Nobel Laureate in Medicine Pioneers the 'Fossil DNA' of Neanderthals

This year’s Nobel Prize winner in Physiology or Medicine is Svante Pääbo, 67 year old Swede and geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The scientist led several researches that culminated in the publication of the first draft of the Neanderthal genome sequence, in 2010, and in the discovery of Denisovans, hominids contemporaneous with Neanderthals, whose fossils were found in the cave. of Denisova, located in the Altai Mountains, Siberia. Among the scientist’s contributions are also the record for the oldest human DNA ever studied and new paths opened in the study of diseases (including Covid) and human adaptations.

The laureate can be considered a father in this area of studies, called paleogenomics, which began in the 1980 years full of contamination concerns — he admitted, for example, that the DNA that extracted from an Egyptian mummy was probably his own. Patiently, the techniques were improved and the concern about contamination was resolved. At a press conference following the award announcement, Pääbo said he was still digesting the news, in disbelief after the Academy’s call. “I thought it was a prank played by the people in my group,” he declared.

Born in Stockholm, Pääbo and his collaborators have shown that modern humans have an important part of their DNA, smaller than 5 %, which came from Neanderthals and Denisovans. This contribution to the genetic material present in the nuclei of cells, called introgression by geneticists, is found between Europeans and Asians, in the case of Neanderthals, and only among Asian populations in the case of Denisovans. This means that between and a thousand years ago, the

Homo sapiens , when leaving Africa and finding other species of intelligent hominids on the Eurasian continent, they had fertile hybrid children with them that left billions of descendants. All Europeans and Asians, therefore, are “mixed races” between human species. As the introgression is small, this does not mean that these populations are genetically very different from African populations.

In 2018, the German laboratory where the scientist works announced the discovery of a woman who was a hybrid descendant of Neanderthals and Denisovans and lived 90 a thousand years ago. A single bone of hers has been preserved over time in Denisova Cave. The works of Svante Pääbo even allow us to infer that these fossils, in which he applied his own methods for the very delicate extraction of DNA degraded for tens to hundreds of millennia, do not tell the complete story, as is to be expected by the minority of skeletons that find ideal conditions for fossilization. Genomes indicate that there was at least one mysterious third lineage of hominids that also had children on rare occasions (introgressed) only with the Denisovans.

The scientist and his pupils also hold the record for the oldest Human DNA already sequenced: samples from Spain with an estimated age of 430 thousand years. The body of knowledge generated even makes it possible to know more about the health of Homo sapiens and their closest relatives: it has already contributed to a better understanding of schizophrenia and even severe Covid, and clarified that modern Tibetans owe their adaptations to the Himalayan altitude to the DNA they inherited from that Denisovan introgression. The fruits are numerous: last month, for example, a team of researchers showed that a genetic variant present only in Sapiens, but not in Neanderthals and Denisovans, causes more neurons to grow in tissues grown in the laboratory.

It cannot be underestimated how important Svante Pääbo’s work was in revolutionizing the understanding of the history of our species. He confirmed not only that the human family was more diverse than expected, but also that different species (or subspecies, depending on the kinship theory adopted) of people lived together in the same environments and had children, altering the fate of populations of animals. entire continents. It is unlikely that any of your colleagues will doubt your worthiness.

The mood among geneticists is festive. David Reich, a human population geneticist at Harvard who worked with Pääbo on the Neanderthal genome, told the journal Nature that he is inspired by his colleague. “He realized how special and unique this kind of data was,” added Reich. “The fact that a good fraction of people running around the world today have DNA from archaic humans like Neanderthals has important consequences for who we are.”

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