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[QUOTE]Originally posted by DD'eDeN: [QB] Recent article shows KhoiSan developed lightened skin recently ~ 2- 3,000 years ago from East Africans/West EurAsians. [My guess is that light skin began around the lowlands of the Dead Sea, and it spread outward, perhaps in part due to woven clothing & the cosmic impact/asteroid that hit the Dead Sea region (Sodom & Gomorrah?) about 3 - 2ka.] https://eurekalert.org/pub_releases/2018-12/uoc--rge121018.php Populations of indigenous people in southern Africa carry a gene that causes lighter skin, and scientists have now identified the rapid evolution of this gene in recent human history. The gene that causes lighter skin pigmentation, SLC24A5, was introduced from eastern African to southern African populations just 2,000 years ago. Strong positive selection caused this gene to rise in frequency among some KhoeSan populations. UC Davis anthropologist Brenna Henn and colleagues have shown that a gene for lighter skin spread rapidly among people in southern Africa in the last 2,000 years. This is a "rare example of intense, ongoing adaptation in recent human history and is the first known example of adaptive gene flow at a pigmentation locus in humans," according to the paper published online in the Proceedings of the National Academy of Sciences on Dec. 10. The findings are based on research by multiple scientists. The primary author, Meng Lin, conducted the research as a graduate student at Stony Brook University, working with anthropologist Brenna Henn, now of the University of California, Davis, Genome Center and Department of Anthropology. Lin is now a post-doctoral researcher in genetics at the University of Southern California. In previous work, the researchers looked at pigmentation variation in two KhoeSan populations from South Africa by performing a genome-wide association analysis in about 450 individuals. They followed up on the top associated gene, SLC24A5, by simulating population histories with and without positive selection. The DNA and pigmentation sampling took place in the Northern Cape of South Africa in the southern Kalahari Desert and Richtersveld regions. --- 2017 Razib on Khoisan & Pygmies skin tone & radiation https://www.gnxp.com/WordPress/2017/09/28/selection-for-pigmentation-in-khoisan/ To control for the possibility that genes in this category show an inflated allele frequency differentiation in general, we computed the same statistic for the Mbuti central African rainforest hunter-gatherer group but found no evidence for selection affecting the response to radiation category. … We speculate that the signal for selection in the response to radiation category in the San could be due to exposure to sunlight associated with the life of the Khomani and Juj’hoan North people in the Kalahari Basin, which has become a refuge for hunter-gatherer populations in the last millenia due to encroachment by pastoralist and agriculturalist groups. I’m a bit puzzled here, because the implication seems to be that the San populations are darker than they were in the past. And yet earlier this summer I saw a talk which strongly suggested that there was a selection in modern Bushman populations for the derived variant of SLC24A5, presumably introduced through admixture from East African populations with Eurasian admixture. In comparison to their neighbors the San are quite light-skinned, so it’s a reasonable supposition that they have been subject to natural selection recently. The Hadza, in contrast, seem to have the same complexion as their Bantu neighbors. [/QB][/QUOTE]
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