The DNA sequencing of 5 Neanderthals brings new data on the final phase of their history

Neanderthal Molar from Belgium (Image courtesy I. Crevecoeur. All rights reserved)
Neanderthal Molar from Belgium (Image courtesy I. Crevecoeur. All rights reserved)

An article published in the journal “Nature” describes a research that helps the reconstruction of the final phase of Neanderthals’ history. A team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced the genome of 5 individuals of that species who lived between 39,000 and 47,000 years ago. These individuals are more closely related to those who interbred with modern humans than to an older individual from the Altai mountains whose DNA was sequenced some time ago.

The Max Planck Institute for Evolutionary Anthropology is at the forefront of paleogenetics, the application of genetic techniques to extinct species to be able to obtain at least fragments of DNA from very old bones. Over the years, its researchers have often been authors of researches on the subject presenting the results of the sequencing of a number of ancient hominins. The team that carried out this new research includes Matthias Meyer and Svante Pääbo, two of the most important paleogeneticists not only of their institute but of the whole world.

All the various advances allowed among other things to sequence a more or less high percentages of DNA of various Neanderthals but we’re still talking about a very small sample of a species that existed for many thousands of years and that left genetic traces in modern humans following various interbreedings. DNA degrades even under optimal conditions and the bones discovered can be in a state of conservation much less than optimal. The contamination by microbes or by the DNA of people who manipulated the bones is a further problem.

The researchers at the Max Planck Institute for Evolutionary Anthropology developed new methods to remove possible contaminations to obtain DNA belonging only to the bones examined. This allowed to obtain DNA from 5 individuals who lived in Belgium, France, Croatia and Russia between 39,000 and 47,000 years ago. This is a period close to the end of Neanderthals’ history so the sequenced genomes belong to some of the most recent individuals of that species whose remains were preserved.

The overall sample of Neanderthal genomes is small so adding those of 5 more individuals offers new clues to the history of that species. The possibility of comparing the various Neanderthal tenomes sequenced so far suggests, for example, that near the end of their history their populations moved, sometimes replacing each others, perhaps looking for greater luck in new territories.

The DNA of these 5 new individuals is closer to those of the Neanderthals that interbred with modern humans but none of them shows traces of hybridization. One possibility is that there was a flow of genes from Neanderthals to homo sapiens but not vice versa. The dynamics of the “encounters” between the two species are far from clear so any new information is very useful to understand more about that topic.

Janet Kelso, a member of the team that carried out this research, pointed out that it shows that the generation of genetic sequences of a vast number of individuals of archaic humans is now technically feasible and opens the possibility of studying the Neanderthal population in its geographical extension and through time. Basically, in the future we may perhaps really understand their evolution and maybe the reasons for their extinction.

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