DNA of an indigenous person who lived a thousand years ago in the Northeast helps to explain the population of South America

The DNA of indigenous people who lived in Pernambuco around a thousand years ago may provide important clues about the population of South America before the arrival of Europeans, a new study shows.

Genome analysis of these ancient Northeasterners suggests that they were relatively closely related to other peoples who lived near the South American Atlantic coast, in a wide range that included Minas Gerais and even Uruguay.

On the other hand, their genetic similarities with pre-Columbian inhabitants of the Pacific coast and the Andes were much smaller. This suggests that South America may have originally been populated in two distinct waves, first from the Andean side and later from the Atlantic side, according to the new research.

The work, which has just appeared in the scientific journal Proceedings B, has as its first author the Brazilian André Luiz Campelo dos Santos, a postdoctoral researcher at the Atlantic University of Florida (USA). Researchers from other American institutions and UFPE (Federal University of Pernambuco) also sign the study.

In the work, the team sequenced (roughly, “spelled”) the complete DNA of two individuals found in different archaeological sites in Pernambuco territory. The places, known as Pedra do Tubarão and Alcobaça, are associated with an important style of rock art in the region, the so-called Agreste tradition. In addition, there are no records of the presence of indigenous people in those places in the period after the European invasion, which makes it difficult to associate the remains with present-day native peoples.

In addition to analyzing the genome of the two individuals from Pernambuco, the team compared it with the DNA of other ancient inhabitants of the Americas, which includes skeletons found in Uruguay, Peru, Chile, Panama and the USA.

In the context of prehistoric Brazil, the most crucial comparison involved an inhabitant of the region of Lagoa Santa (MG) who died about 10 thousand years ago. This individual carries in his DNA a small contribution from groups related to present-day Aboriginal Australians and Papua New Guinea natives (collectively known as Australasians).

There is a great deal of discussion about how this component, also found in the genome of current peoples of the Amazon, such as the Suruí and Caritianas, would have reached our continent.

“The entire Pacific Ocean separates Australasia from the Americas, and we still don’t know how these ancestral genomic components appeared in South and Central America without leaving traces in North America”, summarized Campelo do Santos in an official statement about the study.

The comparison showed that the thousand-year-old genomes of the Northeast are relatively close to the ancient inhabitant of Lagoa Santa, but also to the prehistoric natives of Uruguay (about 1,500 years old) and Panama. On the other hand, they are much further away from the DNA of Andean groups.

The meaning behind these kinship lines is still not entirely clear. The safest conclusion, for now, is that the settlement of the eastern region of South America, close to the Atlantic, took place independently of the Andean region. And probably a little later too, as Andean genomes seem to diverge (separate) from the common ancestor of indigenous South Americans at an earlier time.

The researchers also propose that groups such as Lagoa Santa could be ancestors of more northern peoples, with a south-north migration, “up” the Atlantic coast.

Interestingly, although the Australasian-linked DNA component does not appear in the ancient genomes of Pernambuco, the new study detected it in the DNA of the Panamanian individual, which could bolster this hypothesis.

Another possibility is that the ancient indigenous people there had this component in their DNA since the original settlement of the Panamanian territory.

Finally, the work also showed the presence of a small contribution of species of archaic human beings in the DNA of ancient indigenous people, as seen in other parts of the world. In most cases, the main contribution is from Neanderthals, who became extinct 40,000 years ago.

However, in the genomes of Uruguay and Panama, there is a greater genetic contribution from the Denisovans, mysterious archaic humans who lived in Siberia.

“It is phenomenal that Denisovan ancestry has reached South America,” says John Lindo, co-author of the study who works at Emory University (USA). “The interbreeding with them must have taken place a long time ago, perhaps 40,000 years ago.”