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Ancient DNA can help bring aboriginal Australian ancestors home

Geneticist David Lambert (right) worked closely with aboriginal Australian leaders on this study, including Michael Young (left), an elder of the Willandra people.

Renee Chapman

By Lizzie Wade

The bones of thousands upon thousands of indigenous people sit in museums across the world. Their descendants want them back, but they must often fight for years to convince scientists the remains belong to their ancestors. And in some cases, information about where the ancestors are from has been lost. Now, a new study from Australia shows ancient DNA can reliably link aboriginal ancestors to their living descendants, opening up the possibility of using genetics to proactively return ancient remains to their communities.

Ancient DNA has already played a role in a handful of repatriation cases in the United States. There, the tribes fought for decades to repatriate specific ancestors and only consented to DNA tests when other lines of evidence were denied. “DNA was a last resort,” says Ripan Malhi, a molecular anthropologist at the University of Illinois in Urbana.

The new study offers a more proactive approach. Geneticists Joanne Wright and David Lambert, both of Griffith University in Nathan, Australia, were working with aboriginal Australian communities on other projects when they got an intriguing request. Tapij Wales, a traditional owner (the term for descendants of people who lived in Australia before Europeans arrived) of the Thanynakwith people in Napranum on Australia’s Cape York Peninsula, asked whether ancient DNA might help bring home aboriginal Australian ancestors from museum collections around the world.

Full ancient genomes from Australia had never been successfully sequenced before, because of the continent’s harsh climate. Plus, colonialism affected the genomes of living aboriginal Australians; many have substantial European ancestry even though they are fully culturally indigenous. Colonial violence, including forced migrations, may have disrupted the genetic links between ancestors and living communities, making them difficult to match up using DNA alone.

Still, Lambert and Wright were game to try. They analyzed samples from 27 aboriginal Australian ancestors up to 1540 years old. All of them had either been previously repatriated or excavated directly from indigenous lands, so the team knew which living communities they belonged to. The researchers managed to sequence mitochondrial genomes, which contain DNA passed down from a person’s mother, from all 27 of them, and nuclear genomes, which contain DNA from both parents, from 10. The next step was to see whether these sequences could match the ancestors with their living descendants.

The team tested the ancient genomes against saliva samples donated to the project by 100 living aboriginal Australians. All 10 of the ancient nuclear genomes showed close genetic relationships with the communities living on the same lands today, proving that they could be a reliable tool for repatriation in Australia, the team reports today in Science Advances. (Wales and 10 other indigenous community members are co-authors of the paper.) But with mitochrondrial DNA, the researchers only got the right answer 60% of the time. That’s not good enough, Lambert says, and it shows that mitochondrial DNA should not be used to guide repatriation. Returning an ancestor to the wrong community “would be extremely hurtful and very damaging,” he says.

Now that he knows the method works, Lambert dreams of putting together a genetic database of living aboriginal Australians and screening the DNA of bones held in museums against it. That could lead to repatriation even in cases where information about the ancestor’s identity has been lost.

Indigenous communities around the world would likely be interested in such a project, says Nanibaa’ Garrison, a bioethicist at the University of Washington in Seattle, and a member of the Navajo Nation. But Keolu Fox, a geneticist at the University of California, San Diego, and a Native Hawaiian, warns that it might not work outside of Australia. Polynesian communities, for example, aren’t as genetically distinct from each other as aboriginal Australian groups are, so ancient DNA wouldn’t be able to match Polynesian ancestors to a specific community or even island. In the worst case scenario, the lack of a DNA match could even be used to deny repatriation claims.

Lambert agrees that future researchers need to collaborate closely with indigenous communities so that they can judge the risks and benefits. But if communities decide to participate, using ancient DNA to bring ancestors home could begin to ease “a huge volume of hurt,” he says. “It is possible. We can do this.”

Source: Science Mag