The story of the American population has just been re-interpreted. 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 American ethnic groups, past and present.
Over 17,000 years ago, this original quota crossed the Bering stretch from Siberia to Alaska and began to host the New World. Fossil DNA shows an affinity between this migration stream and the populations of Siberia and northern China. Contrary to traditional theory, it had no link to Africa or Australasia.
The new study also reveals that when they had settled in North America, subsequent migration flows were diversified in two lines around 16,000 years ago.
The members of a line stretched over Isthmus in Panama and lived in South America in three different consecutive waves.
The first wave occurred between 15,000 and 11,000 years ago. The other took place no more than 9000 years ago. There are fossil DNA records from both migrations throughout South America. The third wave is much later, but its influence is limited when it occurred 4,200 years ago. Its members settled in central Andes.
An article about the study has just been published in the newspaper Cell a group of 72 researchers from eight countries affiliated with the University of Sao Paulo (USP) in Brazil, Harvard University in the United States and the Max Planck Institute for Science of Human History in Germany.
According to the researchers' conclusions, the line made between the north and south between 16,000 and 15,000 years ago belonged to the Clovis culture, named for a group of archaeological sites excavated in the western US and from 13 500-11 000 years ago.
The Clovis culture was so named when flint spikes were found in the 1930s at a digging in Clovis, New Mexico. Clovis sites have been identified throughout the United States and in Mexico and Central America. In North America, the Clovis people Pleistocene chased megafaunas as giant sluts and mammoths. With the decline of megafauna and its eradication 11,000 years ago, the Clovis culture finally disappeared. Long before, bands of hunter-collectors had traveled south to explore new hunting fields. They ended up in Central America, as evidenced by 9,400-year-old human fossil DNA found in Belize and analyzed in the new study.
At a later date, Clovis hunters-gatherers in Panama crossed and spread to South America, as evidenced by genetic data from burial places in Brazil and Chile, which was now revealed. This genetic evidence confirms well-known archaeological finds such as the Monte Verde site in southern Chile, where people slaughtered mastodons 14,800 years ago.
Among the many famous Clovis sites is the only burial site associated with Clovis tools in Montana, where remains of a boy (Anzick-1) were found and dated 12,600 years ago. DNA extracted from these bones has links to DNA from skeletons of people living between 10,000 and 9,000 years ago in caves near Lagoa Santa, Minas Gerais State, Brazil. In other words, the Lagoa Santa people were partially descendent of Clovis immigrants from North America.
"From a genetic point of view, the Lagoa Santa people are descendants of the first Americans," said archeologist André Menezes Strauss, who coordinated the Brazilian part of the study. Strauss is connected to the University of Sao Paulo's Museum of Archeology and Ethnology (MAE-USP).
"Surprisingly, the members of this South American's first position left no identifiable descendants among today's Americans," he said. "Some 9000 years ago, their DNA completely disappears from the fossil samples and replaced by DNA from the first wave of pre-Clovis culture. All living Amerindians are the descendants of this first wave. We do not yet know why the genetic stock of the Lagoa Santa people disappeared . "
One possible reason for the DNA disappearance from the second migration is that it is diluted into American DNA, which is the consequence of the first wave and can not be identified by existing methods of genetic analysis.
According to Tábita Hünemeier, a genetician at the University of Sao Paulo Bioscience Institute (IB-USP), who participated in the research, "was one of the most important findings of the study identification of Luzias people genetically related to the Clovis culture, which discontinues the idea of two biological components and the possibility that there were two migrations to America, one with African characteristics and the other with Asian moves. "
"Luzia's people must have come as a result of a migratory wave originating in Beringia," she said, referring to the now immersed Bering land bridge that went with Siberia to Alaska under the iceberg when the sea level was lower.
"The molecular data suggests population exchange in South America since 9000 years ago. Luzi's people disappeared and replaced by the American individuals today, although both had a common origin in Beringia," said Hünemeier.
