Shared Roots: Ancient Australian DNA Found in Brazil’s Indigenous People Puzzles Scientists
European colonization caused many groups to relocate from their native places. Researchers for decades have been trying to map out these movements and identify the links between different groups, to map out their story during the new world exploration.
Recently, a study has confirmed that certain tribes of Indigenous people in South America carry ancient Australian DNA with them, ATI reported.
Experts first noted this link in 2015, Science reported. Researchers found out that indigenous people from the Brazilian Amazon were distinctly related to native Australians and Melanesians. The association intrigued researchers as the presence of the genetic signal from Australasian ancestry in so far-flung a population implies that all aspects of the group's interactions in America have not been recorded in history.
In the 2015 study, researchers after analyzing the DNA of more than 200 living and ancient people found Australasian ancestry in two Indigenous Amazonian groups, the Karitiana and Suruí, Science reported. In many of these samples, a signature set of genetic mutations, named the "Y signal" after the Brazilian Tupi word for "ancestor," was found. This caused scientists to speculate whether this Y signal was present in certain ancient South American migrants.
Multiple researchers after the finding assumed that the link between Australasians and the South American indigenous population could be more extensive, ATI reported.
Their assertions were confirmed by tests conducted by experts at the University of São Paulo, ATI reported. The findings have been published in a study that backs up the claim that Australian DNA is even more widespread in Indigenous South Americans than originally thought.
Senior researcher, professor Tábita Hünemeier, and the whole team examined genetic data from 383 modern people in South America, Science reported. The subjects also included dozens of newly genotyped individuals living in the Brazilian Amazon and central plateau.
Scientists identified the Y signal in the Xavánte, who live on the Brazilian plateau in the country's center, and in Peru's Chotuna people, both of whom were outside Amazon, Science reported. This implied that the Australasian DNA was even more widespread than what the 2015 study proposed.
Researchers involved in the study shared, that this finding proves that Australasian individuals did not only interact with Amazonian groups but also with the Pacific coastal population, ATI reported. The Australasian group includes Indigenous Australians and Melanesians, individuals from islands in the Oceania region, and two tribes in Brazil—the Karitiana and the Suruí people.
"Our results showed that the Australasian genetic signal, previously described as exclusive to Amazonian groups, was also identified in the Pacific coastal population," stated Hünemeier, ATI reported.
The researchers used software to understand different scenarios that could have led to the current DNA dispersal, Science reported.
The study authors believe that people who carried the Australasian genes into the New World got it from an ancestral Siberian population, Science reported. According to them, 20,000 years ago, several bands of hardy hunter-gatherers left Siberia and arrived at the now-submerged land of Beringia, which connected Eurasia and Alaska.
After living in Beringia, for 5,000 years, the descendants of these individuals moved into North and South America. Archaeologists have found proof of these descendants setting camp in Monte Verde in southern Chile, through radiocarbon dating.
The researchers further add that the early South American migrants who carried the Y signal, might have taken the coastal route. After that, they must have split off into the central plateau and Amazon sometime between 15,000 and 8000 years ago, as per Hünemeier.
He believes that Y-signal-carrying migrants stuck with the coast as their habitat, and therefore their genetic trace was not found in any North or Central American indigenous groups. Another possibility that he proposes, is that the Y signal-carrying migrants in the north might have died due to colonization.