Chinese challenge to 'out of Africa' theory

The discovery of an early human fossil in southern China may challenge the commonly held idea that modern humans originated out of Africa.

Jin Changzhu and colleagues of the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, announced to Chinese media last week that they have uncovered a 110,000-year-old putative Homo sapiens jawbone from a cave in southern China's Guangxi province.

The mandible has a protruding chin like that of Homo sapiens, but the thickness of the jaw is indicative of more primitive hominins, suggesting that the fossil could derive from interbreeding.

If confirmed, the finding would lend support to the "multiregional hypothesis". This says that modern humans descend from Homo sapiens coming out of Africa who then interbred with more primitive humans on other continents. In contrast, the prevailing "out of Africa" hypothesis holds that modern humans are the direct descendants of people who spread out of Africa to other continents around 100,000 years ago.

The study will appear in Chinese Science Bulletin later this month.

Out of China?

"[This paper] acts to reject the theory that modern humans are of uniquely African origin and supports the notion that emerging African populations mixed with natives they encountered," says Milford Wolpoff, a proponent of the multiregional hypothesis at the University of Michigan.

Others disagreed. Erik Trinkaus, an anthropologist at Washington University in St Louis, Missouri, questioned whether the find was a true Homo sapiens.

"You need to keep in mind that 'Homo sapiens' for most Chinese scholars is not limited to anatomically modern humans," he says. "For many of them, it is all 'post Homo erectus,' humans."

Chris Stringer of London's Natural History Museum said that it was too early to make far-reaching conclusions. "From the parts preserved, this fossil could just as likely be related to preceding archaic humans, or even to the Neanderthals, who at times seem to have extended their range towards China."

The present analysis of the mandible focused almost exclusively on determining the fossil's age. The researchers said a follow-up study would give a more complete treatment on what exactly the find represents.
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References:

McKenna, Phil. 2009."Chinese challenge to 'out of Africa' theory". New Scientist. Posted: November 3, 2009. Available online: http://www.newscientist.com/article/dn18093