Russian invaders finished with the Iberian population of the Neolithic

Russian invaders finished with the Iberian population of the Neolithic


Hosted between two continents, the Iberian Peninsula has been the place of passage for a large number of towns that have left their mark in the last 8,000 years. Now him greater study of DNA made to date reveals the extent to which some of these people managed to mold the Iberian genome.

The research, published in Science, has been coordinated by David Reich and Carles Lalueza-Fox, geneticists from the Harvard Medical School and the Institute of Evolutionary Biology (IBE), respectively, and carried out by 111 scientists from the United States and Europe, who have analyzed 403 old genomes of the Iberian Peninsula, which is one of the most complete data collections in Europe.

In addition, 271 genomes of the study had not been previously analyzed and most are from the last 4,000 years, a period little studied until now with ancient DNA and that provides unpublished information from the Bronze Age to the Middle Ages.

The study confirms that the genome of the inhabitants of the Iberian Peninsula is the result of "a superposition of layers produced over thousands of years for different migrations, some of them relatively recent like that of the Romans or the Muslims ", explains Efe Carles Lalueza-Fox.

One of the most surprising and unprecedented conclusions of the study refers to replacement (almost total) of the Iberian paternal lineages that took place between 2,500 and 2,000 a.C.

In that period of transition between the Copper Age and the Bronze Age, for some 500 years tumultuous social events took place that "we do not know how they happened but that clearly they replaced the Iberian paternal lineages by a paternal lineage of steppe origin, which even today is still the most common in the Iberian Peninsula, "says Lalueza-Fox.

Genetic analysis reveals that between 2,500 and 2,000 BC, the typically Iberian population of the Neolithic coexisted with the descendants of steppe populations that 500 years earlier had spread rapidly throughout Europe from the Russian steppe.

"It was a long colonization, of about 500 years", which left its imprint on the genetic composition of the population of the Iberian Peninsula that, during the Bronze Age, had lost about 40% of its genetic ancestry and 100% of the Iberian paternal lineages, which were replaced by the steppe (which lasts today).

Two of the genomes studied at work illustrate that moment in history.

"They are the remains of a couple buried in Castillejo del Bonete (Ciudad Real). Man has very recent ancestors from these new human groups that came to the Peninsula, while the woman is of Iberian ancestry. We also know that she had a maritime diet and that she came from the coast and, despite these differences, they are buried together. It is a very illustrative example of coexistence, "says Lalueza-Fox.

And one of the most interesting aspects of DNA is that "it tells what events happened and when, but not how." There are several hypotheses that can explain what happened but other disciplines such as archeology or anthropology are needed to understand what happened ", warns Efe Íñigo Olalde, Harvard geneticist and first author of the work.

"The results of our study could be compatible with a violent situation", similar to a genocide," but in the archaeological record there is no evidence of such violence. "

"Another possibility could be that, due to a strong social stratification, local women preferred men from foreign clans" and that they had "greater reproductive success than local ones", but the genetic data alone will never reveal the full story insists Olalde.

The study also reveals that in the Neolithic there was another genetic replacement in the Iberian population triggered by the arrival of farmers from Anatolia (now Turkey), which replaced the culture of hunter-gatherers at the end of the Mesolithic (from 8,000 BC to 5,500 BC)

The Neolithic populations mixed with the Iberian population, which had an even greater demographic impact than the one that would take place some 3,000 years later, in the Bronze Age, but "although they replaced 80 percent of the Iberian genome, the impact was not as strong in strictly paternal lineages, "says Olalde.

The study also reveals exceptional cases that show that there was an interaction with North Africa, such as an individual with a 100% North African ancestry, that in 2,300 BC was buried in the Camino de las Yeseras (Madrid), or that of a woman, with 25% African ancestry, who died in the area of ​​Loma del Puerco (Cádiz).

These are cases that did not modify at all the ancestrality of the Iberian population but show that there were sporadic and early contacts between populations and, above all, they are "incredible and anonymous individual stories of people who will never know who they were or what they did but who had an exceptional life trajectory for the time", underlines Lalueza-Fox.

Similarly, in a Visigothic site, in Gerona, "two individuals with ancestrality from the far east of Europe and with an Asian mitochondrial DNA" were found, and in Ampurias other individuals with Greek ancestry, all with a "vital trajectory" incredible ", taking into account that they or their closest relatives were born in the VI and VII centuries in points very far from the Peninsula but ended up buried in it.

The investigation concludes that the genetics of the Basques -a people whose genetic ancestry has been debated a lot-, has not changed practically since the Iron Age.

Researchers have determined that they have not received so much genetic influence from the peoples that have passed through the Iberian Peninsula in the last 2,500 years, such as Punic, Roman, Greek or Muslim, which would explain why Euskera is the only one pre-Roman language that lasts today.

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