Scientists have found evidence of what might be a 'new creature' that is neither Neanderthal nor human. X Woman could revise theories about human ancestors and when they left Africa.
A mystery female known as X Woman may add a new chapter to the story of human ancestors leaving Africa to inhabit much of the planet.
Genetic material from a pinkie bone discovered two years ago in Siberia is challenging scientists' understanding of when humans and their evolutionary brethren left Africa, and whether a distinct and previously unknown species might have existed.
Researchers estimate the age of the pinkie bone to be between 30,000 and 48,000 years old. At that time, Neanderthals and anatomically modern humans also lived in that region of Siberia, deep in the Altai Mountains.
But to the researchers' surprise, the bone's genetic signature contained many distinct features compared with those of the remains of Neanderthals or modern humans. Indeed, the team's DNA analysis suggested that the bone came from line of so-called hominins that last shared a common ancestor with Neanderthals and modern humans about 1 million years ago. The team dubbed this potential common ancestor X Woman.
By contrast, Neanderthals and modern humans last shared a common ancestor about 500,000 years ago, anthropologists say – making X Woman about twice as distant from humans on the evolutionary tree as from Neanderthals.
"This was absolutely amazing," says team member Svante Paabo, with the Max Planck Institute for Evolutionary Anthropology in Leipzig. Whoever this was that left "Africa 1 million years ago is some new creature that has not been on our radar screen so far."