'Woman X' a previously unknown human ancestor?

A previously unknown kind of human group vanished from the world so completely that it has left behind the merest wisp of evidence that it ever existed — a single bone from the little finger of a child, buried in a cave in the Altai mountains of southern Siberia.

Researchers extracted DNA from the bone and reported on Wednesday that it differed conspicuously from that of both modern humans and of Neanderthals, the archaic human species that inhabited Europe until the arrival of modern humans on the continent some 44,000 years ago.

The child who carried the DNA lineage (nicknamed ‘Woman X’) was probably 5 to 7 years old, but it is not yet known if it was a boy or a girl. The finger bone was excavated by Russian archaeologists in 2008 from a place known as the Denisova cave.