Thursday, February 12, 2009

Scientists studying the DNA of Neanderthals say they can find no evidence that this ancient species ever interbred with modern humans

But our closest relatives may well have been able to speak as well as us, said Prof Svante Paabo from Germany's Max Planck Institute. The genetics information has been gleaned from fossils found in Croatia. Prof Svante Paabo confirmed that Neanderthals shared the FOXP2 gene associated with speech and language in modern humans. A total of three billion "letters", covering 60% of the Neanderthal genome, have been sequenced by scientists from Max Planck Institute for Evolutionary Anthropology and 454 Life Sciences Corporation, in Branford, Connecticut. The draft genome can give us clues to the genetic regions which make us "uniquely human", Prof Paabo said. Neanderthals lived in Europe and parts of Asia until they became extinct about 30,000 years ago. They were the closest relatives of currently living humans, sharing between 99.5% to 99.9% of our DNA sequence. Pinpointing the differences may reveal the crucial evolutionary changes that that enabled modern humans to leave Africa and rapidly spread around the world, starting around 100,000 years ago. Accordingly, Prof Paabo and his team have focused on genes of special interest in recent human evolution, such as FOXP2, which is involved in speech and language. Humans differ from chimpanzees at two key points in the FOXP2 gene. But the preliminary results suggest that Neanderthals shared these same variations. Since Neanderthals lived side by side with modern humans in Europe for many thousands of years, it has been speculated that we may have inherited some Neanderthal DNA in our genome today, thanks to interbreeding. But Professor Paabo's team have found no evidence for this. They focused on a gene implicated in brain development - microcephalin-1 - which shows significant variation among present day humans. It has been suggested that a particular variant of the gene, found commonly in Europeans, was contributed by Neanderthals. But the Croatian Neanderthal fossils harbored an ancestral form of the microcephalin-1 gene, which today is also found among Africans. Overall, it seems that Neanderthals have contributed, at most, a "very limited" fraction of the variation found in contemporary human populations, said Prof Paabo.

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