BEIJING: The finding of a 40,000-year-old human skeleton in China virtually questions the popular theory of "out-of-Africa" dispersal of modern humans.
Researchers at Washington University in St Louis and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, who have been studying the skeleton, feel the "out-of-Africa" theory may not be as simple as was previously thought.
Erik Trinkaus, professor of anthropology at Washington University in St Louis, and Hong Shang from the Institute of Vertebrate Paleontology and Paleoanthropology and their colleagues, after a detailed study of the skeleton, recovered from the Tianyuan cave in Zhoukoudian near Beijing in 2003, found that it has all the characteristics of a modern human, but it does have a few archaic characteristics too, particularly in the teeth and hand bones.
Based on this finding, the researchers say it is hard to believe the accepted theory of an eastward spread of modern humans from Africa. They point out that finding of slightly younger skeletons in eastern Eurasia with similar characteristics support their view.
Most probably, the gene flow could have happened from the west and south, the researchers contend.
The skeleton dates to 42,000 to 38,500 years ago and it is one of the oldest fossils of the modern man in eastern Eurasia.
The skeleton offers additional data on several aspects of its biology and a detailed study will be useful in reconstructing the transition from archaic to modern humans in eastern Eurasia, the researchers say.
Trinkaus and Shang say the discovery promises to provide relevant paleontological data for the understanding of the emergence of modern humans in eastern Asia.
Details of the study have been published in online issue of the journal Proceedings of the National Academy of Sciences.
The "out-of-Africa" theory claims Homo sapiens evolved in East Africa and then spread out across the globe about 70,000 years ago, replacing earlier human species like Neanderthals. Scientists believe there had been very little or no interbreeding among the two species.
The skeleton from the Tianyuan cave have bones and large front teeth that are characteristic of earlier human species. Trinkaus and Shang feel the easiest way to explain this is that interbreeding between the early modern humans from Africa and the archaic populations they encountered in Europe and Asia had indeed happened.
The study of the bones also revealed that the ancient individual could be in late 40s or early 50, his or her sex could not be ascertained because of lack of pelvic bones, the individual had several signs of disease, with several lesions, or growths, found on the leg bones, he or she had led an active life and had been wearing shoes as indicated by a toe bone recovered.
