The debate about the cognitive capacity of Neanderthals, the human species closest to ours, disappeared about 40,000 years ago, seems increasingly closed in the scientific community: they were as intelligent, skilled, supportive and creative as us, the Homo sapiens. But now, the new genetic discoveries open an even more challenging debate: what if, in fact, they were not extinct? Driven by new analyzes of fossil DNA, some experts point out that Neanderthals are still here because we are us, since there was an integration between the two species.
The more genetic material that can be extracted and analyzed from remote prehistory – not an easy thing, because the older the DNA, the more difficult it is for it to give reliable results – it becomes more evident that Neanderthals and humans maintained constant interbreeding. Magazine Nature revealed this Wednesday the DNA analysis of four European individuals from 45,000 years ago: all of them had ancestors, more or less direct, Neanderthals. And it is not the first to occur: the other two genomes of Homo sapiens from that time that have been analyzed also reveal hybridization between the species, in one case, moreover, very recent (his great-great-grandfather belonged to the other species).
Oldest genome reveals continued sex with Neanderthals
Neanderthals, the lonely humans
If you cross them between Neanderthals and Homo sapiens Had they been rare and highly localized in time and space, these results would be the scientific equivalent of finding a needle in the immense haystack of prehistory. The fact that direct ancestors appear over and over again indicates a pattern. It is not clear how many human migratory waves came from Africa to Europe and Asia, or when they occurred. Nor what happened to the human beings – Neanderthals and Denisovans – who were there when our species arrived. But it is evident that they maintained much more than friendly relations, as shown by the results obtained by the team of Svante Pääbo, the Swedish geneticist who has revolutionized the investigation of human evolution thanks to the analysis of ancient DNA and who obtained the first complete genome of a Neanderthal.
“The Neanderthal footprint is very present, in six or seven previous generations,” explains Antonio Rosas, a paleoanthropologist at the Spanish National Research Council (CSIC) and one of the great European experts on Neanderthals. “When more recent remains were analyzed, it appeared that hybridization had been more sporadic; but the new results show that it is much more frequent ”, adds this researcher who, however, does not share the theory of the“ dilution of Neanderthals in the human population ”.
“It seems like a bit of a good vision to me,” Rosas continues. “The Cro-Magnons analyzed are clearly sapiens from a phenotypic point of view: they are not Neanderthals, nor are they a mix. But there is no doubt that these new discoveries reopen the debate about the possibility of an integration of Neanderthals and Neanderthals. sapiens. It is possible that in some places this phenomenon occurred; but it is also probable that in others the Neanderthals were extinct ”. Factors such as geography or climate could influence extinction or integration.
Other experts believe, instead, that these results clearly demonstrate that the extinction did not occur, but that the Neanderthals were absorbed by the sapiens. Raquel Pérez Gómez, an expert biologist in genetics and a doctor in Veterinary Sciences from the Complutense, published an article three years ago in EL PAÍS in which she pointed out that paleogenetics was undermining the idea that they are two different species. “These results confirm (even more if possible) the position that it is not possible to speak of species, neither of hybrids, nor of the extinction of Neanderthals,” Pérez Gómez points out by email.
“In science, concepts are fundamental,” continues Pérez Gómez. “According Mayr Y Dobzhansky, it is accepted that a species biological is a group (or population) natural of individuals that can interbreed and generate fertile offspring. The more fossils that are sequenced, the more interbreeding events between Neanderthal and human populations migrating from Africa are documented. The more information we have, the more complete the genetic map and the evolutionary history of our species will become. And despite all the resistance, within a few decades it will be clear from the weight of the evidence that Neanderthals were humans like us, with characteristics, let’s call them, archaic”.
The interesting thing is that the hybridization process did not take place the other way around: in recent European Neanderthals no DNA remains of sapiens, which would indicate that modern humans they adopted Neanderthals; but these did not coexist in their groups with modern humans. Although, as always in prehistory, the more that is known, the more mysterious everything becomes: Antonio Rosas recalls that, on the other hand, in older Siberian Neanderthals, from about 100,000 years ago, traces have been found sapiens.
What seemed impossible not so long ago is becoming reality. When the movie was released in 1981 In search of fire, Jean Jacques Annaud’s version of the classic novel by JH Rosny Aîné was widely criticized because it showed a sex scene between a sapiens and a Neanderthal. Palaeogenetics has confirmed this, but it also emphasizes something that has a clear contemporary reading: the study of prehistory shows us that it is absurd to speak of races, that humanity is the result of an infinite crossing. We, modern humanity, are an endless mix, spanning centuries and millennia.