(ORDO NEWS) — Scientists have presented the most complete evidence of ancient migrations in the New World to date.
Who and when settled South and North America are questions that scientists from various fields of knowledge, from archaeologists to geneticists, have been trying to answer for many decades.
So far, one thing is clear: people came to the New World later than to any other continent except Antarctica.
For a long time, it was believed that the first Americans were the carriers of the Clovis culture – traces of their stay in North and Central America are dated about 13 thousand years ago.
But subsequent findings by archaeologists, as well as studies of the genomes of Native Americans, showed that people arrived in the New World much earlier.
So, in 2013, paleontologists found mammoth bones in Texas, on which there were traces of carcass cutting.
Moreover, the tools turned out to be made from the bones of the same animal, and the dating surprised everyone: someone ate mammoth about 37 thousand years ago.
We don’t even know if people came to America by land (through the now flooded Beringia) or somehow sailed.
An equally murky issue is intracontinental ancient migration. Scientists from Florida Atlantic University and Emory University (both in the USA) tried to answer it.
They studied the ancient DNA of people found in the northeast of Brazil, added the results of genetic studies of the population of other parts of South America, and based on this they compiled a computer model of the migration routes of early Americans.
The researchers not only provided new genetic evidence supporting archaeological evidence of north-south migration towards South America, but also for the first time discovered migrations in the opposite direction along the Atlantic coast.
For some reason, people left the territory of modern Uruguay towards the current territory of Panama . The length of this route is 5277 kilometers, and the migrants made their way rather quickly.
The authors of the work argue that the settlement of the Atlantic coast occurred only after the settlement of most of the Pacific coast and the Andes.
This is very strange, because the eastern part of South America is clearly more habitable than the Andes or a narrow strip of the Pacific coast.
Scientists suggest that there is still some unrecorded population that lived closer to the Atlantic coast and was the reason that people whose genomes are known to us did not go to this coast.
The same population could have influenced the process of return migration, from south to north, to Panama – most likely, starting wars of conquest. It remains to identify the genetic markers of these people.
In addition to the map of intra-American migrations – the most complete to date – scientists have discovered some more details that have not yet been explained.
The traces of Neanderthal genes in the DNA of Americans are quite understandable and explainable – the closest relative and rival of sapiens was noted in the genome of many modern people.
But the genes characteristic of the inhabitants of Australia and Papua New Guinea, in ancient DNA from Panama, were already a surprise.
“There is a whole Pacific Ocean between Australia and America, and we still don’t know how these signs appeared in Central and South America without leaving traces in North America,” the paper says.
The surprises didn’t end there. It turned out that the ancient inhabitants of Uruguay and Panama had much more Denisovan than Neanderthal ancestors.
Almost all the inhabitants of Asia have a Denisovan admixture, and it was already known earlier that the indigenous population of America also had Denisovans in their ancestors.
But samples from Uruguay and Panama showed a much larger proportion of Denisovan DNA in American populations than ever before.
According to the authors of the work, the crossing of sapiens with Denisovans, which gave this admixture, should have occurred at least 40 thousand years ago.
The fact that the Denisovan lineage survived and its genetic trait was found in an ancient Uruguayan speaks of a much larger scale of interbreeding between the human and Denisovan populations – or of ways of settling the Americas that are older than those known to us today.
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