July 25, 2021

Ancient DNA helps unravel the tangle of American colonization

Ancient DNA helps unravel the tangle of American colonization

The analysis of the genome of fifteen American individuals, among them that of the oldest mummy in the world, have placed some order on the complex map of the dispersal of the first colonizers of America, who spread across the continent in three major events. This is one of the main conclusions of a work published by Science, led by scientists from the Museum of Natural History of Denmark and that helps unravel the tangle that is still the settlement of the American continent.

The ancestors of the current Americans left Siberia and East Asia and, after remaining thousands of years isolated in the current Bering Strait, they entered twenty-five years ago in the non-glacial zones of the American territory, from where they were expanding throughout the continent. First they moved to what is now Alaska and Canada, then they went to the south of the continent, reaching Patagonia and later they left from Mesoamerica to the south and again to the north.

The first occurred through the Beringia bridge since approximately twenty-five thousand years until approximately thirteen thousand. The second important period is the one that implies the colonization of almost the whole continent towards the south, until Patagonia: this was very fast and it did not take place gradually, but rather as small jumps, and took place fourteen thousand years ago and it remained until six thousand. The third and last great wave started in present-day Mexico about 8,700 years ago. This last one would give rise to most of the genetic variability observed today in the south of the continent, which in this occasion this dispersion would not reach Patagonia Until about five thousand years ago.

"We have managed to place the anchors at certain points in the history of America," says Antonio Salas, of the University of Santiago de Compostela, who points out that it is a preliminary step to begin to understand the great complexity of this colonization. In the second large dispersion the researchers found something unexpected, a "phantom DNA". In the remains analyzed at the site of Lagoa Santa, Brazil, they found an austral-Asian component in their genomes that is believed to have arrived there from Mesoamerica and that the first settlers could drag to the south;

However, they do not know its origin and how it arrived in Mesoamerica: "We know that this genetic signal is present in Brazil. more than ten thousand years but we have not yet been able to find a single genome older or more north of Lagoa Santa that had this component. "The genome of this mummy not only solved a legal and cultural dispute, but helped, along with the other fourteen individuals, to Draw the population of the continent.


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