Notícia

Tech2 (Reino Unido)

The new face of south american people

Publicado em 11 novembro 2018

The history of the peoples of America has just been reinterpreted. The largest and most comprehensive study ever conducted on the basis of fossil DNA extracted from ancient human remains found on the continent has confirmed the existence of a single ancestral population for all Amerindian ethnic groups, past and present.

More than 17,000 years ago, this original contingent crossed the Bering Strait from Siberia to Alaska and began to populate the New World. Fossil DNA shows an affinity between this migratory flow and the populations in Siberia and North China. In contrast to traditional theory, it had no connection with Africa or Australasia.

The new study also reveals that after they had established themselves in North America, the descendants of this ancestral migratory flow had diversified into two generations 16,000 years ago.

The members of a race crossed the Isthmus of Panama and populated South America in three different consecutive waves.

The first wave took place between 15,000 and 11,000 years ago. The second took place at most 9,000 years ago. There are fossil DNA records from both migrations throughout South America. The third wave is much more recent, but its influence is limited since it occurred 4,200 years ago. The members settled in the central Andes.

An article about the study has just been published in the magazine Cell a group of 72 researchers from eight countries, affiliated with the University of São Paulo (USP) in Brazil, Harvard University in the United States, and Max Planck Institute for the Science of Human History in Germany, among others.

According to the findings of the researchers, the descent that made the north-south journey between 16,000 and 15,000 years ago belonged to the Clovis culture, named after a group of archaeological sites excavated in the western part of the US, dating back to 13,500-11,000 years. ago.

The Clovis culture was so named when in the thirties flint spearheads were found during an excavation in Clovis, New Mexico. Clovis sites have been identified throughout the US and in Mexico and Central America. In North America, the Clovis people hunted Pleistocene megafauna & # 39; s such as gigantic laziness and mammoth. With the deterioration of the megafauna and its extinction 11,000 years ago, the Clovis culture eventually disappeared. Long before, groups of hunter-gatherers had traveled to the south to explore new hunting grounds. They eventually settled in Central America, as evidenced by 9,400 years old human fossil DNA found in Belize and analyzed in the new study.

Later, perhaps during the pursuit of herds of mastodons, Clovis hunter-gatherers crossed the Isthmus of Panama and spread to South America, as evidenced by genetic data from cemeteries in Brazil and Chile that have now been unveiled. This genetic evidence confirms well-known archaeological finds such as the Monte Verde site in southern Chile, where people slaughtered people 14,800 years ago.

Among the many known Clovis sites is the only cemetery associated with Clovis tools in Montana, where the remains of a baby boy (Anzick-1) were found and date back to 12,600 years ago. DNA extracted from these bones has links with DNA from skeletons of people living between 10,000 and 9,000 years ago in caves at Lagoa Santa, Minas Gerais, Brazil. In other words, the Lagoa Santa people were a partial descendant of Clovis migrants from North America.

"From the genetic point of view, the Lagoa Santa people are descendants of the first Amerindians," said archaeologist André Menezes Strauss, who coordinated the Brazilian part of the study. Strauss is attached to the Museum of Archeology and Ethnology of the University of São Paulo (MAE-USP).

"Surprisingly, the members of this first generation of South Americans have not left any identifiable descendants with the modern-day Indians," he said. "About 9,000 years ago their DNA disappeared completely from the fossil samples and was replaced by DNA from the first wave of migration, prior to the Clovis culture.All living Amerindians are descendants of this first wave.We do not yet know why the genetic population of the Lagoa Santa disappeared people. "

A possible reason for the disappearance of DNA from the second migration is that it was diluted in the DNA of the Amerindians who descended from the first wave and can not be identified by existing methods of genetic analysis.

According to Tábita Hünemeier, a geneticist at the University of São Paulo's Bioscience Institute (IB-USP) who participated in the study, "one of the most important results of the research was the identification of Luzia's people as genetically related to the Clovis culture, the idea of ​​two biological components and the possibility that two migrations to America were dismantled, one with African characteristics and the other with Asian characteristics.

"The people of Luzia must be the result of a migration wave from Beringia," she said, referring to the now under water Bering land bridge that Siberia added to Alaska during the glaciers, when the sea level was lower.

