There is evidence that the Neanderthal and Homo sapiens lineages began to diverge about 600,000 years ago and then developed largely separately in Eurasia and Africa. Neanderthal fossils have been discovered in southern Siberia and throughout Asia and Europe. It is estimated that they spent at least 400,000 years adapting in this environment, where the climate was generally cooler than today.
The ancestors of our species, meanwhile, developed in Africa. Whether Homo sapiens are the direct descendants of a single group of prehistoric African hominids or the product of genetic mixing between other populations scattered across the continent is currently unknown.
A new study suggests Homo sapiens may be responsible for the extinction of Neanderthals. Not through violence, but through sex. In other words, making love would have put Neanderthals on the path of extinction.
According to the findings, interbreeding with our ancestors may have reduced the number of Neanderthals breeding with each other, ultimately driving them to extinction. The authors hope that improvements in DNA sequencing technology will resolve this hypothesis by making more genomes accessible, even though only 32 Neanderthal genomes have been sequenced to date, making it possible that the absence of Homo sapiens DNA in their genomes is a quirk of sampling. .
Professor Chris Stringer, the museum’s research lead in human evolution, said: “Our knowledge of the interaction between Homo sapiens and Neanderthals has become more complex in recent years, but it is still rare to see scientific discussions about how the interbreeding between the groups came about.”
“We propose that this behavior could have led to the extinction of Neanderthals if they regularly bred with Homo sapiens, which could have eroded their population until they disappeared.”
Based on genetic evidence, it appears that the two species first interacted when Homo sapiens began venturing beyond Africa at times about 250,000 years ago. There is still a lack of knowledge about how Neanderthals looked or behaved. Scientists can only speculate what Homo sapiens would have thought of their relatives.
Chris says, “The language barrier may have been reinforced by the individual characteristics of both species, with comparisons of Neanderthal and Homo sapiens suggesting that the species’ brains and vocal apparatus were different. Neanderthal genomes also show that nearly 600 genes were differentially expressed between our species and theirs, particularly those associated with the face and voice.
“Another striking difference would have been the forehead, with Neanderthals having a prominent brow ridge that could have been used for social communication.”
However, our predecessors may not have understood the messages these ridges were trying to send. According to several studies, homo sapiens were able to use their eyebrows to transmit a variety of finer, transient signals because they had fewer eyebrow ridges. These interactions eventually resulted in breeding between both species, but it’s unclear exactly how this happened.
Crossing at this time may have resulted from mutual courtship or may have been less friendly. Encounters between separate groups of our closest living relatives, chimpanzees, show evidence of both behaviors.
Depending on the specific breeding pair, crossings may or may not have taken place. In late Neanderthal genomes from between 40 and 60,000 years ago, there is currently no evidence of Homo sapiens genetics.
Chris said, “This may be due to the hybridization process itself, as some species can only produce offspring in certain directions. For example, pollen from the Capsella rubella plant can successfully fertilize Capsella grandiflora seeds, but not the other way around.”
“The lack of mitochondrial DNA, which is inherited by females, from Neanderthals in living humans has been suggested as evidence that only male Neanderthals and female Homo sapiens could mate, but there is also some evidence that male hybrids may have been less fertile than females. ”
“With fewer Neanderthals breeding with each other and group sizes already small and scattered because of the environment, hybridization outside Neanderthal family groups could help drive the species into decline. However, at this point there isn’t enough evidence to make a decision. to take.”
“As more Neanderthal genomes are sequenced, we should be able to see whether nuclear DNA was passed from Homo sapiens to Neanderthals and show whether or not this idea is correct.”
- Chris Stringer, Lucile Crete. Mapping interactions of H. neanderthalensis and Homo sapiens from the fossil and genetic records. PaleoAnthropology. DOI: 10.48738/2022.iss2.130