Australia's Aborigines were formed from a single group of migrants who left Africa about 55,000 years ago, DNA evidence suggests. Once there the settlers evolved in relative isolation, developing genetic characteristics not found anywhere else and leading to unusual fossil finds that threatened the "out of Africa" hypothesis of human origins. However, research published today confirms that all modern humans stem from a single group of Homo sapiens who emigrated from Africa and spread throughout Eurasia.
A report by a team led by Cambridge and Anglia Ruskin Universities published in the Proceedings of the National Academy of Sciences says Australia's Aboriginal population sprang from the same tiny group of settlers. This group replaced early kinds of humans -such as Neanderthals and Homo erectus, who had already colonised Australia - rather than interbreeding with them.
To trace ancestry back 50,000 years or more the team analysed the mitochondrial DNA and Y chromosome DNA, which is only passed down the male line of Aboriginal Australians and Melanesians from New Guinea. This data was compared with DNA patterns associated with early humans in an international effort with researchers in Oxford, California, and Estonia.
Dr Peter Forster, a geneticist 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."
At the time of the migration, Australia and New Guinea were joined by a land bridge and the region was only separated from the main Eurasian land mass by narrow straits such as Wallace's Line in Indonesia. The land bridge was submerged about 8,000 years ago. Dr Toomas Kivisild, from Cambridge, co-author of the report, said: "The evidence points to relative isolation after the initial arrival, which would mean any significant developments in skeletal form and tool use were not influenced by outside sources."