March 8, 2011 in Nation/World

Humans arose in south Africa, study suggests

Bushmen have greatest genetic diversity
Thomas H. Maugh Ii Los Angeles Times
 

LOS ANGELES – The largest genetic analysis of African populations to date suggests that modern humans originated in southern African about 60,000 years ago, not eastern Africa as is now commonly thought, researchers said Monday.

A team from Stanford University found that the Bushmen hunter-gatherers of the Kalahari Desert who speak one of the Khoisan languages characterized by the presence of clicking consonants have the greatest genetic diversity in their DNA of any people in Africa – and, indeed, the world.

High genetic diversity is generally accepted as a mark of old age of a population, and Africans in general have the greatest genetic diversity of all peoples, indicating that the human race originated on that continent. The new data, reported online Monday in the Proceedings of the National Academy of Sciences, go even further, showing that the greatest diversity of all exists in the hunter-gatherer population and that they must therefore be the most direct descendants of the our oldest ancestors.

The new conclusion was possible because this was the first time it has been possible to compare data from many of the bushman tribes, said geneticist Brenna M. Henn of Stanford, lead author of the paper.

But not everyone agrees with the authors’ reasoning. Though the ancestors of the Khoisan-speaking peoples may indeed have been the first modern humans, that doesn’t necessarily mean that modern humans originated in southern Africa, said anthropologist Henry C. Harpending of the University of Utah.

“These Khoisan were all over southern Africa and east Africa,” Harpending said. Southern Africa “is just the only place they are left. They were wiped out everyplace else. I can’t imagine why that means humans originated in southern Africa.”

Paleoanthropologists generally argue that modern humans originated in eastern Africa because that is where the earliest bones are found. Geneticists, however, argue that that is simply the area that provides the best preservation of fossils.

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