... It thus seems that these five groups do correspond to major subdivisions of the human population."
Here's the chart of inferred population structure from a revised version of Rosenberg's study, in which the data set was increased from 377 polymorphisms to 993:
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