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Origin Of Light Skin In Africa
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[QUOTE]Originally posted by the lioness,: [QB] [QUOTE]Originally posted by Doug M: [QB] Khoisan get used a lot in these discussions but one has to remember that all Khoisan aren't light skin and there is no proof that they have been light skin since 80,000 or however far back they split off from East Africans. [/QUOTE] https://www.nature.com/articles/nature08795 Within-Africa analysis separates Bushmen from the divergent western and southern African populations (Fig. 4b), whereas ABT clearly falls within the Southern Bantu cluster. Variable relatedness of the Xhosa to Yoruba may suggest past admixture and/or historical diversity within this broadly defined population24. Within the Bushmen group, we predict that the Ju/’hoansi and HGDP San are essentially the same population. Divergence of KB1 and MD8 may be explained by recent Bantu admixture -- Complete Khoisan and Bantu genomes from southern Africa Stephan C. Schuster, Webb Miller[…]Vanessa M. Hayes Nature volume 463, pages 943–947 (18 February 2010) _________________________________________________ http://www.sciencemag.org/news/2017/10/new-gene-variants-reveal-evolution-human-skin-color [b]New gene variants reveal the evolution of human skin color[/b] By Ann GibbonsOct. 12, 2017 , 2:00 PM “This is really a landmark study of skin color diversity,” says geneticist Greg Barsh of the HudsonAlpha Institute for Biotechnology in Huntsville, Alabama. The team also found variants of two neighboring genes, HERC2 and OCA2, which are associated with light skin, eyes, and hair in Europeans but arose in Africa; these variants are ancient and common in the light-skinned San people. The team proposes that the variants arose in Africa as early as 1 million years ago and spread later to Europeans and Asians. “Many of the gene variants that cause light skin in Europe have origins in Africa,” Tishkoff says. The most dramatic discovery concerned a gene known as MFSD12. Two mutations that decrease expression of this gene were found in high frequencies in people with the darkest skin. These variants arose about a half-million years ago, suggesting that human ancestors before that time may have had moderately dark skin, rather than the deep black hue created today by these mutations. These same two variants are found in Melanesians, Australian Aborigines, and some Indians. These people may have inherited the variants from ancient migrants from Africa who followed a “southern route” out of East Africa, along the southern coast of India to Melanesia and Australia, Tishkoff says. That idea, however, counters three genetic studies that concluded last year that Australians, Melanesians, and Eurasians all descend from a single migration out of Africa. Alternatively, this great migration may have included people carrying variants for both light and dark skin, but the dark variants later were lost in Eurasians. To understand how the MFSD12 mutations help make darker skin, the researchers reduced expression of the gene in cultured cells, mimicking the action of the variants in dark-skinned people. The cells produced more eumelanin, the pigment responsible for black and brown skin, hair, and eyes. The mutations may also change skin color by blocking yellow pigments: When the researchers knocked out MFSD12 in zebrafish and mice, red and yellow pigments were lost, and the mice’s light brown coats turned gray. “This new mechanism for producing intensely dark pigmentation is really the big story,” says Nina Jablonski, an anthropologist at Pennsylvania State University in State College. The study adds to established research undercutting old notions of race. You can’t use skin color to classify humans, any more than you can use other complex traits like height, Tishkoff says. “There is so much diversity in Africans that there is no such thing as an African race.” [IMG]https://bglh-marketplace.com/wp-content/uploads/2015/08/CL0kirkWUAA7wcu.jpg[/IMG] [/QB][/QUOTE]
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