Friday, September 23, 2011

Genes map Aborigines' arrival in Australia

A LOCK of hair taken from an unknown young man near Kalgoorlie in the 1920s has provided solid genetic evidence that Aboriginal Australians are descended from the first modern humans to walk out of Africa nearly 75,000 years ago.

Detailed analysis of the Aborigine's genetic blueprint - his genome - by an international team on several continents supports the theory that humans migrated from Africa into eastern Asia in multiple waves, contrary to the theory of a single out-of-Africa migration wave.

The order, or sequence, of the genes in the young man's genome suggests his ancestors were "the first human explorers", leaving Africa before a second group migrated from Africa into eastern Asia, 25,000-38,000 years ago.

The first Aboriginal genome reinforces archeological evidence that people arrived on the Australian continent at least 50,000 years ago and that they share one of the oldest continuous cultures in the world.

Published today in the journal Science, the research was conducted by a Danish, Australian and British team led by evolutionary biologist Eske Willerslev, director of the Centre for Ancient Genetics at the University of Copenhagen.

"Aboriginal Australians descended from the first human explorers," he said.

"While the ancestors of Europeans and Asians were sitting somewhere in Africa or the Middle East, yet to explore their world further, the ancestors of Aboriginal Australians spread rapidly; the first modern humans traversing unknown territory in Asia and finally crossing the sea into Australia.

"It was a truly amazing journey that must have demanded exceptional survival skills and bravery."

The Goldfields Land and Sea Council, which covers the area where the man lived, has endorsed the research, marking a break with past tensions over scientific research. In Kalgoorlie, council chairwoman Dianne Logan said the findings were

"exciting". The project further proved the ancient Aboriginal connection to the land, and Aborigines felt "exonerated in showing the broader community that they are by far the oldest continuous civilisation in the world".

Adelaide-based DNA expert Alan Cooper, head of the Australian Centre for Ancient DNA, who was not part of the research team, agreed the genome strongly supported the idea Aborigines were an early and separate wave of human expansion out of Africa, before the subsequent wave that established Europeans and Asians.

Along with Mike Bunce, head of the Ancient DNA Research Laboratory at Perth's Murdoch University, who co-ordinated the Australian contribution to the program, Professor Willerslev and geneticists in Britain and Denmark concluded that, after the first wave of migration, a second wave of people left Africa 25,000-38,000 years ago.

The team estimated the timing of the first and second migrations using the known rate at which DNA changes, or mutates, over time. Because they had had quality data on 60 per cent of the Aboriginal genome, they had plenty of data to calibrate the "molecular clock".

Then as both waves of immigrants moved into the Middle East and onwards, they swapped genes with archaic people such as the Neanderthals and the Denisovans, and with one another.

A second report this week in the American Journal of Human Genetics by another team - headed by geneticist Mark Stoneking at Germany's Max Planck Institute for Evolutionary Anthropology in Leipzig - details the extent of intermingling by the various groups, and bolsters the Science team's finding of multiple waves of early human movement out of Africa.

Professor Cooper said Professor Stoneking's work showed there was not a single wave of migration out of Africa through to Australia. "There's a whole patchwork of interactions in Asia before the Aboriginal people get to Australia," he said.

The Aboriginal hair sample was collected at a long-gone train station at Golden Ridge, near Kalgoorlie, in 1923, by Cambridge anthropologist and ethnologist Alfred Haddon, who like many anthropologists of the time, believed Aboriginal people were a dying race.

Craig Muller, research manager at the Goldfields Land and Sea Council, said Haddon was in Australia in 1923 to attend a conference in Sydney and Melbourne, but travelled to Western Australia on the Trans-Australia. The train would have stopped for about 40 minutes at Golden Ridge, now just "scrub and gravel". Aboriginal people traded artefacts with passengers along the line, although he "likes to imagine the young man was rather surprised when he was asked to give up some of his hair".

With little provenance other than Haddon's name and the label "Golden Ridge", the sample remained at Cambridge, at the Duckworth Laboratory, devoted to the study of human evolution and variation, until about a year ago when Professor Willerslev learned of its existence.

Initial tests confirmed DNA could be extracted from it. Dr Bunce noted: "That's when Eske got on a plane and came straight over. He's acutely aware that this is a politically charged area."

In particular, the 2005 US Genographic Project aroused much anger among indigenous communities in Australia and the US. The project was denounced as a clone of the Human Genome Diversity Project, which was condemned by the US-based Indigenous Peoples Council on Biocolonialism as an "unconscionable attempt" by genetic scientists "to pirate our DNA for their own purposes".

Dubbed the Vampire Project, the Human Genome Diversity Project was condemned in 1993 by the Central Australian Aboriginal Congress. "The Vampire scientists are planning to take and to own what belongs to indigenous people," it said.

Dr Bunce said "times have moved on" and scientists and indigenous communities had learned how to work together.

Mr Muller said the project had raised several ethical issues for the Goldfields Land and Sea Council, but he was satisfied the sample was obtained ethically, rather than in a way "we would now find distasteful".

In June, Professor Willerslev spoke to the Land and Sea Council to explain his research and gain Aboriginal endorsement.

The council last night said it was excited by the study, which "establishes Aboriginal Australians as the population with the longest association with the land on which they still live today".

"Aboriginal people, in the Goldfields, as elsewhere, always feel secure in their connection to this country, and the research does not alter this fact."

One of the council's directors, Wongatha elder Cyril Barnes, said the genome project was "just a whitefella story" and he would continue to believe in the Wati Kutjara desert creation story, just as other people in Kalgoorlie were Bible-belt creationists.


No comments: