DNA says new human relative roamed widely in Asia

NEW YORK - Scientists have recovered the DNA code of a human relative recently discovered in Siberia, and it delivered a surprise: This relative roamed far from the cave that holds its only known remains.

By comparing the DNA to that of modern populations, scientists found evidence that these "Denisovans" from more than 30,000 years ago ranged all across Asia. They apparently interbred with the ancestors of people now living in Melanesia, a group of islands northeast of Australia.

There is no sign that Denisovans mingled with the ancestors of people now living in Eurasia, which made the connection between Siberia and distant Melanesia quite a shock.

It is the second report in recent months of using a new tool, genomes of ancient human relatives, to illuminate the evolutionary history of humankind. In May, some of the same scientists reported using the Neanderthal genome to show that Neanderthals interbred with ancestors of today's non-African populations. That might have happened in the Middle East after the ancestors left Africa but before they entered Eurasia, researchers said.

As for the Denisovans, the new work is probably just the start of what can be learned from their genome, said one expert familiar with the research. Eventually, it should give clues to traits like eye and skin color, said Todd Disotell of New York University.

"We're going to be able to piece these people together in the next few years from this genome," he said.

The existence of a new human relative was first revealed just nine months ago from a sampling of DNA recovered from a finger bone discovered in the Denisova Cave in southern Siberia. Researchers proposed the informal name Denisovans for them in Thursday's issue of the journal Nature, where they report the new results.

There is not enough evidence to determine whether Denisovans are a distinct species, the researchers said.

The genome, recovered from the finger bone, showed that Denisovans are more closely related to Neanderthals than to modern humans. That indicates that both they and Neanderthals sprang from a common ancestor on a different branch of the evolutionary family tree than the one leading to modern humans.

Scientists have no idea what Denisovans looked like, said David Reich, a Harvard University researcher and an author of the new paper.

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 which lived in the same area at about the same time as the Denisovans.