quote:Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5x coverage ancient genome of an Ethiopian male (‘Mota’) who lived approximately 4,500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4,000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6-7% Eurasian ancestry. http://www.sciencemag.org/content/350/6257/149.full
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quote: A paper published online this week in Science (http://scim.ag/MGLlorente) reveals the first prehistoric genome from Africa: that of Mota, a hunter-gatherer man who lived 4500 years ago in the highlands of Ethiopia. Named for the cave that held the remains, the Mota genome “is an impressive feat,” says Hodgson, who was not involved in the work. It “gives our first glimpse into what an African genome looked like prior to many of the recent population movements.” And when compared with the genomes of living Africans, it implies something startling. Africa is usually seen as a source of outward migrations, but the genomes suggest a major migration into Africa by farmers from the Middle East, possibly about 3500 years ago. These farmers' DNA reached deep into the continent, spreading even to groups considered isolated, such as the Khoisan of South Africa and the pygmies of the Congo.
quote:because so many far-flung Africans still carry the farmers' DNA, the study suggests a “huge” migration, Manica says. Farming had already been established in Africa by this time, but the newcomers likely had some advantage that explains why their genes spread. “It must have been lots of people coming in or maybe they had new crops that were very successful,” Manica says.
Population geneticist David Reich of Harvard University is struck by the magnitude of the mixing between Africans and Eurasians. He notes that “a profound migration of farmers moving from Mesopotamia to North Africa has long been speculated.” But, he says, “a western Eurasian migration into every population they study in Africa—into the Mbuti pygmies and the Khoisan? That's surprising and new.”
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