I can’t get my head round genetic racism. I don’t mean why people believe comforting rubbish, that’s easy to understand. I mean: what exactly is the proposition? “Blacks are naturally dumber than whites” doesn’t hack it. “Dumber” is usually defined as “scoring lower on IQ tests”. There’s a whole argument about the relevance of IQ, and its malleability as shown by the Flynn effect, but it is a reproducible test with a fair correlation with other sorts of mental skills, so the meaning is clear and I’ll let it ride for the sake of the argument. But just who are “blacks” and “whites”, in multi-ethnic populations like that of the USA with a long history of miscegenation? My genetic knowledge is pretty thin, but it may be interesting to see how far you can get on the genuine science with Wikipedia articles, until someone with real expertise shows up.
There is no black race. Africa is the origin of humanity and its inhabitants are genetically diverse; more so than those of the continents colonised later by subgroups of African migrants and their descendants, including those transported by force like black Americans and white Australians. Further, dark skin is the human baseline. We acquired it at latest when hominids emerged from tropical forests about 1.2m BP and became biped hunter-gatherers on open savannah. Our ancestors lost their body hair, and acquired the genes for copious skin melanin that protected them from UV radiation and melanoma. Our great ape cousins the chimpanzees have pale skin under their body hair. (Curiously, the equally forest-dwelling and furry bonobos and gorillas have dark skin, for no obvious reason.)
The selective pressure on the now exposed hominids was very strong and the genetic change quite dramatic and universal, a “selective sweep” in trade lingo. There is no doubt that early homo and mulier sapiens were as black as their hominid ancestors going back a million years. That includes our oldest common ancestor (“y-chromosome Adam”) and ancestress (“mitochondrial Eve”), though there is no reason to think they were contemporaries, let alone mates.
The paler skin of Europeans, many Asiatics, and Native Americans results from mutations in the opposite direction that became advantageous as they moved to higher latitudes. These supplied less UV radiation, but increased the risk of vitamin D deficiency, rickets. Pale skin is better for vitamin D synthesis. The distribution of skin tones reflects a roughly graded balance between melanoma and rickets. These migrations started only 100,000 years ago and have continued into historical times (the Polynesian radiation) and the contemporary era (immigration into the Americas), so the adaptation has not had time to run its full course. Aboriginal Australians have darker skin than typical Indonesians and Polynesians, who live closer to the Equator but stem from a later migration wave from the Asian mainland. There is little variation in skin tone between Native Americans across their vast range in latitudes, since they only arrived 15,000 years ago (cue for academic bunfight, the migration timeline is very controversial).
There is often only one way to do a complex procedure right, and several to mess it up. The normal melanin system that produces dark skin involves several genes. Several different mutations arose that screwed up melanin production, and they are not the same in pale-skinned Europeans and Asiatics. In Europeans the known alleles involved are:
- KITLG gene – rs642742 allele, “estimated to account for 15–20% of the melanin difference between African and European populations”
- ASIP gene – rs2424984 allele
- SLC24A5 gene – rs1426654 allele, “the variant represents as much as 25–40% of the average skin tone difference between Europeans and West Africans”
- SLC45A2 gene – rs16891982 allele
- TYR gene – rs1042602 allele, also linked to paler skin in South Asia
Pale skin in East Asia (the extreme case is the porcelain white skin in the geisha ideal of beauty) evolved separately, and calls on a different set of mutations, less studied so more uncertain:
- OCA2 gene – rs1800414 allele, “shown to account for about 8% of the skin tone difference between African and East Asian populations in studies of an East Asian population living in Toronto and a Chinese Han population”
Racist genetics has to be a theory not of the inferiority of blacks but of the superiority of whites. The mutations that produced white skin must have miraculously produced higher IQ, through greater brain size or different brain development. Never mind that skin tone genes have no effect at all on eye or hair colour, so their reach into an entirely different system is implausible. Assume that the effect is possible. The scientific racist has to identify the gene or genes, and a plausible mechanism of action.
Could it be all of the mutations? IQ racists must accept that East Asians are not dumber than Europeans, according to the metric they have chosen. But their pale skin results from different genetic pathways. Two different sets of mutations must both have had the same magic effect. This is incredible.
Could it be one mutation only in each population? The mutations are common and overlap but are not universal, so there must be a large number of white Europeans and East Asians without the magic IQ gene. This should show up in a greater variance of the bell curves, once you correct for environmental variance.
The proposition looks testable. You could look at environmentally matched pairs of siblings, some with both having the hypothesised magic allele, some with one of the pair without. The magic effect should show up in a higher variance in IQ scores in the second group, and a higher mean score in the sibling with the magic allele.
The problem is getting the money for the study. It is hard to get funding for testing of highly implausible and divisive hypotheses advanced in bad faith by racist crackpots. Would it be worthwhile, as a measure of public policy, paying for the experiment in hopes of shutting the racists up? I doubt it. They would just shift their ground, as they have done before. The doctrine of white supremacy is impervious to evidence.