Ancient DNA study casts light on origin of ancestral Brazilians
Brazilian scientists have mastered all the stages of the technique for extracting and sequencing ancient DNA in biological material from archaeological excavations dating back thousands of years.
The process for sequencing the material, normally found in bone fragments, was developed by Swedish biologist Svante Pääbo, winner of the 2022 Nobel Prize in Physiology or Medicine for his discoveries regarding the genome of extinct hominids and human evolution.
As it happens, it was at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, where Pääbo works as director of genetics, that Brazilian researcher Tiago Ferraz earned his doctorate before bringing his knowledge of the technique to the University of São Paulo (USP).
Still in Germany, Ferraz was responsible for the ancient DNA sequencing that resulted in the article Genomic History of Coastal Societies from Eastern South America, published in the journal Nature Ecology & Evolution.
Ferraz’s work ranged from the extraction of the bone powder—where the DNA is retained—to data analysis and the interpretation of results.
The study—which had André Menezes Strauss, an archaeologist from USP’s Museum of Archaeology and Ethnology (MAE) as senior researcher and Tiago Ferraz as first author—was also supported by experts from the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen, Germany.
“This work has a vital institutional role. It is the first time a Brazilian-led team, alongside so many institutions, has managed to publish a high-impact article in the field of archaeogenetics,” Strauss noted.
The sambaquieiros
The study was based on the extraction of the genome of 34 samples up to 10 thousand years old from four different regions on the east coast of Brazil. Among the material is Luzio, São Paulo’s oldest skeleton, which is around 13 thousand years old.
According to André Strauss, the technique proved instrumental in unraveling one of the enigmas of Brazilian archaeology: Did these ancient coastal populations on the Brazilian coast—called sambaquieiros, the ancestors of today’s indigenous people—stem from just one biological group or several distinct peoples?
“Genetic analysis showed that this hypothesis [their origin stemming from distinct peoples] was wrong. The genetic data show they are descended from the same ancestral population, which occupied [what is now Brazil] 16 thousand years ago, just like any other indigenous group in Brazil or the Americas,” Strauss pointed out.
One of the theories, now challenged by archaeogenetics, argued that the continent had been colonized by two waves of Homo sapiens from Asia. The first migratory wave is said to have occurred 14 thousand years ago, with individuals with a non-mongoloid morphology—similar to that of present-day Australians and Africans, but who left no descendants here. The second wave is believed to have arrived 12 thousand years ago, and its members reportedly had the physical type characteristic of Asians, from which modern indigenous people are thought to derive.
The result of the recent ancient DNA study shows, however, that there were not two migrations. “What we do have is intracontinental migration: people coming here from the Andes, from North America, from South America—but these are local processes. These great migrations, the genetic data, contrary to what had been imagined until now, point toward a single migration from Asia,” Strauss declared.
USP laboratory
Trained for two years at Germany’s Max Planck Institute, globally renowned for ancient DNA research, Ferraz now hopes that USP’s Laboratory of Archaeology and Environmental and Evolutionary Anthropology will be fully operational by the end of 2023. The facility is the country’s first archaeogenetics laboratory and was built in collaboration with the German institute.
The researcher says that once the laboratory is fully functional, with “a solid system for processing samples and decontaminating material,” the sequencing of ancient DNA may take place in Brazil without the need for foreign facilities. “We’re adapting the space. We’ve been dealing with various technical and bureaucratic issues,” he said. “We’re putting the finishing touches to it so we can finally open the space and actually work in it, with a more intense work routine.”
The first objective, he went on to say, will be to train local researchers to generate archaeogenetic data on site. “Now that we’ve brought the technique to Brazil, we’re going to implement it here, do it locally, sequence the individuals, sequence the ancient DNA here in Brazil, and train people to work with it.”
