March 8, 2011

Study Traces Human Origins To Southern Africa

Modern man may have evolved from the bushmen of Southern Africa, not from the eastern part of the continent as many experts suggest, claims a new study published Monday in the journal Proceedings of the National Academy of Sciences (PNAS).

A team of experts from Stanford University, Santa Clara University, the University of California, Brown University, Cornell University, the Yale University School of Medicine, the Institute of Evolutionary Biology at the Universitat Pompeu Fabra in Spain, and 23andMe, a privately-owned genetic testing and biotechnology firm, studied DNA samples from 27 populations currently living in the continent of Africa.

Stanford's Dr. Brenna Henn, co-author of the study, told BBC News Science and Environment Reporter Mark Kinver that their research let them to a pair of conclusions.

"One is that there is an enormous amount of diversity in African hunter-gatherer populations, even more diversity than there is in agriculturalist populations," she told BBC News. "These hunter/gatherer groups are highly structured and are fairly isolated from one another and probably retain a great deal of different genetic variations--we found this very exciting."

"The other main conclusion was that we looked at patterns of genetic diversity among 27 (present-day) African populations, and we saw a decline of diversity that really starts in southern Africa and progresses as you move to northern Africa," Dr. Henn added. "Populations in southern Africa have the highest genetic diversity of any population, as far as we can tell."

That genetic diversity, Henn and her colleagues say, suggests that they may well be the forefathers of the first true Homo sapiens. Past fossil records have led scientists to surmise that humans originated in East Africa between 60,000 and 150,000 years ago before migrating to other lands.

Natural History Museum, London Paleontologist Chris Stringer, who was not involved in the research, called it "a landmark study, with far more extensive data on... hunter gatherer groups than we have ever had before."

However, as Stringer also told Kinver, "but I am cautious about localizing origins from it," since rock paintings attributed to the Bushmen suggest that they were at one time far more widespread than they are today,  and that he believed that "distinct populations in ancient Africa probably contributed to the genes and behaviors that make up modern humans".


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