Evolution and humans: Neanderthal interbreeding (Evolution)

by David Turell , Thursday, July 06, 2017, 16:41 (2695 days ago) @ David Turell
edited by David Turell, Thursday, July 06, 2017, 16:58

Much earlier than thought:

http://www.the-scientist.com/?articles.view/articleNo/49806/title/Neanderthal-Human-Int...

"An analysis of a Neanderthal femur found in a German cave suggests that species was mixing it up with humans more than 270,000 years ago, researchers reported yesterday (July 4) in Nature. The authors compared mitochondrial DNA from the femur to mitochondrial DNA from other Neanderthals’ bones and modern humans, finding that it was more similar to the latter. They also dated the bone to about 124,000 years ago.

"The result was puzzling, as modern humans were thought to have established themselves on continents outside Africa much more recently—about 70,000 years ago. Study author Cosimo Posth of the University of Tübingen in Germany tells the New York Times that early members of our own species may in fact have left Africa and bred with Neanderthals more than 270,000 years ago.

“'We are realizing more and more that the evolutionary history of modern and archaic humans was a lot more reticulated than we would have thought 10 years ago,” coauthor Fernando Racimo, a postdoc at the New York Genome Center, tells New Scientist.

"Previous work has established that these gene swaps were a two-way street, with modern humans retaining genetic traces—some of them adaptive—of our Neanderthal ancestors
“There is this joke in the population genetics community—there’s always one more interbreeding event,” researcher Sergi Castellano, a population geneticist at the Max Planck Institute for Evolutionary Anthropology in Germany who was not involved in this study, told Nature last year. He predicted, “as more early modern humans and archaic humans are found and sequenced, we’re going to see many more instances of interbreeding.'”

Comment: Consensual sex or rape? Could they have spoken to each other?

Another article:

https://www.newscientist.com/article/2139694-we-may-have-mated-with-neanderthals-more-t...

"'There is ample evidence of breeding between Neanderthals and the ancestors of modern humans some 50,000 years ago. “Everyone knows Neanderthals gave us genes,” says Cosimo Posth at the Max Planck Institute for the Science of Human History in Leipzig, Germany.

"'Analysis of mitochondrial DNA from a Neanderthal femur found in south-western Germany now adds to evidence that there was earlier interbreeding. The DNA in the energy-producing mitochondria in our cells is different from that in our cell nuclei, and is passed only down the female line.

***

"'Puzzlingly, the mtDNA in Neanderthal bones is more similar to that of modern humans than it is to that of the Denisovans.

"'Posth and his colleagues looked at differences between the mtDNA in this femur and in other Neanderthals, and used mutational rates to calculate that the bone is 124,000 years old. The approach also indicates that this Neanderthal split from all other known Neanderthals sometime between 316,000 and 219,000 years ago. Yet it still contains key elements of early human mtDNA.

***

"'The results also suggest that Neanderthals had a much greater genetic diversity and larger population than we realised.

"'This study broadens our view, from the genetic perspective, of who the Neanderthals were as a species, says Toomas Kivisild at the University of Cambridge. “Previous work based on more than a dozen Neanderthal samples whose mitochondrial DNA had been sequenced has portrayed Neanderthals as a species of very low effective population size and genetic diversity,” he says.'"

Comment: The addition of sapiens DNA did not help the Neanderthals survive.