Basque ‘genetic singularity’ confirmed in largest-ever study

The new research shows that this difference only began to emerge 2,500 years ago as a result of centuries of isolation

Pensioners protesting in the Basque city of San Sebastián in January 2020.
Pensioners protesting in the Basque city of San Sebastián in January 2020.Javier Etxezarreta / EFE

The largest-ever study of almost 2,000 DNA samples carried out by researchers at Pompeu Fabra university (UPF) in Barcelona has confirmed the “genetic singularity” of the Basques in Europe. The investigation, however, found that this difference only began to emerge 2,500 years ago in the Iron Age. “Our analyses confirm that Basques were influenced by the major migration waves in Europe until the Iron Age, in a similar pattern as their surrounding populations,” the authors explain in the study published in the journal Current Biology.

The origin of the Basques has fascinated the scientific community since the 19th century. The French anthropologist Paul Broca snuck into a Basque cemetery one night in 1862 to steal skulls he wanted to study for their supposed genetic differences. Juan José Ibarretxe, premier of the Basque regional government until 2009, proclaimed that the Basque people “have existed for 7,000 years” to promote his vision of an independent Basque state. And the then-president of the Basque Nationalist Party (PNV), Xabier Arzalluz, claimed in 2000 that the Basques were “the oldest inhabitants of Europe,” with “their own roots” since prehistoric times.

Representation of the genetic structure in the historic Basque territory, where green represents Basque ancestry, and blue and red, the mix with neighboring communities.
Representation of the genetic structure in the historic Basque territory, where green represents Basque ancestry, and blue and red, the mix with neighboring communities. André Flores-Bello

Although Basque genetic differences are noticeable, the study shows this is the result of centuries of isolation and inbreeding potentially caused by unique Basque dialects that have no crossover with other European languages, or indeed any other living language today.

Their language limited their interaction with other communities, who couldn’t understand them. “Our analyses support the notion that the genetic uniqueness of Basques cannot be attributed to a different origin relative to other Iberian populations but instead to a reduced and irregular external gene flow since the Iron Age,” the study says. This means that “the Basques are not Martians,” jokes David Comas, lead author of the study and professor of Biological Anthropology at the UPF Department of Experimental and Health Sciences (DCEXS).

Some 7,000 years ago, groups that were genetically very similar to the Neolithic farmers and herders of Anatolia arrived in the Iberian peninsula. Their mixing with the native populations left groups with ancestry that was 80% Neolithic and 20% local Mesolithic, according to Basque geneticist Íñigo Olalde, whose team at Harvard University reconstructed the genomic history of the Iberian peninsula in 2019.

Subsequently, about 4,500 years ago, nomads who left the steppes of present-day Russia began to arrive in the Iberian peninsula, remixing the genes of the population into a balance of 40% foreign ancestry and 60% of what was already there. This is the common genetic substratum of all the peoples of the Iberian peninsula, including the Basques.

Researcher David Comas.
Researcher David Comas.UPF

Olalde affirms that Basques are genetically different from the rest of the Iberian Peninsula – but not that different. “Decades ago it was said that the Basques were the continuation of the hunter-gatherers and then it was seen that this was a total lie. Then it was said that they were a continuation of the Neolithic people who came later and that has also been shown to be false,” he explains.

This may be down to the peculiarity of the Basque language, Euskara, which has no roots in any other living language anywhere in the world. Comas’ group analyzed the DNA of 190 people whose four grandparents were born in the same area. The results show that even within the Basque Country itself, DNA pools are concentrated in small regions that coincide with the historical distribution of the various dialects of Basque. The hypothesis of Comas’ team is that the language was also an internal obstacle due to the existence of dialects that were not mutually intelligible. The current standardized Basque language, called Batua, was only developed and codified in the 1960s.

“Our results are compatible with Euskara as one of the main factors preventing major gene flow after the Iron Age and shaping the genetic panorama of the Basque region,” the study states.

The history of Basque genetics is littered with contradictory results. One of the co-authors of the new study, Jaume Bertranpetit, already led research in 2010 that came to the opposite conclusion: that Basques did not present a genetic uniqueness. “Undoubtedly, our previous work was not correct,” admits Bertranpetit. His group had used genetic analysis techniques that have now been overtaken by new technology.

Biologists and geneticists studying Basques are very reluctant to be drawn into political debates that make use of their work. “I am interested in historically isolated populations because, due to inbreeding, they have unique variants of diseases,” says Ana M. Aransay of Basque bioresearch center CIC bioGUNE. “There is a type of Parkinson’s disease that, in fact, has a name in Basque: dardarin [from the Basque word dardara which means trembling]. I have zero interest in politics,” she adds.

Mexican biologist Cristina Valdiosera of the University of Burgos had already shown by 2015 that the Basques are not as ancient as previously thought, marking their genetic divergence as starting around 5,000 years ago. Íñigo Olalde’s team at Harvard shortened it even further in 2019, and this was confirmed by the new study at around 2,000-2,500 years ago. “The rest of the Iberian populations begin to differentiate themselves from the Basque populations from the Iron Age onwards because they began to receive genetic influences from other populations, such as Muslims or the Romans. It is the Basques who are frozen in time,” says Valdiosera.

Comas, who has been researching Basque genetics for more than two decades, says the latest study can be interpreted in different ways. “The differences we observe can be magnified or minimized. The headline could be that Basques have a genetic singularity, that the Basques are different, or it could highlight the fact that the genetic substratum is the same as the rest of the Iberian peninsula, that the Basques are the same,” he jokes.

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