By analysing ancient DNA, a team of international researchers uncover previously unknown genetic exchanges between North and South America.
By analysing the first high-quality ancient DNA from Central and South America – from 49 individuals, some dating back as far as 11,000 years – the researchers revealed an early population turnover. The data, published in Cell, showed genetic similarities between individuals associated with the Clovis culture (the first clear evidence of human activity in North America) and the oldest Central and South Americans. This rules out the possibility that a single population founded South America. The team found evidence that the Clovis culture also had an impact further down into Central and South America, most likely related to agricultural expansion.
For Pontus, these recent findings are particularly exciting as they relate closely to his 2015 paper, published in Nature, where he revealed a genetic link between Amazonian Native Americans and indigenous Australasians. He said: “I’m very excited to see this published as it addresses an enduring mystery of the peopling of the Americas. How, some 15,000 years ago, people overcame tough environmental conditions to settle there is a fascinating event in prehistory.”
Interestingly, the present population of South America, as well as younger individuals from the region dating back 1,000 years, do not share the Clovis-associated heritage present in the oldest individuals. Instead, there is genetic continuity between ancient South American individuals and present-day populations. This suggests there was a major population turnover that began at least 9,000 years ago, followed by a long period of stability until today. In comparison, other world regions, such as western Eurasia and Africa, have seen widespread population replacements.
This study marks a significant development in the continuing work to understand the peopling of the Americas. Previously, the only available data of this age could be found in Montana, North America. From South America, genomes of suitable analysis quality were less than 1,000 years old. For this study, the researchers worked closely with government agencies and indigenous communities to get permits to analyse ancient human remains dating between 9,000 to 11,000 years.
However, for Pontus and other international researchers, these findings represent just ‘the tip of the iceberg’ of what is yet to be uncovered. “The Americas have a rich pre-history, but there are several regions without ancient DNA data,” said Pontus. In future, the researchers hope to obtain larger sample sizes and regionally-focused data in order to draw a more detailed picture of how the human diversity of the Americas came to be the way it is today.
At the Crick, Pontus’ lab is continuing work in this area: “The aim is to gain a better understanding of the diversity of the first people in the Americas and how they adapted to new lifestyles and environments. This will also contribute to furthering precision medicine for people of Native American and Latino ancestry around the world”.