A DNA Search for the First Americans Links Amazon Groups to Indigenous Australians
It was a continent believed to have been uninhabited by humans until around 15,000 years ago when the ‘First Americans’ came across a tiny strip of land on the Bering Strait.
However, a recent genetic analysis is threatening to transform theories on who the original native Americans were after discovering some tribes in the Amazon are linked to the Aborigines in Australia.
The results indicate that America may have experienced several waves of migration thousands of years ago, rather than just one that spread from the north across the continent.
Researchers found people belonging to the Suruí, Karitiana and Xavante peoples in the Amazon are more closely related to indigenous populations in Australasia than any other modern group.
They are thought to have been a sea faring people who were able to hop between the islands that extend from Asia to Australia.
The new findings suggest their descendants may have ranged far further and could have crossed the vast ocean expanse between Australia and south America.
However, the researchers say they could have also travelled across ice sheets to the north.
Professor David Reich, a geneticist at Harvard Medical School who led the study, said: ‘It’s incredibly surprising.
‘There’s a strong working model in archaeology and genetics, of which I have been a proponent, that most Native Americans today extend from a single pulse of expansion south of the ice sheets—and that’s wrong.
‘We missed something very important in the original data.
‘About 2 per cent of the ancestry of Amazonians today comes from this Australasian lineage that’s not present in the same way elsewhere in the Americas.’
The researchers, whose work is published in the journal Nature, analysed the DNA from 21 Native American populations in Central and South America.
They also collected and analysed DNA from nine populations in Brazil before comparing it to the genomes of people from 200 non-American populations.
They found the Tupí-speaking Suruí people who first came into contact with the modern world in 1969, the Karitiana tribe, who live in western Amazon, and the Ge-speaking Xavante people in Eastern Brazil, all had genetic links to indigenous Australians.
However, the scientists could not find any other traces in other Native American groups in South, Central or North America.
The researchers say the genetic signals do not match any population known to have contributed to Native American ancestry and the geographic pattern cannot be explained by post-colonial European, African or Polynesian mixture with Native Americans.
Instead they believe the genetic link may be as old as the first human populations to colonise the continent.
It raises the prospect that the Aborigine populations may even have been living in the area before Native Americans arrived.
The researchers say their findings echo suggestions that skeletons of early Native Americans found in Brazil have skulls that have Australasian features.
The researchers have now named the mystery ancestors as Population Y after the after the Tupí word for ancestor, ‘Ypykuéra’.
Dr Pontus Skoglund a geneticist at Harvard Medical School who was part of the team, said: ‘We don’t know the order, the time separation or the geographical patterns.
‘We’ve done a lot of sampling in East Asia and nobody looks like this. It’s an unknown group that doesn’t exist anymore.
‘It suggests there was a greater diversity of the founding populations of the Americas than was previously thought. It was previously completely unknown.’