origin of humans; early sapiens Neanderthal mix (Origins)

by David Turell , Tuesday, October 24, 2023, 17:30 (394 days ago) @ David Turell

Not just in Europe:

https://www.sciencealert.com/unknown-human-lineage-found-buried-in-the-neanderthal-geno...

"As Homo sapiens migrated into Eurasia more than 70,000 years ago, much of the continent was already inhabited by Neanderthals, hominins who shared an ancestor with us but had spent roughly half a million years diverging.

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"During their Late Pleistocene overlap in Eurasia, however, we know the two hominin species sometimes interbred, since many humans today still have traces of Neanderthal DNA.

"And according to a new study, this relationship goes back even farther than we thought, with a long-forgotten earlier chapter re-emerging from clues in the Neanderthal genome.

"When modern humans reached Eurasia in the Late Pleistocene, the study suggests, Neanderthals living there already carried traces of our species' DNA, apparently from a much older, previously unknown run-in with an even more ancient lineage of anatomically modern humans.

"That would mean some Homo sapiens ventured into Eurasia more than 250,000 years ago, the study's authors report, long before the continent's earliest evidence of modern humans. For context, the fossil record indicates our species evolved in Africa only 300,000 years ago.

"'We found this reflection of ancient interbreeding where genes flowed from ancient modern humans into Neanderthals," says Alexander Platt, an evolutionary biologist at the University of Pennsylvania.

"'This group of individuals left Africa between 250,000 and 270,000 years ago. They were sort of the cousins to all humans alive today, and they were much more like us than Neanderthals," Platt says.

"The early modern humans who made it to Eurasia later died out, the researchers note, and Neanderthals continued to dominate the continent for another 200,000 years or so. Hidden in the Neanderthal genome, however, were remnants from this ancient encounter.

"To reveal this, the study's authors first followed clues uncovered by another recent study, which found Neanderthal-like chunks of DNA – called Neanderthal-homologous regions (NHRs) – in multiple present-day human populations from Africa.

"This was surprising, since most interbreeding between modern humans and Neanderthals likely happened in Eurasia. It raised questions about how Neanderthal DNA, typically associated with Eurasian ancestry, could be seemingly abundant in Africa.

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"NHRs were found in every population tested, showing they are widespread in Africa. Most of this 'Neanderthal-like' DNA originated not with Neanderthals, however, but with ancient modern humans who migrated from Africa to Eurasia about 250,000 years ago.

"As the newcomers interbred with Neanderthals, they left a legacy: Up to 6 percent of the Neanderthal genome came from early members of our species, the researchers report.

"The study also found evidence that, in certain populations, Neanderthal genes were introduced by people migrating back to Africa from Eurasia, where their ancestors had presumably interbred with Neanderthals."

Comment: Lot's more intermixing/interbreeding than realized. Sapiens were obviously prone to migration looking for the best area to live.