INDIGENOUS Australians and other Melanesian peoples have evolved in part from a hitherto unknown strain of Neanderthal-like Siberians.
German researchers using genetic material extracted from a 40,000-year-old finger bone and tooth discovered in a cave in Russia's Altai Mountains found their owners were part of a race of hominin distinct from both the ancestors of modern humans and the Neanderthals. They named them the Denisovans after the Denisova cave in which the bones were found.
Scientists believe Neanderthals and homo sapiens separated from a common ancestor about 500,000 years ago.
The discovery of the Denisovans, reported in the journal Nature today, showed that Neanderthal-like people were not confined to Europe, said the professor of human evolution at the Australian National University, Colin Groves. "What it now suggests is that the European branch, the Neanderthaloids, were actually a full Eurasian branch, not just European -- and that they had an eastern and a western subdivision," he said.
Furthermore, by comparing their genomes, the German scientists were able to show that homo sapiens inter-bred with the Denisovans while on their way to colonise south Asia and Australia.
"When homo sapiens expanded out of Africa around 100,000 years ago or less, obviously the east Asians incorporated a little gene flow from these Denisovans," Professor Groves said.
While the scientists who conducted the study had no Aboriginal Australian samples, Professor Groves said Melanesians, Papuans and Aboriginal Australians formed a group of related peoples.
"It does seem likely that if there were Aboriginal samples, they too would prove to have some gene flow from the Denisovans," he said.
Professor Groves suggested the remains unearthed at Denisova might be analogous to a skull discovered by farmers in China's Guangdong province in 1958.
The director of the Australian Centre for Ancient DNA at the University of Adelaide, Alan Cooper, said gene-sequencing technology was revolutionising the study of human evolution.
"We've moved from testing existing hypotheses that have been based on traditional science -- fossils and archeology, where we're just testing things that were already known -- to actually making new hypotheses ourselves," Professor Cooper said.
"This thing wasn't even supposed to exist -- there were no remains for it, no knowledge of it -- and yet the genetics is now demonstrating complete chunks of the human tree that were not even known."
Professor Cooper said this and other discoveries showed Asia had a " whole bunch of human history going on that we know nothing about". Asked whether gene-sequencing could redraw the tree of human evolution in the next five years, he replied: "I wouldn't be totally surprised."
