September 23, 2011
Ancient Humans Settled East Asia In Two Waves, Not One
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An international team of researchers have sequenced the genome of an Aboriginal Australian and determine that early humans settled eastern Asia in two waves rather than just one.
The study has broad implications for understanding how our human ancestors migrated across the globe.
The scientists sequenced the genome of a lock of hair donated to a British anthropologist by an Aboriginal man from the Goldfields region of Western Australia in the early 20th century. The results showed that Aboriginal Australians descend directly from an early human expansion into Asia that took place some 70,000 years ago, at least 24,000 years before the population movements that gave rise to present-day Europeans and Asians, the researchers reported on Wednesday.
The findings also imply that modern day Aboriginal Australians, which were shown to have no genetic input from modern European Australians, are direct descendants of the first humans who arrived in Australia as early as 50,000 years ago.
The history of Aboriginal Australians plays a key role in understanding the dispersal of the first humans to leave Africa. Archaeological evidence establishes modern human presence in Australia by about 50,000 years ago, but the current research re-writes the story of their journey there.
Until now, the most widely accepted theory was that all modern humans derive from a single migration from Africa into Europe, Asia, and Australia. Under that model, the first Australians would have branched off from an Asian population, already separated from the ancestors of Europeans.
However, the current study shows that when ancestral Aboriginal Australians began their private journey, the ancestors of Asians and Europeans had not yet differentiated from each other. Once they did, some 24,000 years after the first Australians had begun their explorations, Asians and remnants of the ancestral Australians intermixed for a period of time.
"Aboriginal Australians descend from the first human explorers. 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,” said Professor Eske Willerslev from the University of Copenhagen, who led the study.
“It was a truly amazing journey that must have demanded exceptional survival skills and bravery."
Professor Jun Wang, another study leader, said the research would open the door to new breakthroughs about ancient human migrations.
"This study will be of great interest to a wide range of researches in Anthropological genetics and Molecular biology. It will also advance our scientific understanding and the construction of human global dispersal patterns,” said Wang, Executive Director of Beijing Genomics Institute.
"With the advanced genome sequencing capability and bioinformatics technologies, we are confident that we will achieve more important breakthroughs in accelerating human genomics research to decipher the conundrum of origin, migration and evolution of our species,” he said.
The research is published September 22 in the journal Science.
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