Friday, September 23, 2011

For 100 years, the origins of the first walkabout were but a hair’s breadth away

  • 23 Sep 2011
  • The Sydney Morning Herald

A CENTURY-OLD lock of hair from a Western Australian man has been used to piece together the entire genetic code of an Aboriginal person for the first time.

The DNA study shows that the first Australians were also the world’s first human explorers, leaving Africa and the Middle East at least 24,000 years before the ancestors of Europeans and Asians began their travels.
Eske Willerslev, of the University of Copenhagen, said these earliest sojourners would have moved quickly east and south through unknown territory before arriving in Australia about 50,000 years ago.
‘‘It was a truly amazing journey that must have demanded exceptional survival skills and bravery,’’ Professor Willerslev said.
His team’s study established Aborigines as the population outside Africa with the longest association with the land on which they live today, he said.
Almost 100 years ago, a young Aboriginal man from the Goldfields region gave some of his long hair to a British anthropologist, Alfred Haddon, and it ended up in a British museum.
A team member, Michael Bunce, of Murdoch University, said that five years ago it would have been ‘‘laughable’’ to suggest DNA from century-old hair could be used to obtain a human genome sequence.
But hair was proving to be a wonderful source of ancient DNA with which to study the history of human populations.
‘‘The amazing thing is how the technology has moved on so quickly,’’ Dr Bunce, who has also worked with Professor Willerslev on DNA from the 4000-year-old, frozen hair of a Greenland Eskimo, said.
The Aboriginal man’s genome sequence was compared with DNA of populations from Asia, Europe and Africa to show there were multiple waves of migration into Asia from Africa, rather than just one, as some previous studies had suggested.
The researchers estimated the ancestors of Han Chinese left the Middle East after the ancestors of Aborigines set out, about 70,000 years ago. Their findings are published in the journal Science.
In a separate study, another team looked for signs that the ancestors of people alive in south-east Asia today had interbred with Denisovans – recently discovered archaic humans that lived more than 30,000 years ago.
Traces of Denisovan DNA, which was extracted from a pinkie finger bone unearthed in a Siberian cave in 2008, were found in the DNA of Aborigines, New Guineans, and other populations.
This study, published in the American Journal of Human Genetics, also supports the theory of multiple waves of migration into Asia, the researchers said.

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