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| The field camp at Denisova Cave in southern Siberia, where a new member of the human family tree may have been found |
Scientists have announced they sequenced DNA from the bone fragment of a pinkie finger, possibly from a small child, found in a cave in the Alta Mountains.
The bone found in Denisova Cave was extricated in 2008 from a soil layer carbon-dated to between 30,000 to 48,000 years ago.
Teased from a cellular component called mitochondria, the genome was compared to the code of our extinct cousins the Neanderthals, of homo sapiens, the bonobo and chimpanzee.
The Siberian hominid, the investigation found, had some 400 genetic differences, which makes it a candidate for being a distinct species of homo, as the genus for humans and closely related primates is known.
It, us and the Neanderthals all shared a common ancestor who lived around a million years ago, according to the investigators.
"It's absolutely amazing," co-researcher Svante Paabo said.
"It's some new creature that's not been on our radar screen so far."
The study, published in the weekly journal Nature, was led by Johannes Krause of Germany's Max Planck Institute for Evolutionary Anthropology. Members of the team previously sequenced most of the genome of the Neanderthal.
If their findings are confirmed, much of the early tale of human settlement will have to be revamped.
Until just recently, it was also thought the only human species inhabiting the planet around 40,000 years ago were us and the Neanderthals, who had only a little more time to run before they mysteriously disappeared.
The Altai mountains have yielded evidence that homo sapiens made stone tools there, while Neanderthals lived less than 100km from the Denisova Cave.
If so, what happened?
Did homo sapiens, bigger brained and smarter in communication, wipe out the other species?
Were the other species wiped out by some natural phenomenon or food crisis to which they could not adapt?
Or was there interbreeding, meaning that the extinct species are - in a purely DNA sense - living today through some genes bequeathed to all of us?
"All the theories are still open," University of Manchester specialist Terry Brown said.
"But the interesting thing is that they've just become more complex."