An international research team has revealed unexpected details about colonization in Central and South America when it was examining the first high-quality DNA data from these regions.
The results include two previously unknown genetic exchanges between North and South America, one of which represents continental population growth.
The results indicate that the people who spread the Clovis culture are the first widespread archeological culture of the North America had a greater demographic influence further south than previously thought.
The authors analyzed data from the genome of 49 individuals from Central and South America, some of whom were already 1
By comparing ancient and modern genomes from America and other parts of the world, the researchers succeeded in obtaining qualitatively new insights into the early history of Central and South America.
Published in the journal Cell the study was headed by researchers from Harvard Medical School; the Howard Hughes Medical Institute; the Max Planck Institute for the Science of Human History; the University of California, Santa Cruz; Pennsylvania State University; the University of New Mexico; the University of São Paulo and other institutions in Argentina, Australia, Belize, Brazil, Chile, the European Union, Peru and the United States.
Researchers received official permits to excavate ancient human remains and conduct analyzes, and they were consulted with local government agencies and indigenous communities.
Clovis compound among the oldest Central and South Americans
Between 11,000 and 9,000 years ago, a characteristic DNA type of the Clovis culture was found in Chile, Brazil and Belize.
"A key finding was that a Clovis cultivated man from North America has a distinct ancestry with the oldest Chilean, Brazilian, and Belizean individuals about 12,800 years ago," said co-author Cosimo Posth of the Max Planck Institute for the Science of Human History. "This supports the hypothesis that the spread of the people who spread the Clovis culture in North America has also reached Central and South America."
However, the Clovis culture-associated lineage is lacking among today's South Americans, and in ancient samples are less than 9,000 years old.
"This is our second key discovery," said David Reich, Associate Professor of Genetics at Harvard Medical School and an investigator at the Howard Hughes Medical Institute. "We showed that there was population replacement across the continent that started at least 9,000 years ago."
After population replacement, a remarkable genetic continuity occurred between ancient humans 9,000 years ago and modern humans from several countries in South American regions. This is in contrast to Western Eurasia and Africa, where there are few places with so much continuity.
Associated descent of California Channel Island in the Andes
. The second hitherto unknown distribution of humans was shown in an analysis that showed this ancient Californians from the Channel Islands have a strong common descent with groups that had spread in the southern Peruvian Andes at least 4,200 years ago.
The researchers say that this is unlikely that the population of the Channel Islands in South America is particularly widespread. Instead, they hypothesize that the connection between these regions is the result of extensions of humans that occurred thousands of years ago, and that this descent has spread to the Andes after later events in South America.
"It may be that this is the case The descent arrived in South America thousands of years ago, and we just do not have any previous people showing it," said Nathan Nakatsuka, a senior researcher at the Harvard Medical School Co-author of the study. "There is archaeological evidence that the population in the central Andes has risen sharply some 5,000 years ago, and the proliferation of certain subgroups during these events may be the reason why we discover this ancestry afterwards."
The promise of ancient DNA research in Americas
The researchers emphasize that their study only gives an insight into the discoveries that may arise from future work.
To get acquainted with the first movements of people in Central and South America, they say it would be necessary to obtain ancient DNA from individuals 11,000 years ago.
Even for the 11,000 to 3,000 years that this study focused on, the picture is far from complete.
"We did not have any ancient data from the Amazon, North-South America and the Caribbean, so we can not see how individuals in these regions relate to the regions we analyze," Reich said. "Filling these gaps should be a priority for future work."
"We are excited about the potential of research in this area," said Johannes Krause, co-author of the Max Planck Institute for the Science of Human History. "Future regional studies with large sample sizes allowed us to identify the potential of ancient DNA to show how human diversity has become as it is today."
First Peoples: Study finds two ancient ancestors that were "rediscovered" with the settlement of South America
Cell, Posth et al .: "Reconstruction of deep population history in Central and South America" DOI: 10.1016 / j.cell.2018.10.027, https://www.cell.com/cell/fulltext/S0092-8674(18 31380 -1