The disappearance of Neanderthals has been a mystery for some time, with explanations for competition for resources with A wise manat A wise man finish them with violence. However, a new paper suggests the extinction was much more bow chicka wow wow than we thought, blaming their disappearance on the tendency to breed with A wise man.
Since scientists sequenced the genomes of A wise man and Neanderthals, we know that about 2% of the genome of humans living outside of Africa comes from Neanderthals. Meanwhile, about 0.3% of the genomes of Africans come from Neanderthals due to the interbreeding that took place after A wise man left the continent between 60,000 and 90,000 years ago. However, when you look at Neanderthal DNA, you don’t find Homo sapiens DNA.
In a new paper, researchers from the Natural History Museum assess possible reasons for the unidirectional DNA exchange and explain how these two groups interacted with each other and effected these “genetic exchanges”. They suggest that the absorption of Neanderthal individuals into the Homo sapiens population could have contributed to the death of Neanderthals.
“Our knowledge of the interaction between A wise man and Neanderthals have become more complex in recent years, but it is still rare to see scientific discussion of how interbreeding between the groups actually occurred,” said Professor Chris Stringer, head of research at the Natural History Museum, in a press release.
“We propose that this behavior could have led to the extinction of Neanderthals if they bred regularly with A wise manwhich could have eroded their population to extirpation.”
The team notes that when humans and Neanderthals met again in Europe 60-90,0000 years ago, it had been hundreds of thousands of years since their divergence.
“Without knowing exactly what Neanderthals looked or behaved like, we can only speculate on what A wise man would have thought of their loved ones,” Stringer said. “The linguistic differences would probably have been greater than we could imagine, given the temporal depth of the separation, and would have been much greater than those between any modern languages.”
Nevertheless, we know that, despite these obstacles, genetic information has been exchanged. The team says mating between different groups of chimpanzees, as well as between groups of hunter-gatherers, is a possible model of what happened between A wise man and Neanderthals. In chimpanzees, groups have been observed seizing females from rival groups, but males and females have also been observed secretly soliciting and mating with members of rival groups away from their respective groups. .
“More structured mate movements among recent hunter-gatherers vary with local demographic conditions,” they write in the study, “and thus may also have developed between Neanderthal and H. wise sometimes groups.
What intrigued the team was the apparent one-way exchange of genetic information. In the 32 Neanderthal genomes that have been sequenced so far, we have found no evidence of Homo sapiens 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 (which is inherited by females) in living humans suggests that only male and female Neanderthals A wise man could successfully produce offspring. Male hybrids may also be less fertile.
One possibility is that Neanderthal groups did not absorb A wise man in their groups, but the Neanderthals were absorbed in Homo sapiens populations. The team argues that if other evidence suggests that Neanderthals were absorbed into human populations, but not the other way around, this could provide an explanation for the decline of Neanderthals.
“If fertile Neanderthals were regularly absorbed into H. wise groups (regardless of the mechanisms) during this period, they were effectively also removed from the Neanderthal gene pools, and such a constant flight of individuals into the prime of life could not have been sustained for long in small groups of hunter-gatherers” they write in the diary.
“Maybe disperse H. wise acted like sponges in the absorbent pockets of later Neanderthals and perhaps this, as much as anything else, led to the eventual demise of Neanderthals as a viable population.”
The team adds that more evidence is needed and that more Neanderthal genomes need to be sequenced to see if this is the case. This may be from DNA already found in cave sediments. For now, we have to wait and see what this evidence reveals, to find out if Neanderthals achieved their ends by mating and integrating with humans, to the point that they couldn’t support their own dwindling populations. .
“We don’t know if the apparent one-way gene flow is because it just wasn’t happening, that reproduction was happening but not successful, or if the Neanderthal genomes we have don’t are not representative,” Stringer said.
“As more and more Neanderthal genomes are sequenced, we should be able to see if nuclear DNA from A wise man was transmitted to Neanderthals and demonstrate whether or not this idea is correct.”
The article is published in PaleoAnthropology.
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