"The molecular data suggest population substitution in South America since 9,000 years ago." Luzia's people disappeared and were replaced today by the indigenous Indians, although both had a common origin in Beringia, "Hünemeier said.

Brazilian contribution

The contribution of the Brazilian researchers to the research was fundamental. Of the 49 people from which the fossil DNA was made, seven skeletons emerged between 10,100 and 9,100 years ago from Lapa do Santo, a refuge in the Lagoa Santa.

The seven skeletons, along with dozens of others, were found and excavated in successive archaeological campaigns on the site, initially led by Walter Alves Neves, a physical anthropologist at IB-USP, and since 2011 by Strauss. The archaeological campaigns led by Neves between 2002 and 2008 were funded by São Paulo Research Foundation – FAPESP.

All in all, the new fossil DNA study of 49 people was found at 15 archaeological sites in Argentina (two locations, 11 individuals dated between 8,900 and 6,600 years ago), Belize (one site, three people dated between 9,400 and 7,300 years ago), Brazil (four locations, 15 people dated between 10,100 and 1,000 years ago), Chile (three locations, five people dated between 11,100 and 540 years ago) and Peru (seven locations, 15 people dated between 10,100 and 730 years ago).

The Brazilian skeletons originate from the archaeological sites of Lapa do Santo (seven individuals date about 9,600 years ago), Jabuticabeira II in the state of Santa Catarina (a sambaqui or shell center with five individuals dating back 2,000 years ago), as well as two river in the middle of the Ribeira Valley, São Paulo: Laranjal (two people date from about 6700 years ago), and Moraes (a person dated about 5800 years ago).

Paulo Antônio Dantas de Blasis, an archaeologist associated with MAE-USP, led the excavation at Jabuticabeira II, which was also supported by FAPESP through a thematic project.

The excavations at the middle site of the river in the state of São Paulo were led by Levy Figuti, also archaeologist at MAE-USP, and were also supported by FAPESP.

"The Moraes skeleton (5800 years old) and the Laranjal skeleton (6700 years old) are among the oldest in the south and southeast of Brazil," said Figuti. "These locations are strategically unique because they are located between the highlands of the Atlantic plateau and the coastal plain, which contributes significantly to our understanding of how the southeast of Brazil was populated."

These skeletons were found between 2000 and 2005. From the beginning they presented a complex mix of cultural features along the coast and inland, and the results of their analysis generally varied, except in the case of a skeleton diagnosed as Paleoindian (analysis of his DNA is not yet complete ).

"The study that has just been published represents a major step forward in archaeological research, exponentially increasing the number of knowledge we had until a few years ago about the archaeogenetics of the populations in North and South America," said Figuti.

Hünemeier has also recently made an important contribution to the reconstruction of human history in South America with the help of paleogenomics.

Amerindian genetics

Not all human remains found at some of the oldest archaeological sites in Central and South America were genetic descendants of the Clovis culture. The residents of different locations did not have Clovis-associated DNA.

"This shows that in addition to the genetic contribution, the second wave of migration to South America, which was Clovis-associated, could also entail technological principles that would be expressed in the famous fishtail points found in many parts of South America. avoid "Strauss said.

How many human migrations from Asia to America came at the end of the ice age, more than 16,000 years ago, was unknown until now. The traditional theory, formulated in the 1980s by Neves and other researchers, was that the first wave had African characteristics or characteristics similar to those of the Australian Aborigines.

The well-known forensic facial reconstruction of Luzia was carried out in accordance with this theory. Luzia is the name given to the fossil skull of a woman who lived 12,500 years ago in the Lagoa Santa area and who sometimes has the first Brazilian & # 39; is called.

The bust of Luzia with African characteristics was built on the basis of the morphology of the skull by the British anatomical artist Richard Neave in the nineties.

"However, skull form is not a reliable marker of ancestral or geographical origin. Genetics is the best basis for this type of inference," explains Strauss.

"The genetic results of the new research show categorically that there was no significant link between the Lagoa Santa people and groups from Africa or Australia, so the hypothesis that Luzia's people originated from a migration wave prior to the ancestors of the contemporary Indians has been refuted, on the contrary, the DNA shows that the people of Luzia were completely Amerindian. "

A new bust has replaced Luzia in the Brazilian scientific pantheon. Caroline Wilkinson, a forensic anthropologist at Liverpool John Moores University in the UK and a disciple of Neave, has made a face reconstruction of one of the persons excavated in Lapa do Santo. The reconstruction was based on a redesigned digital model of the skull.