The Brazilian researchers' contribution to the study was fundamental. Among the 49 individuals from which fossil DNA was taken, seven skeletons were dated to between 10 100 and 9 100 years ago from Lapa do Santo, a mountain guard in Lagoa Santa.
The seven skeletons, along with dozens of others, were found and arose in subsequent archaeological campaigns on the site, initiated 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 the São Paulo Research Foundation – FAPESP.
In summary, the new study investigated fossil DNA from 49 people in 15 archeological sites in Argentina (two sites, 11 people dating between 8 900 and 6 600 years ago), Belize (one place, three people dated between 9 400 and 7 300 years ago) Brazil (four places, 15 people dating between 10,100 and 1,000 years ago), Chile (three places, five individuals dating between 11,100 and 540 years ago) and Peru (seven places, 15 people dating between 10,100 and 730 years ago) .
The Brazilian skeletons come from the archaeological sites Lapa do Santo (seven individuals dating back 9,600 years ago), Jabuticabeira II in the Santa Catarina State (a sambaqui or scallop with five individuals dating about 2,000 years ago), as well as from two river basins in Ribeira Valley, São Paulo State: Laranjal (two individuals dating about 6,700 years ago) and Moraes (an individual dated about 5 800 years ago).
Paulo Antônio Dantas de Blasis, an archaeologist affiliated with the MAE-USP, led the tomb of Jabuticabeira II, which was also supported by FAPESP through a thematic project.
The graves at the river center of São Paulo state were led by Levy Figuti, also an archaeologist at MAE-USP, and also supported by FAPESP.
"The Moraes skeleton (5,800 years old) and the Laranjal skeleton (6 700 years old) are among the oldest from south and southeast of Brazil," said Figuti. "These sites are strategically unique because they are located between the Atlantic and the Atlantic, and make a significant contribution to our understanding of how South East Asia in Brazil was popular."
These skeletons were found between 2000 and 2005. Initially, they presented a complex blend of coastal and inland cultural characteristics, and the results of their analysis generally varied, except in the case of a skeleton diagnosed as Paleoindian (analysis of its DNA is not yet complete ).
"The study just published represents an important advance in archeological research, which exponentially increases what we knew only a few years ago about the archeogenetics of the American population," said Figuti.
Hünemeier has also recently made an important contribution to the reconstruction of human history in South America using paleogenomics.
Not all human remains found in some of the oldest archaeological sites in Central and South America belonged to genetic descendants of the Clovis culture. The residents in several places did not have Clovis-associated DNA.
"This shows that in addition to the genetic contribution, the second migration wave to South America, which was Clovis-associated, could also have included the technical principles that would be expressed in the known fishing pole points found in many parts of South America." Strauss said.
How many human migrations from Asia came to America at the end of the Ice Age more than 16,000 years ago, so far, was unknown. The traditional theory, formulated in the 1980s by Neves and other researchers, was that the first wave had African characteristics or characteristics similar to the Australian Aborigines.
The well-known forensic face construction of Luzia was performed in accordance with this theory. Luzia is the name of the fossil shell of a woman who lived in the Lagoa Santa region 12 500 years ago and is sometimes called "first brazilian".
The bust of Luzia with African characteristics was built on the basis of the skull's morphology by British anatomical artist Richard Neave in the 1990s.
"Skull form, however, is not a reliable marker of ancestry or geographical origin. Genetics is the best foundation for this kind of inference," Strauss explained.
"The genetic results of the new study show categorically that there was no significant relationship between the Lagoa Santa people and groups from Africa or Australia. So the hypothesis that Luzi's people derive from a migrating wave before the ancestors of today's Amerindians have been contradictory. On the contrary, The DNA that Luzias people were completely American. "
A new bust has replaced Luzia in the Brazilian scientific pantheon. Caroline Wilkinson, a forensic anthropologist at Liverpool John Moores University in Great Britain and a disciple of Neave, has produced a facial reconstruction of one of the individuals raised at Lapa do Santo. The reconstruction was based on a retro-shaped digital model of the skull.
