The population of Aboriginal Australians may have been isolated from the rest of the world for about 50,000 years, according to a new study in which scientists have sequenced the Y chromosomes of those individuals.
After they had left Africa approximately 50,000 years ago, modern humans reached Papua New Guinea, Australia, and Tasmania. Archaeological records suggest that about 4,000 to 5,000 years ago, other people came to Australia from India, according to scientists. At that time, the dingoes (Canis lupus dingo) – wild dog found in Australia are generally believed to be descended from semi-domesticated dogs from South or East Asia – also arrived.
However, in the new study published Thursday (Feb. 25) in the journal Current Biology, geneticists said that based on the Y chromosomes – which represent only parental lineages (meaning that they are passed from father to son) – found in indigenous people, there is no evidence that a migration took place four to five thousand years ago.
Dr. Chris Tyler-Smith, one of the study’s lead authors and Head of Human Evolution Team at the Wellcome Trust Sanger Institute (a non-profit, British genomics and genetics research institute), said that the new findings show that Aboriginal Australian Y chromosome originated about fifty thousand years in Australia, and has nothing to do with people from India or South Asia. That means that Australian Aborigines might have been completely separate from the rest of humankind for fifty thousand years, Dr. Tyler-Smith added.
At the time people arrived to Australia, the now separate island nations were actually a continental land mass due to lower sea levels. According to Dr. Tyler-Smith, Sahul – which is the name of the ancient continent – was likely isolated from other people for fifty thousand years.
Scientists said that because the region was located beyond Wallace’s Line (a section of ocean), it was really difficult to access by many species. The first outside influence on Sahul genetics occurred in the 1700s from European invaders.
Tyler-Smith said that Sahul inhabitants are a separate run of human evolution from the one in the Americas and across Eurasia.
Darren Curnoe, an anthropologist at the University of New South Wales in Australia, stated that the idea that Aboriginal Australians and South Asian people are closely related has been debated since the late 1800s. Over the past ten years, geneticists have tried to answer that question.
Dr. Tyler-Smith and his colleagues may conduct further analysis to study the rest of the genome, not only the Y chromosome. That could be a possibility (although quite unlikely) that people did come to Australia, but they did not leave any trace of their Y chromosomes.
According to scientists, the dingoes could have been brought back to Sahul from an expedition to South Asia by some of the Aborigines. The new ways of communicating may have been influenced by environmental changes or resources, some scholars suggested. Previous studies have shown that there might be a link between language and changing climate.
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