(ORDO NEWS) — An international team of scientists has built a map of human settlement in South America. South America is the last continent inhabited by humans. Settlement began about 10,000 years ago.
But until now it was not clear exactly how the process of migration across the vast continent proceeded.
Scientists have reconstructed the routes along which people moved, and found in them the genes of Neanderthals, Denisovans and, quite unexpectedly, Australians.
The people who settled South America carried the genes of the Australians. How these genes could get to South America across the ocean is completely incomprehensible.
South America was the last continent inhabited by humans. This has been known for a long time, but it still remains unknown how people moved during migration.
It is clear that initially they went from north to south – from Panama to Tierra del Fuego along the Pacific coast.
Using ancient human DNA recovered from archaeological sites in northeast Brazil, modern genome data, and powerful genomic analysis algorithms, Florida Atlantic University researchers, in collaboration with Emory University, have unraveled the ancient demographic history of South America.
How was the migration
Researchers have presented genetic evidence supporting existing archaeological evidence of north-south human migration along Pacific South America, but for the first time, they have found traces of migration in the opposite direction, along the Atlantic coast.
The first groups entered South America from North America about 10 thousand years ago and spread along the Pacific coast, populating the Andes (yellow arrow).
Shortly thereafter, at least one split occurred, with the first groups settling the Atlantic coast (green arrow). New migrations took place along the Atlantic coast.
People went north towards Panama and south to Uruguay (purple double arrow). This migration occurred relatively recently – about 1000 years ago.
Neanderthals, Denisovans… and Australians
The researchers used teeth from ancient specimens collected from archaeological sites in northeastern Brazil. Genome analysis unexpectedly found strong Australasian (Australian and Papua New Guinea) genetic signals in the genome from Panama.
“The Pacific Ocean stretches between Australasia and the Americas, and we still don’t know how these genomic signals appeared in Central and South America without leaving any traces in North,” said lead author Andre Luis Campelo dos Santos.
The researchers also found that in the genomes of people from Uruguay and Panama, the proportion of genes of Denisovan origin is significantly larger than that of Neanderthal.
(The Denisovans are an extinct Homo group, first identified by DNA taken from a fingertip in 2008. We wrote about their discovery in detail).
John Lindo, co-author of the paper, says: “Crossing with the Denisovans probably occurred long before the settlement of America, perhaps 40,000 years ago.
The fact that the Denisovan lineage survived, and its genetic signal was reflected in the genome of an ancient man from Uruguay, who is only 1,500 years old, suggests that the mixing was quite intense.”
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