The creature, dubbed “X-woman” by scientists, may have been one of at least three kinds of human alive at the time.
What it looked like is unknown, but scientists believe it was closer to modern humans than the stout and muscular Neanderthals.
Surviving in a harsh ice-age period, “X-woman” would have hunted animals and clothed itself with furs and skins against the cold.
Experts already know that early Homo sapiens and Neanderthals co-existed in northern Asia and Europe for 15,000 years. The new evidence, based on DNA from a piece of finger bone found in a cave, indicates that a third species might also have been present.
Scientists do not rule out the possibility other ancient humans may have evolved.
The new find is unusual because it is based entirely on molecular evidence from DNA. It suggests the appearance of a completely new lineage of humans that emigrated out of Africa one million years ago.
Scientists found the finger bone in Denisova Cave in the Altai Mountains of southern Siberia. It belonged to a child, aged around six, and came from a rock layer dated to between 30,000 and 48,000 years ago. With no other clues, the scientists, led by Dr Johannes Krause from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, analysed the bone’s preserved mitochondrial DNA (mtDNA). This is DNA housed in the rod-like power plants, called mitochondria, that generate energy in the cell. Unlike DNA from the cell nucleus, mtDNA is only inherited from mothers.
The researchers were in for a surprise. The genetic material was nothing like that of either early modern humans or Neanderthals.
Dr Svante Paabo, also from the Max Planck Institute, was in the US when he was told of the results in a phone call from Dr Krause. He said: “It was absolutely amazing. At first I didn’t believe him. I thought he was pulling my leg.
“Whoever carried this mitochondrial DNA was some new creature that had not been on our radar.”
They believe the creature had an ancestor that arrived from Africa around a million years ago and pre-dated modern humans and Neanderthals.