The new face of the South American people – ScienceDaily

More than 17,000 years ago, this contingent of origin crossed the Bering Strait from Siberia to Alaska and began populating the New World. Fossil DNA shows an affinity between this migratory current and the populations of Siberia and northern China. Contrary to traditional theory, it had no connection with Africa or Australasia.

The new study also reveals that once settled in North America, the descendants of this ancestral migratory flow diversified into two lineages about 16,000 years ago.

Members of one lineage crossed the Isthmus of Panama and populated South America in three separate consecutive waves.

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

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

According to the researchers' findings, the lineage that made the north-south journey between 16,000 and 15,000 years ago belongs to the Clovis culture, named in reference to a group of archaeological sites unearthed in the west from the United States and dating from 13,500 to 11,000 years ago.

The Clovis culture was so named when flint spearheads were found in the 1930s during a search in Clovis, New Mexico. Clovis sites have been identified in the United States, Mexico and Central America. In North America, the Clovis hunted Pleistocene megafaunes, such as giant sloth and mammoth. With the decline of the megafauna and its extinction 11,000 years ago, the Clovis culture finally disappeared. Long before that, however, groups of hunter-gatherers had gone to the south to explore new hunting grounds. They ended up settling in Central America, as evidenced by the 9,400-year-old human fossil DNA discovered in Belize and badyzed in the new study.

Later, perhaps while pursuing herds of mastodons, Clovis hunter-gatherers crossed the Isthmus of Panama and spread to South America, as evidenced by the genetic records of burial sites in Brazil and in Chile. This genetic evidence corroborates well-known archaeological discoveries such as the Monte Verde site in southern Chile, where humans slaughtered behemoths 14,800 years ago.

Of the many known Clovis sites, the only burial site badociated with Clovis tools is found in Montana, where the remains of a baby boy (Anzick-1) were found and dated 12,600 years ago . The DNA extracted from these bones is linked to the skeleton DNA of people who lived 10,000 to 9,000 years ago in caves located near Lagoa Santa, in the state of Minas Gerais. , in Brazil. In other words, the Lagoa Santa were partial descendants of Clovis migrants from North America.

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

"Surprisingly, the members of this first South American lineage have not left any identifiable descendants among the Native Americans of today," he said. "Some 9000 years ago, their DNA completely disappears from fossil samples and is replaced by the first migration wave, prior to Clovis culture.All living Amerindians are the descendants of this first wave.We do not know still why the genetic stock of the people of Lagoa Santa has disappeared. "

One of the possible reasons for the disappearance of DNA from the second migration is that it has been diluted in the DNA of Native Americans, descendants of the first wave, and can only be identified by the methods of D & D. Existing genetic badysis.

According to Tábita Hünemeier, a geneticist from the Institute of Bioscience of the University of São Paulo (IB-USP) who participated in the research, "one of the main results of the study was the identification of the inhabitants of Luzia as genetically related to the Clovis culture, which destroys the idea of ​​two biological components and the possibility that there are two migrations to the Americas, one with African traits and the 'other with Asian traits.'

"The people of Luzia must come from a migratory wave originating in Beringia," she said, evoking the now submerged Bering land bridge that connected Siberia to Alaska during the glaciations, when the sea level was lower.

"Molecular data suggest a population substitution in South America since 9000. The people of Luzia have disappeared and have been replaced by living Amerindians nowadays, although both have a common origin in Beringia", said Hünemeier.

Brazilian contribution

The contribution of Brazilian researchers to the study was fundamental. Among the 49 individuals whose fossil DNA was extracted, seven skeletons dated from 10 100 to 9 100 years ago came from Lapa do Santo, a rock shelter in Lagoa Santa.

The seven skeletons, along with dozens of others, were found and exhumed during 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 conducted by Neves between 2002 and 2008 were funded by the São Paulo Research Foundation – FAPESP.

In total, the new study examined the fossil DNA of 49 individuals found at 15 archaeological sites in Argentina (two sites, 11 individuals dating from 8,900 to 6,600 years ago), in Belize (a site, three individuals dating from 9,400 to 7,300 years ago), Brazil (four sites, 15 individuals dated between 10,100 and 1,000 years ago), Chile (three sites, 5 individuals dated between 11,100 and 540 years) and Peru (7 sites, 15 individuals dated between 10 100 and 730 years).

The Brazilian skeletons come from the archeological sites of Lapa do Santo (seven individuals dated about 9,600 years ago), Jabuticabeira II in the state of Santa Catarina (a sambaqui or a shells shell with five individuals dating from about 2000 years ago), as well as two river corridors in the Ribeira Valley, São Paulo State: Laranjal (two individuals dated about 6,700 years old) and Moraes (an individual dated about 5 years ago). 800 years).

Paulo Antônio Dantas of Blasis, an archaeologist affiliated with the MAE-USP, led the excavations at Jabuticabeira II, also supported by FAPESP as part of a thematic project.

Levy Figuti, also an archaeologist at the MAE-USP, led the excavations at the river dike sites of the State of São Paulo, and also benefited from the support of FAPESP.

"The skeleton of Moraes (5,800 years old) and Laranjal's skeleton (6,700 years old) are among the oldest in southern and southeastern Brazil," said Figuti. "These sites are strategically unique because they lie between the high plateaus of the Atlantic plateau and the coastal plain, which significantly contributes to our understanding of how Southeast Brazil was populated."

These skeletons were discovered between 2000 and 2005. From the beginning, they exhibited a complex mix of coastal and continental cultural traits, and the results of their badysis generally varied, except in the case of a Paleoindian diagnosed skeleton (l & rsquo; Analysis of its DNA is not yet complete).

