How the first humans arrived in America remains a mystery. The most widely accepted theory is that Ancestral Siberians crossed the Bering Strait during the last Wurm Ice Age (between about 110,000 years ago and about 9700 BC), and colonized the entire continent from north to south. However, recent discoveries point to a possible earlier conquest. Now, the study of Brazil's largest body of genomic data, including DNA from Luzio, the oldest skeleton found in São Paulo, is shedding new light on the origins of these early Americans: Luzio, who lived about 10,000 years ago. A descendant of an ancestral population that settled the Americas at least 16,000 years ago and gave rise to all extant indigenous peoples, including the Tupi, Guarani or Cherokee. The findings have just been published in the journal Nature Ecology & Evolution.
The authors also wanted to explain the sudden disappearance of the oldest coastal communities, which formed the so-called ‘Sambaquis'. Also known as shell dumps and present on other coasts around the world, sambaquis are vast mounds of shells and thorns that were used as a sort of ‘dump' in that they are mainly the hard parts of molluscs. From which they mainly fed these people. themselves, but also bones and even ceramics.
“After the Andean civilizations, the sambaqui makers of the Atlantic coast were the most densely populated human phenomenon in pre-colonial South America,” explains archaeologist André Menezes Strauss of the Museum of Archeology and Ethnography of the University of São Paulo (MAE). -USP) and principal investigator of the study. “They were ‘Kings of the Coast' for thousands and thousands of years. But they suddenly disappeared about 2,000 years ago.”
Reconstructing history through the genome
The authors analyzed the genomes of 34 samples from four different regions of the Brazilian coast. The fossils were at least 10,000 years old and came from Sambaquis and other sites (specifically, Cabecuda, Capelinha, Cubatão, Limao, Jabuticabeira II, Palmeiras Xingu, Pedra do Alexandre and Vau Una). Among the human remains, the remains of the aforementioned Luzio, the oldest skeleton in São Paulo and which were found in the middle of the Capelinha River in the Ribeira de Iguape valley by a group led by MAE professor Levi Figuti. Specialty
Its skull morphology is similar to that of Luzia, the oldest human fossil ever found in Brazil, which is approximately 11,400 years old. The researchers thought it might be a biologically distinct population from today's Native Americans, who settled in what is now Brazil about 14,000 years ago. But they were wrong. “Genetic analysis showed that Luzio was an Amerindian like Tupi, Quechua or Cherokee,” says Strauss. This does not mean that they are all alike, but from a global perspective, they all originated from the same migratory wave that reached the Americas 16,000 years ago. If there was another population here 30,000 years ago, it left no descendants among these groups.”
Same in base, but with difference
Luzio's DNA also revealed that there were two distinct migrations: one inland and one along the coast. Analysis of the genetic material revealed heterogeneous communities with cultural similarities but significant biological differences, particularly between the southeastern and southern coastal communities. “Studies of cranial morphology carried out in the 2000s had already pointed to a subtle difference between these communities, and our genetic analysis confirmed this,” says Strauss. “We found that one reason for this was that these coastal populations were not isolated but were ‘exchanging genes' with inland communities. Over thousands of years, this process may have contributed to regional differences among the Sambaquis.”
Because the Sambuquis on the coast were not the same as those near the interior, rivers, although they were similar, which proves that there were relationships and contacts between them. Now ancient DNA also shows that it was a matter of much more than culture.
Why did the Sambaqui builders disappear?
As for the mysterious disappearance of this coastal civilization, analysis of DNA samples clearly showed that, in contrast to the European Neolithic replacement, in which entire populations were virtually ‘evaporated', this part of the world What happened was a change in practices, with a decrease in the manufacture of sambaquis and the introduction of ceramics. For example, the genetic material found at Galheta IV (Santa Catarina State), the most emblematic site of the time, contains ceramic remains, not shells, and in this respect is similar to Classic Sambquís. That is to say: they changed the shell sambaquis to ceramic ones.
“This information is consistent with a 2014 study that analyzed pottery shards from Sambquís and found that the pots in question were not used for cooking domesticated vegetables but for cooking fish Was. “They used indigenous technology to process foods that were already traditional there,” says Strauss. Other studies have shown that it was climate change, specifically a decrease in sea level in the Atlantic Ocean, that accompanied the collapse of these ancient civilizations.