A Simple Test for the Existence of Continental Races in Homo Sapiens

Neoracialists insist that if we apply the same scientific standards to our species as we apply to other species we will find that like most species in the animal kingdom, humans too have subspecies. It is true that systematists recognize subspecies in many animal species. Chimps are a famous instance. But systematists have not recognized subspecies in Homo sapiens for decades. Is it because of they have let politics interfere with science, as the neoracialists claim? Or is it because scientists are convinced that our species does not have subspecies? And do they have good reasons for thinking that? After all, whatever the politics, that there may be subspecies in Homo sapiens is a scientific hypothesis.

The dominant process of speciation in the animal kingdom has been well understood since Ernst Mayr’s work at mid-century. Despite the promise of the title, Darwin’s The Origin of Species had failed to provide a compelling mechanism of speciation. Mayr showed that speciation is essentially a process whereby geographically isolated populations diverge from each other until they acquire isolating mechanisms (eg, different mating calls). This is called allopatric speciation. This is a process; not an event. The test is what happens when the ranges of such isolated populations overlap. If they do not interbreed and occupy different niches so that they can exist sympatrically, they are described as good species. If they show marked differentiation but still interbreed in the wild, they are described as allopatric subspecies or continental races. If they can interbreed but rarely do so and cannot exist sympatrically (say if they occupy the same niche) they are called allospecies. So allospecies is the halfway house between allopatric subspecies and good species. With these definitions, Upper Pleistocene hominin taxa are best regarded as subspecies or at worst allospecies. They were certainly not good species since we know Sapiens interbred with them and coexisted with them for at least ten thousand years (40-30ka in Europe).

What about the alleged extant races of man? The usual proof of nonexistence offered by scientists is that racial taxonomy explains a negligible portion of human genetic and phenotypic variation. The game was initiated by Lewontin’s famous intervention in 1972, “The Apportionment of Human Diversity“. He showed that 6.3 percent of human genetic variation is accounted for by racial taxonomy. Moreover, 85 percent is within ethnic groups (racial anthropologists’ “subraces”). So it’s pretty much a useless fiction. More recently, Templeton (2013) revisited the question and explicitly compared humans and chimps. Table 1 reproduces his estimates. The numbers make it obvious that there is ample reason to recognize subspecific taxa in chimps but not in humans.

Table 1. Apportionment of genetic diversity in humans and chimpanzees. 
Species Number of “Races” Number of populations Among individuals within populations (%) Among populations within races (%) Among races (%)
Chimpanzees 3 5 64.2 5.7 30.1
Humans 5 52 93.2 2.5 4.3
Source: Templeton (2013).

In what follows, I will offer a more compelling test of the existence of continental races. In the previous dispatch I demonstrated that dental polymorphisms contain an extraordinarily strong population history signal. If there are continental races in man, then these must map onto the phylogeny obtained from physical anthropology. Figure 1 shows the first and second principal components obtained from Turner’s data on dental polymorphisms. It’s clear that Turner’s Sundadonts (Southeast Asians and Polynesians) and Sinodonts (Northeast Asians and Americans) cluster together, as do the Africans and west Eurasians (Europe, India and the Middle East). Also, Melanesians and Australians cluster together but far from New Guineans. These roughly correspond to the big continental races proposed by racial taxonomists from Coon to Wade: Caucasoid, Negroid, Mongoloid, Australoid, although Sundadonts have not been recognized as such by any authority to my knowledge. Still, we will not change anything by hand. Let the data speak!

DentalPCA.png
Figure 1. First two principal components of variation in dental polymorphisms.

The phylogram obtained for these (admittedly broad) “races” is displayed in the next figure. It’s a reduced form version of the more fine-grained one we derived in the previous dispatch and consistent with all the evidence from archaeology, linguistics, and physical anthropology. What it reflects is the peopling of the world and genetic isolation over thousands of years. If these aren’t races, there aren’t any.

PhyloRaces.png
Figure 2. High level phylogeny. Source: (Turner 2018), author’s computations.

So, the test. If this “racial” taxa obtained from the slowest-moving and least confounded variables deserve subspecific status, then other systematic variation in human biology should map onto this classification. More precisely, phenotypic characters cannot be properly described as “racial” if they yield maps that are inconsistent with each other. For instance, skin reflectance does not map onto this classification since northern populations across these taxa are depigmented while low latitude populations are strongly pigmented. Okay, so skin reflectance is not diagnostic and that’s been understood for a long time. Like many other species, Sapiens obey Gloger’s Rule — pigmentation falls in high latitudes and rises in low latitudes. Even Aristotle knew this!

I am instead going to look at RBC polymorphisms. Blood groups are known to vary systematically. Famous neoracist Rushton made a big fuss about small differences in mean frequencies of blood groups between his three races (White, Black, and Asian; obviously). Well, let’s see if there is anything to it.

If these taxa are deserving of subspecific status then this systematic variation should map onto our classification, particularly since we are working at such an absurdly coarse level of analysis. If it does not even work here, then the case for awarding subspecific status to these taxa is really tenuous. Table 2 displays the frequencies of blood types for our taxa.

Table 2. Frequencies of blood groups.
Africa Western Sundadont Sinodont Sahul
O+ 0.45 0.36 0.39 0.50 0.40
A+ 0.27 0.32 0.26 0.28 0.31
B+ 0.18 0.14 0.28 0.14 0.08
AB+ 0.04 0.05 0.06 0.04 0.02
O- 0.03 0.05 0.00 0.03 0.09
A- 0.02 0.05 0.00 0.01 0.07
B- 0.01 0.02 0.00 0.00 0.02
AB- 0.00 0.01 0.00 0.00 0.01
Source: https://www.babymed.com/pregnancy/blood-type-and-rh-rhesus-status-countries.

We can see that there is significant systematic variation in the frequency of blood groups. If the taxa deserve to be recognized as subspecies then the distances obtained from RBC polymorphisms should yield similar phenotypic distances to that obtained from dental polymorphisms (which we know contains the strongest phylogenetic signal). The basic test for the similarity of distance metrics is the Mantel test. If the distance matrices are similar the P-value of the Mantel test statistic should be close to zero (0.05 is the usual standard of significance). Table 3 displays the test results.

Table 3. Mantel tests. 
Pearson Spearman
Statistic -0.569 -0.405
P-value 0.958 0.913
Source: Turner (2018), author’s computations.

So our racial taxonomy fails catastrophically. This is generally the case for most so-called racial characters. There is plenty of systematic variation in phenotypic characters. But they don’t map onto each other. (Are gingers a race?) If there were actual continental races in Homo sapiens, the world would look very different. And this is no hypothetical. For there were in fact continental races of man for most of our evolutionary history (Neanderthals, Denisovans, and so on). We mercilessly wiped them off the face of the earth like all the other megafauna of the Upper Pleistocene. Make no mistake: Our race is the most dangerous species to have ever walked on this planet.

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