"This new facial reconstruction is used to the traditional facial reconstruction of Luzia with strong African characteristics, reflecting the Brazilian physiognomy of the first inhabitants in much more detail, showing the generalized and countless features that the great American diversity was established for thousands of years," Strauss said.
The study published in Cell, he added, also presents the first genetic data on the Brazilian Coastal Cambaquis.
"These monumental shells were built 2,000 years ago by populated populations living on the Brazilian coast. Analysis of fossil DNA from shell cuttings in Santa Catarina and São Paulo shows that these groups were genetically related to the American individuals living today in southern 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 place with a tropical climate. For almost two decades, extreme fragmentation and significant contamination prevented various research groups from successfully extracting genetic material from the bones found at Lagoa Santa.
This has now been done thanks to methodological advances developed by Max Planck Institute. As Strauss enthusiastically explained, much remains to be discovered.
"The building of Brazil's first archeogenetic laboratory is scheduled to begin in 2019, thanks to a partnership between the Sao Paulo University Museum of Archeology and Ethnology (MAE) and its bioscience institute (IB) with funding from FAPESP. Clearly, it will provide a new driving force for research on the people of South America and Brazil, Strauss said.
"To a certain extent, this study not only changes what we know about how the region was popular but also significantly changes the way we study human skeletal remains," Figuti said.
Human goods were first found in Lagoa Santa 1844, when Danish natural scientist Peter Wilhelm Lund (1801-1880) discovered 30 skeletons deep in a flooded cave. Almost all of these fossils now exist at Denmark's Natural History Museum in Copenhagen. A single skull has stayed in Brazil. It was donated by Lund to the Brazilian History and Geography Institute in Rio de Janeiro.
Colonization on the go
Same day as Cell Article published (November 8, 2018), a newspaper in the newspaper Science also reported new findings about fossil DNA from the first migrants to America. André Strauss is one of the authors.
Among the 15 ancient skeletons from which genetic material was taken, five belong to the Lund Collection in Copenhagen. They run from 10 400 to 9 800 years ago. They are the oldest in the test, along with an individual from Nevada estimated at 10 700 years old.
The sample included fossil human residues from Alaska, Canada, Brazil, Chile and Argentina. The results of the molecular analysis suggested that the people of America of the first human groups from Alaska did not come solely through gradual occupation of territory at the same time as population growth.
According to the researchers responsible for the study, the molecular data suggests that the first people invade Alaska or neighboring Yukon, divided into two groups. This occurred between 17 500 and 14 600 years ago. One group colonized North and Central America, the other South America.
The American people followed as small tribes of hunter-gatherers rose to settle in new areas until they came to Tierra del Fuego in a movement lasting one or more two millennia.
Among the 15 individuals whose DNA was analyzed, three of Lagoa Santa five showed some genetic material from Australasia, as suggested by Neves theory of employment in South America. The researchers can not explain the origins of this Australasian DNA or how it ended up in just some of the Lagoa Santa people.
"The fact that Australasia's genomic signature has been present for 10,400 years in Brazil but is missing in all those tested to date, which is as old or older, and found further north, is a challenge in view of its presence in Lagoa Santa," they said. .
Other fossils gathered during the twentieth century include the Luzia shell found in the 1970s. Almost 100 skulls excavated by Neves and Strauss for the past 15 years are now held at the USP. A similar number of fossils are held at the Pontifical Catholic University of Minas Gerais (PUC-MG).
However, the vast majority of these osteological and archaeological treasures belonging to more than 100 people were deposited at the National Museum of Rio de Janeiro and probably destroyed in the fire ravaged by this historic building on September 2, 2018.
The Luzia shells were exhibited at the National Museum together with Neave's face reconstruction. Researchers feared it had been lost to the fire but fortunately it was one of the first items that would be recycled from the ruins. It had broken but survived. The fire destroyed the original facial reconstruction (of which there are several copies).