Geneticists have known for some time that Africans are highly genetically diverse. The claim has even been made that East Africans are more genetically different from West Africans than Europeans are from Asians. That diversity has fit well with the fossil evidence that the human species originated in Africa. It is well established that when a new species, be it plant or animal, arises and spreads, genetic differences accumulate more in geographic regions where the species has been present longer. The more distant populations represent only a small subset of the genetic variation that arose nearer the center of origin.
Now a large international group of researchers has completed the most detailed study of African genetic diversity ever, with enough data they say to pinpoint the southwestern coast of Africa–around the border between today’s Namibia and South Africa—as modern humanity’s homeland.
The Washington Post‘s Joel Achenbach emphasizes the implications for African Americans trying to trace their ancestry to specific populations in the homeland: “African American genealogies are increasingly popular and commercialized, but the authors of the new study cast doubt on how precise such searches can be, given the complexity of the genetic makeup of Africans.”
Nicholas Wade, at the New York Times, focuses on the evolutionary implications, from the center of origin to the point at which migrating Africans departed the continent to populate Asia Minor—a place midway down the Red Sea, which, Wade does not say, implies it must have been a seafaring people who made the crossing.
Tom Avril at the Philadelphia Inquirer gives some space to the researchers’ ordeal in collecting blood from some 2,400 people across 113 ethnic groups in places so remote some of the locals had never seen a white person. Centrifuges had to be run off Land Rover batteries.
Steve Connor of Britain’s Independent led with the researchers’ conclusion that the oldest group in Africa, evolutionarily speaking, are the San, formerly called Bushmen. That’s two of them in the photo. He writes that they are directly descended from the original population of early human ancestors.
Grist: The Science article’s abstract.