Razib Khan One-stop-shopping for all of my content

January 23, 2018

Function & phylogeny, where the twain shall diverge

Filed under: Historical Population Genetics,Kalash,Nuristani — Razib Khan @ 11:03 pm


Every few years I get asked about Nuristanis and Kalash. The reason is that these people are often white. By white, I mean that some Nuristanis and Kalash are fair-skinned, blonde-haired, and blue-eyed. Entering “Nuristani” into Google images returns some very white faces. And you have weird news stories about ‘white’ Taliban, because non-locals don’t realize that some Nuristanis look like Northern Europeans.

Since the vast majority of people who look like white Northern Europeans are white Northern Europeans, many people assume that the Nuristanis and Kalash must have some kinship to white Northern Europeans. More precisely, many have spread the legend that these people have some relationship to the soldiers of Alexander the Great (even though Macedonians are Southern European…details).

As it turns out, they do have some kinship to Europeans…but not inordinately more than any of the other peoples of the region. The TreeMix plot at the top of this post shows that Greeks are far closer to Iranian Jews than they are to Kalash. In fact, the Kalash clearly have a non-trivial proportion of “Ancestral South Indian” South Asian ancestry.

Because of their high genetic drift (they’re endogamous and kind of inbred) a lot of population genetic analyses are a bit more difficult with the Kalash samples that are out there. But their genetic affinities are clear:

Table S4 show highly significant evidence (p value < 10−10) in the Kalash when using Armenia and Chamar as surrogates. Eight other pairings of surrogates give p values < 10−5. In all cases, the surrogate pairs include one group from South Asia (Chamar, Kol) and the other from West Eurasia (Armenia, Adygei, Brahui, Hungarians, Palestinians, Tuscans), consistent with admixture from a West Eurasian source.

Chamar are a Dalit caste of Northern India if you don’t know.

So what’s going on with the Kalash and Nuristanis? Appreciable frequencies of alleles which are correlated with traits like blue-eyes are found amongst them. Though the frequencies are much lower than in Northern Europeans. Very white looking Nuristanis and Kalash may be highly salient to photographers and the Western media, but it turns out most Nuristanis and Kalash look West Asian, with a minority who are dark-skinned enough that their South Asian ancestry is also quite clear.

This disjunction between appearance and ancestry should not surprise us. There has been a lot of recent change in physical appearance across populations over the last 10,000 years. Europeans themselves have changed in appearance. Similarly, other populations have as well. Some of them look similar to Europeans due to happenstance or convergence.

Another case are the Ainu of Japan. Though as an unadmixed group they no longer exist, old photos show some of them exhibiting an appearance not typical of East Asians. This led early anthropologists to posit that the Ainu were a “lost white race.” And yet to my knowledge, no European ancestry is found in Hokkaido, or in the Tohoku region, where Ainu-like people lived down to the early medieval period.

The moral of the story: don’t judge the contents of the book by its cover.

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