Although rumors had been swirling in the hallways for days, Annual Meeting of the Society for Molecular Biology and EvolutionWhich was held this year in Puerto Vallarta, Mexico, with the intervention of population geneticist Stephane Perini, from the Max Institute … Plank, from evolutionary anthropology, had everyone in the crowded room shifting in their seats: “I am pleased to report,” Perini said, “a new Denisovan genome from a male from 200,000 years ago.”
The interest and surprise of the audience was more than justified, because this genome is the oldest that has been obtained so far, and it exceeds the previous record by no more and no less than the previous record, which is the genetic load of the Neanderthal man who lived about 120 thousand years ago.
It is therefore an impressive scientific achievement. However, none of them have been published yet, but Perini assures that they will soon see the light of day in a peer-reviewed scientific journal. This result, the second Denisovan genome we have, comes after more than a decade of efforts to find fossil remains of this still mysterious species, a “cousin” of the Neanderthals, whose first news came only 14 years ago thanks to the analysis of DNA extracted in the Siberian Denisova Cave from a single small piece of the little finger of a girl who lived between 60,000 and 80,000 years ago.
According to Perini, the analysis conducted with his colleagues reveals that the individual comes from an early group of Denisovans who interbred several times with a group of Neanderthals whose population has not yet been discovered. In short, while the article is full of data, it seems that we have a new and powerful source of information about this mysterious human species.
mysterious type
Denisovans are known primarily by their DNA, not their fossil remains. So far, researchers have the girl’s genome, as well as some DNA fragments from widely scattered fossils (teeth, toe bone…) of seven other individuals, all found in the same Denisova Cave.
Later, scientists also identified traces of Denisovan DNA in modern populations, such as Papuans and Chinese, suggesting that, at least in Asia, those ancient groups interbred with our own species. However, despite their best efforts to figure out what they looked like, no one really knows what the Denisovans looked like.
As Perini explains, his breakthrough comes from the genetic analysis of a 200,000-year-old molar tooth found deep in the Denisova Cave by Russian archaeologist Maxim Kozlykin, who decided to send it to the Max Planck Institute in Germany. There, Perini and his colleagues were able to extract an extraordinary amount of DNA, which they then compared with that of other Denisovans, as well as that of Neanderthals and modern humans.
Different population
The analysis revealed that the Denisovan male had inherited 5 percent of his genome from a previously unknown group of Neanderthals. The individual, named Denisova 25, came from a different population than the girl, known as Denisova 3, and also from other Denisovans in the cave.
All of this, Perini explained in his talk, suggests that the ancient population to which the male belonged was replaced in the cave by more modern Denisovans. The data also suggest that the ancient Denisovans interbred several times with Neanderthals, who for a time (about 120,000 years ago) displaced the Denisovans from the cave.
However, about 60,000 years ago, as evidenced by the girl’s little finger, the Denisovans were in the cave again. It is also possible that the two groups coincided there: DNA from a bone fragment from a woman more than 50,000 years ago shows that her mother was a Neanderthal and her father was a Denisovan.
Later, both DNA and fossil evidence indicate that modern humans occupied the cave and that both Denisovans and Neanderthals disappeared. The area was clearly a crossroads for different human species, Perini said.
Although Denisovans and Neanderthals interbred repeatedly, scientists have long since concluded that their lineages are distinct, diverging from a common ancestor at least 400,000 years ago. Neanderthal ancestors settled in Europe and the Middle East, while Denisovans moved east into Asia, where they evolved separately, acquiring some 300,000 genetic changes that, the new genome reveals, forever separated them from Neanderthals.
Since then, Neanderthals and Denisovans have remained separate groups that only intermingled at the borders of their respective geographic regions. Now, all that remains is for Perini to publish his work so that the scientific community can learn more about this mysterious human species.
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