May 28, 2023

News 24a

News that matters

The first “family picture” of some Neanderthals. Researchers have solved a mystery

More than 50,000 years ago, in a cave in Siberia, there lived a community of Neanderthals made up of a single family, within which women migrated more than men.

A genetic study, published on Wednesday, outlines the contours of a “social organization” of these distant and missing cousins ​​of modern man, according to AFP, quoted by Agerpres.

The sequencing of the Neanderthal Man’s genome, carried out in 2010 by the Swede Svante Paabo, the recent laureate of the Nobel Prize for medicine, allowed the history of this extinct human line to be broadly traced, which populated the eastern part of Eurasia with 430,000 people, 40,000 years ago .

Thanks to archaeological excavations, it is now known that some of the Neanderthals buried their dead, produced elaborate tools and even ornaments, being far from the image of primitive brutes that was associated with them for a long time in the 20th century.

But scientists knew very little about their social structure. The genetic sequencing of an entire group of individuals, the largest ever performed on this hominid species, has removed some of this mystery.

The new discoveries were made in southern Siberia, Russia, a particularly fruitful region for ancient DNA research, as the cold helps preserve this fragile and precious clue from the distant past.

The genome of the Denisovan Man, another extinct human line, was taken from the same region, in the cave of the same name, recalls a press release published by the Max Planck Institute for Evolutionary Anthropology in Leipzig, where the research was carried out in the new study, published in Nature magazine.

A father and his daughter

100 kilometers away from the Denisova Cave are the Shaghirskaia and Okladnikov caves, occupied by Neanderthals about 54,000 years ago. Multiple vestiges have already been recovered there, from a single layer of sedimentary deposits, which led researchers to hypothesize that the cave dwellers lived in the two caves at approximately the same time.

To verify the new hypothesis, the DNA had to be allowed to speak, a task all the more delicate, as it was not about whole skeletons, but about teeth and bone fragments scattered inside the caves.

“First, we had to identify the number of individuals,” said paleogeneticist Stephane Peyregne, one of the study’s lead authors. His team used new techniques that allow ancient human DNA to be isolated – often “drowned” in microbial contamination – and captured.

The verdict: the human remains come from 13 Neanderthals (seven men and six women, including five children and young teenagers), 11 of whom lived in the Şaghirskaia cave.

In their mitochondrial DNA – transmitted only by the mother -, the researchers discovered the same genetic variant, a phenomenon known as heteroplasmy, which persisted only for a few generations.

The genes also revealed close parental ties: a father and his teenage daughter, a small boy and an adult woman who may have been his cousin, aunt or grandmother. These details represent direct evidence that those individuals belonged to the same family and that they lived in the same era.

Thanks to genetics, “we are today producing a concrete picture of what a Neanderthal community might have looked like,” said Benjamin Peter, who oversaw the research, along with Svante Paabo. “Neanderthals seem much more human to us now,” he added.

The analyzed group, genetically close to the Neanderthals of Western Europe, did not interbreed with other species – Homo sapiens and Denisova Man -, as the Neanderthals of other eras did.

“patrilocal” society

Their genetic diversity is, moreover, very weak, a sign of important inbreeding and of a life lived in a small group of 10-20 individuals, much smaller compared to the ancient communities of Homo sapiens.

“We are probably dealing with a very subdivided population,” which did not, however, live in a completely isolated manner, said Stephane Peygrene. Women tended to migrate from community to community to procreate, men stayed in their clan of origin. This “patrilocal” functioning, which also prevailed in Homo sapiens, is suggested by a genetic diversity of Y chromosomes (transmitted through the male line) much weaker than that of mitochondrial DNA, transmitted only by mothers.

Such an organization was already suggested after the discovery of similar fossils in El Sidron cave in Spain, but based on less diverse genetic material, said paleoanthropologist Antoine Balzeau, who was not involved in the new study.

“The new study represents a very interesting technical breakthrough for our research, even if we will have to compare the results with those obtained from other groups,” added Antoine Balzeau, researcher at the National Museum of Natural History in France.

Source link