Modern humans may have originated from southern Africa, an extensive genetic study has suggested. Data showed that hunter-gatherer populations in the region had the greatest degree of genetic diversity, which is an indicator of longevity. It says that the region was probably the best location for the origin of modern humans, challenging the view that we came from eastern Africa.
     "Africa is inferred to be the continent of origin for all modern human populations," the international team of researchers wrote in the Proceedings of the National Academy of Sciences. "But the details of human prehistory and evolution in Africa remain largely obscure owing to the complex histories of hundreds of distinct populations."
     Co-author Brenna Henn, from Stanford University, California, said the team's study reached two main 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 said. "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," Dr Henn said.
     Dr Henn added: "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. Populations in southern Africa have the highest genetic diversity of any population, as far as we can tell. So this suggests that this might be the best location for (the origins) of modern humans."
     Chris Stringer, a leading palaeontologist based at the Natural History Museum, London, said: "This is a landmark study, with far more extensive data on... hunter gatherer groups than we have ever had before, but I am cautious about localising origins from it. It seems more likely that the surviving hunter-gatherer groups are now localised remnants of populations that formerly ranged across much of sub-Saharan Africa 60,000 years ago." Professor Stringer said that he no longer thought that there was a single "Garden of Eden" where we evolved. Instead, he said, "distinct populations in ancient Africa probably contributed to the genes and behaviours that make up modern humans".

Edited from BBC News (8 March 2011)