We've all got roots in Africa (if you go back 60,000 years)

Previously it was thought that the unique DNA "fingerprint" of Australia's aborigines contradicted the "out of Africa" hypothesis. But scientists have shown that they have the same ancestors as the rest of us.

This confirms the idea that all modern humans descended from a small band of settlers who left the African plains 55,000 to 60,000 years ago.

Over thousands of years, their numbers grew and they fanned out across the world - replacing older species such as the Neanderthals and Homo Erectus which left Africa much earlier.

Before the new research, geneticists were baffled by the fact that skeletal remains and primitive stone blades found in Australian archaeological sites were strikingly different from those found along the trail taken by the first migrants leaving Africa.

This gave rise to claims that the ancient Aborigines could have inter-bred with more primitive humans such as Homo Erectus, or that they evolved from a much later migration from India.

However, Cambridge University scientists were able to demonstrate that Australia's settlers share common ancestors with the rest of the world by testing DNA samples more extensively than had been possible before.

Dr Peter Forster, who led the research, said: "For the first time, this evidence gives us a genetic link showing that the Australian Aboriginal and New Guinean populations are descended directly from the same specific group of people who emerged from the African migration."

The scientists reported their findings in the journal Proceedings of the National Academy of Sciences.

They wrote that Australian and New Guinean populations share characteristics found nowhere else because they evolved with no genetic input from outsiders once they had settled in Australasia.