Saturday, December 25, 2010

Newfound human ancestor roamed Asia

NPR: DNA taken from a pinkie bone at least 30,000 years old is hinting at the existence of a previously unknown population of ancient humans... The pinkie bone in question was unearthed in 2008 from what's called the Denisova Cave. 'The Denisova Cave is in southern Siberia in the Altai Mountains in central Asia,' says David Reich, a geneticist at Harvard Medical School in Boston. 'This bone is the bone of a 6- to 7-year old girl.'

Reich says there were several remarkable things about the group of people this girl is from, a group he and his colleagues call Denisovans. 'On the one hand it's a sister group to Neanderthals, which means that it's more closely related to Neanderthals on average than it is to modern humans.'... As he reports in the journal Nature, the other remarkable finding was that the Denisovans' genome was more closely related to humans currently living in New Guinea than it was to genomes of people in Europe or Asia...

New Human Relative: DNA Says 'Denisovans' Roamed Widely in Asia
AP: Apart from the genome, the researchers reported finding a Denisovan upper molar in the cave. Its large size and features differ from teeth of Neanderthals or early modern humans, both of whom lived in the same area at about the same time as the Denisovans...

Of people now living in Melanesia, about 5 percent of their DNA can be traced to Denisovans, a sign of ancient inbreeding... that suggests Denisovans once ranged widely across Asia... Somehow, they or their ancestors had to encounter anatomically modern humans who started leaving Africa some 55,000 years ago and reached New Guinea by some 45,000 years ago.

Der Spiegel: Some 300,000 years ago [the Denisovans] split off from the branch which eventually developed into the Neanderthals. Whereas the Neanderthals spread westward into ice-age Europe, the Denisovans moved east...

The scientists compared DNA from the Denisova cave with that of modern man... Clear indications of intermingling were only found among the inhabitants of Papua New Guinea. The two types of hominids, researchers believe, must have encountered each other somewhere in Southeast Asia some 30,000 years ago. The two groups must have interbred, perhaps not as a matter of course, but periodically. Later, the modern humans and their genetic dowry moved further south, whence today's Melanesians developed.
Image: Denisovan molar; source here.