The demise of Neanderthals may have been much sexier than previously thought
The demise of the Neanderthals has been a mystery for some time, with explanations of competition for resources involving a wise manuntil a wise man kill them by force. However, a new article suggests the extinction was much more than we thought, wow wow, and their demise was blamed on the propensity to breed with a wise man.
Since scientists sequenced the genomes of a wise man and Neanderthals, we know that about 2 percent of the genome of humans outside of Africa comes from Neanderthals. Meanwhile, about 0.3 percent of African genomes come from Neanderthals because of crosses that take place afterwards a wise man left the continent between 60,000 and 90,000 years ago. However, if we look at Neanderthal DNA, we find no Homo sapien DNA.
In a new paper, researchers at the Natural History Museum assess possible reasons for DNA’s one-way exchange and discuss how these two groups interacted and did these “genetic exchanges.” They suggest that the inclusion of Neanderthals in the Homo sapien population could have helped lead to the demise of the Neanderthals.
“Our knowledge of the interaction between a wise man and Neanderthals has become more complex in recent years, but it’s still rare to see scientific discussions about how the interbreeding between the groups actually occurred,” said Natural History Museum study leader Professor Chris Stringer in a statement. press release.
“We propose that this behavior could have led to the extinction of Neanderthals if they had been breeding regularly with a wise manwhich would have eroded their populations until they disappeared.”
The team notes that when people and Neanderthals met again in Europe 60-90,000 years ago, it was hundreds of thousands of years since their divergence.
“Without knowing exactly how Neanderthals looked or behaved, we can only speculate what” a wise man would have thought of their relatives,” Stringer said. “The language differences would probably have been greater than we could have imagined, given the time depth of the separation, and would have been much greater than those between all modern languages.”
Yet we know that – despite these hurdles – genetic information was exchanged. The team points to mating between different chimpanzee groups, as well as between groups of hunter-gatherers, as possible models for what happened between a wise man and Neanderthals. Groups have been observed in chimpanzees grabbing females from rival groups, but males and females have also been observed secretly begging and making contact with rival group members away from their respective groups.
“More structured mate movements among recent hunter-gatherers vary according to local demographic conditions,” they write in the study, “and thus may have also evolved between Neanderthals and H. wise groups sometimes”.
What intrigued the team is the apparent one-way exchange of genetic information. In the 32 genomes of Neanderthals sequenced so far, we found no evidence of Homo sapien DNA. This could be because breeding between the two groups was only possible in one direction (as in Ligers, where a male lion mates with a female tiger). The lack of Neanderthal mitochondrial DNA (inherited through females) in living humans suggests that only male Neanderthals and females a wise man successfully produce offspring. It may also be the case that male hybrids were less fertile.
One possibility is that Neanderthals didn’t absorb a wise man in their groups, but Neanderthals were included in Homo sapien populations. The team argues that if further evidence suggests that Neanderthals were included in human populations, but not the other way around, it could explain the decline of Neanderthals.
“If fertile Neanderthals were regularly included in H. wise groups (by whatever mechanisms) during that period, they were also effectively removed from Neanderthal gene pools, and such consistent discharge of first-age individuals is not something that could have been sustained for long in small hunter-gatherer groups,” they write in the newspaper.
“Maybe Spread” H. wise groups acted like sponges absorbing pockets of late Neanderthals and perhaps that, like everything else, led to the eventual demise of Neanderthals as a viable population.”
The team adds that more evidence is needed and more Neanderthal genomes need to be sequenced to see if this is the case. This may come from DNA already found in cave sediments. At this point, we’ll have to wait and see what that evidence turns up, to know if Neanderthals achieved their goal of mating and integrating with humans, to the point where they couldn’t sustain their own dwindling populations.
“We don’t know if the apparent one-way gene flow is because it just didn’t happen, if the breeding happened but wasn’t successful, or if the Neanderthal genomes we have are not representative,” Stringer said.
“As more Neanderthal genomes are sequenced, we should be able to see if nuclear DNA from a wise man was passed on to the Neanderthals and shows whether this idea is correct.”
The newspaper is published in PaleoAnthropology.
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