"The study that has just been published represents a major breakthrough in archaeological research, exponentially increasing what we knew a few years ago about the archaeogenetics of the settlement of the Americas," he said. said Figuti.

Hünemeier has recently made a significant contribution to the reconstruction of human history in South America with the help of paleogenomics.

Native American genetics

All human remains found on some of the oldest archaeological sites in Central America and South America did not belong to genetic descendants of the Clovis culture. The inhabitants of several sites did not have any DNA badociated with Clovis.

"This shows that besides its genetic contribution, the second wave of migration to South America, which was badociated with Clovis, may have also brought technological principles that would be expressed in the famous fishtail points that the Found in many parts of South America, "says Strauss.

The number of human migrations from Asia to the Americas at the end of the Ice Age over 16,000 years ago was until then unknown. The traditional theory, formulated in the 1980s by Neves and other researchers, was that the first wave had African traits or traits similar to those of Australian aborigines.

The well-known medico-legal facial reconstruction of Luzia was performed according to this theory. Luzia is the name given to the fossil skull of a woman who lived in the Lagoa Santa area 12,500 years ago. It is sometimes referred to as the "first Brazilian".

The Luzia bust with African features was constructed on the basis of skull morphology by British anatomical artist Richard Neave in the 1990s.

"However, the shape of the skull is not a reliable marker of ancestor or geographical origin." Genetics is the best basis for this type of inference, "explained Strauss.

"The genetic results of the new study categorically show that there was no significant connection between Lagoa Santa and groups in Africa or Australia." The hypothesis according to the new study shows categorically that there was no significant connection between Lagoa Santa and groups in Africa or Australia. which the inhabitants of Luzia would have come from a migratory wave anterior to the ancestors of the Amerindians of today has therefore been refuted.On the contrary, the DNA shows that the people of Luzia were entirely Amerindian. . "

A new bust replaced Luzia in the Brazilian scientific pantheon. Caroline Wilkinson, forensic anthropologist at Liverpool John Moores University in the UK and disciple of Neave, performed a facial reconstruction of one of the individuals exhumed in Lapa do Santo. The reconstruction was based on a digital model of the retroflexed skull.

"Accustomed as we are to the traditional reconstruction of Luzia's face with strongly African traits, this new reconstruction of the face reflects the physiognomy of the first inhabitants of Brazil with much more precision, showing the generalized and indistinct features from which the great Native American diversity has been established for years, "said Strauss.

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

"These monumental shell mounds were built about 2,000 years ago by populous societies that lived on the shores of Brazil." The badysis of fossil DNA from Santa mounds burials Catarina and São Paulo show that these groups were genetically related to the Amerindians living in southern Brazil, especially Kaingang groups, "he said.

According to Strauss, the extraction of DNA from fossils is technically very complex, especially if the material was found on a site subject to a tropical climate. For nearly two decades, extreme fragmentation and significant contamination prevented different research groups from extracting genetic material from the bones found in Lagoa Santa.

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

"The construction of the first archaeogenetic laboratory in Brazil is expected to begin in 2019, thanks to a partnership between the Museum of Archeology and Ethnology (MAE) of the University of São Paulo and its Institute of Bioscience ( IB) with funding from FAPESP to give a new impetus to research on the settlement of South America and Brazil, "said Strauss.

"To a certain extent, this study alters not only what we know about how the area was populated, but also dramatically the way we study human skeletal remains," said Figuti.

The human remains were first discovered at Lagoa Santa in 1844, when Danish naturalist Peter Wilhelm Lund (1801-1880) discovered about thirty skeletons at the bottom of a flooded cave. Almost all of these fossils are now found at the Natural History Museum of Denmark in Copenhagen. Only one skull remained in Brazil. Lund donated it to the Brazilian Institute of History and Geography of Rio de Janeiro.

Colonization by leaps and bounds

On the same day as Cell article was published (November 8, 2018), an article in the journal Science also reported new discoveries on the fossil DNA of early migrants in America. André Strauss is one of the authors.

Of the 15 old skeletons from which genetic material was extracted, five belong to the Lund collection in Copenhagen. They date from between 10,400 and 9,800 years ago. They are the oldest of the sample, alongside an estimated Nevada individual at 10,700 years old.

The sample included fossilized human remains from Alaska, Canada, Brazil, Chile, and Argentina. The results of his molecular badysis suggest that the settlement of the Americas by the first human groups in Alaska would not have been effected by the simple fact of the progressive occupation of the territory at the same time as the growth of the population.

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

The settlement of the Americas ensued in a giant leap, as small bands of hunter-gatherers traveled vast distances to settle in new areas until they reached the Tierra del Fuego in a movement of one or two thousand years at the most.

Among the 15 individuals whose DNA was badyzed, it was discovered that three of the five Santa Lagoa possessed Australian genetic material, as suggested by the theory proposed by Neves for the occupation of America. from South. The researchers are unable to explain the origin of this Australasian DNA or how it has been found in only a few of the inhabitants of Lagoa Santa.

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

Other fossils collected in the twentieth century include the Luzia skull, discovered in the 1970s. Nearly 100 skulls discovered by Neves and Strauss over the last 15 years are now preserved at the USP. A similar number of fossils are kept at the Pontifical Catholic University of Minas Gerais (PUC-MG).

But the vast majority of these osteological and archaeological treasures, belonging perhaps to more than 100 people, have been deposited in the National Museum of Rio de Janeiro and have most likely been destroyed in the fire that ravaged this historic building on 2 September 2018.

Luzia's skull was on display at the National Museum next to Neave's facial reconstruction. Scientists were worried that the fire would have lost it, but fortunately it was one of the first items recovered from the ruins. He had broken but survived. The fire destroyed the original facial reconstruction (of which there are several copies).