"Accustomed to the traditional facial reconstruction of Luzia with strong African characteristics, this new facial reconstruction reflects the physiognomy of the first inhabitants of Brazil much more accurately, with the generalized and unclear features that made up the great Amerindian diversity over thousands of years," said Strauss.

The study published in Cell, he added, also presents the first genetic data about the Brazilian sambaquis on the coast.

"These monumental shell mounds were built around 2,000 years ago by densely populated societies on the coast of Brazil, and fossil DNA analysis of shell grave burials in Santa Catarina and São Paulo shows that they are genetically genetically related to the Amerindians who live in the south today. from Brazil, especially the Kaingang groups, "he said.

According to Strauss, DNA extraction from fossils is technically very challenging, especially if the material was found in a location with a tropical climate. For almost two decades, extreme fragmentation and considerable contamination prevented various research groups from successfully extracting genetic material from the bones found at Lagoa Santa.

This has now been done thanks to the methodological progress developed by the Max Planck Institute. As Strauss enthusiastically explained, there is much more to discover.

"The construction of the first archaeological laboratory in Brazil will start as planned in 2019, thanks to a partnership between the Museum of Archeology and Ethnology at the University of São Paulo (MAE) and the Bioscience Institute (IB) with funding from FAPESP. is, it will give new impetus to research on the populations in South America and Brazil, "said Strauss.

"To some extent, this study not only changes what we know about how the region was populated, but also significantly changes how we study human skeletal remains," Figuti said.

Human remains were first found in Lagoa Santa in 1844, when the Danish naturalist Peter Wilhelm Lund (1801-1880) discovered about 30 skeletons deep in a flooded cave. Almost all these fossils are now in the Natural History Museum of Denmark in Copenhagen. A single skull has remained in Brazil. It was donated by Lund to the Brazilian Institute for History and Geography in Rio de Janeiro.

Colonization by leaps and bounds

On the same day as the Cell article was published (8 November 2018), a paper in the journal Science also reported new findings on fossil DNA from the first migrants to North and South America. André Strauss is one of the authors.

Of the 15 old skeletons made from genetic material, five belong to the Lund collection in Copenhagen. They date from 10,400 to 9,800 years ago. They are the oldest in the sample, in addition to a person from Nevada who is estimated to be 10,700 years old.

The sample consisted of fossilized human remains from Alaska, Canada, Brazil, Chile and Argentina. The results of his molecular analysis suggested that the populations of the Americas by the first human groups from Alaska were not only brought about by gradual occupation of territory together with population growth.

According to the researchers responsible for the study, the molecular data suggest that the first people invading Alaska or neighboring Yukon have been split into two groups. This happened between 17,500 and 14,600 years ago. One group colonized North and Central America, the other South America.

The population of the Americas followed with leaps and bounds, as small groups of hunter-gatherers traveled far and wide to settle in new areas until they reached Tierra del Fuego in a movement lasting one or two millennia at most.

Among the 15 individuals whose DNA was analyzed, three of the Lagoa Santa were found to have five genetic material from Australasia, as suggested by the theory that Neves proposed for the occupation of South America. The researchers are not able to explain the origin of this Australasian DNA or how it ended up in just a few of the Lagoa Santa people.

"The fact that the genomic signature of Australasia has been present in Brazil for 10 400 years, but is absent in all genomes that have been tested so far, which are so old or older, and further north, is a challenge given the presence in Lagoa Santa, "they said.

Other fossils collected in the twentieth century are the Luzia skull, which was found in the seventies. Almost 100 skulls that Neves and Strauss have excavated in the past 15 years are now stored at USP. A similar number of fossils is held at the Papal Catholic University of Minas Gerais (PUC-MG).

But the vast majority of these osteological and archaeological treasures, which belonged to perhaps more than 100 people, were deposited at the National Museum in Rio de Janeiro and were probably destroyed by the fire that rages through this historic building on September 2, 2018.

The Luzia skull was shown in the National Museum next to Neave's facial reconstruction. Scientists feared that it had been lost by fire, but fortunately it was one of the first objects recovered from the ruins. It had fallen apart but survived. The fire destroyed the original face reconstruction (of which there are several copies).