There is no such thing as one Indigenous Australian people but rather a continent of extraordinarily genetically-diverse, separate communities with greater genetic variability than between people of European or Asian ancestry. That is the conclusion of two analyses that make up the most detailed survey ever of Indigenous Australian genomes.
The research also pushes back the date of genetic separation between people in Papua New Guinea and those in Australia by around 10,000 years, to approximately 47,000 years ago. This population split occurred more than 35,000 years before the two landmasses separated geographically, but exactly why remains a mystery.
“We have got clear, long-term and stable presence of Indigenous people in Australia for 50,000 years. It’s a very, very long time and, from a human perspective, as close to forever as can be imagined,” says at the Australian National University in Canberra, who is part of one of the research teams and a Yuin man from the south coast of New South Wales. “The study highlights what we have always known – that we are unique and diverse and have lived long, healthy lives for tens of thousands of years. It’s a story of strength and survival.”
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It has long been known that, well before colonisation by Europeans, Australia was made up of at least 200 distinct nations, each speaking its own language. But until now there has been little work done to map the genetic variability of Indigenous Australians between each other and, also, compared with other parts of the world.
Of even greater concern, Indigenous Australians are almost completely absent from the reference datasets that are used to develop genetic therapies, putting them at a major disadvantage for new treatments. , at the Garvan Institute of Medical Research in Sydney, who worked with Brown, says his team’s overarching motivation is to improve diagnosis and treatment of genetic diseases in Indigenous people.
Both of the new studies looked at the genomes of the same 159 individuals from four different Indigenous communities in different parts of Australia.
“We found a lot of unique genetic variation between the different communities,” Deveson says. “Indigenous Australians from different parts of the country were clearly living as distinct nations and their genetic distinctness is striking.”
Both teams also found a globally unprecedented level of genetic similarity between the maternal and paternal lines within the four communities – known as homozygosity. “Within each of the four Indigenous communities that we have worked with there are quite low levels of genetic variability compared to communities elsewhere in the world,” says at the University of Melbourne.
This has the important consequence that Indigenous individuals are more likely to inherit two identical copies of a genetic variant. Depending on the gene, that could be beneficial, harmful, or make no difference at all, he says.
However, the level of variability between the four communities is more extreme than anywhere else in the world other than Africa, says Farlow, with genetic differences in Australia increasing three times faster over comparable distances between human populations than those in Asia and Europe.
Historically, Indigenous Australians have been reluctant to participate in genetic studies conducted by non-Indigenous researchers. For both studies, the teams have ensured that the research has been directed by Indigenous people and the resulting data remains under their control.
This has meant that researchers were able to study the genomes of Tiwi Islanders, who live on two islands in Torres Strait, for the first time. Tiwi Islanders speak a language that is in a completely distinct family compared with others Indigenous Australians, suggesting a separation that has been reflected in the genetic data.
“Tiwi Islanders have the lowest genetic variation within their community and the largest genetic separation between other Indigenous populations in Australia,” says Farlow.
at the Australian National University, who is part of Deveson’s team, says the new work has uncovered genetic variation that had never been described before. “It is enriching the picture and contributing to the knowledge of human diversity,” Patel says, but it is only the beginning. “We know there is even more diversity to be found because there is at least 200 First Nations in Australia.”
Nature
Nature
