The largest-ever study of almost 2,000 DNA samples carried out by Pompeu Fabra university in Barcelona has confirmed the ‘genetic singularity’ of the Basque population in Europe.

However, the research showed that this genetic difference only began to emerge 2,500 years ago in the Iron Age.

The study, published in the journal Current Biology, shows the Basque genetic differences are the result of centuries of isolation and inbreeding, potentially caused by unique Basque dialects which have no roots in any other living language anywhere in the world.

The particular Basque language, Euskera, might have limited Basques’ interactions with other communities, who couldn’t understand them.

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Researchers analysed the DNA of 190 people whose four grandparents were born in the same area. The results showed DNA pools are concentrated in regions according to the historical distribution of the various dialects of Basque.

The research team’s hypothesis is that the language was also an internal obstacle due to the existence of dialects that were not mutually intelligible.

The current standardised 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 said.

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The origin of the Basques has fascinated scientists since the 19th century, and the history of the population’s genetics has produced contradictory results.

In 2015, Mexican biologist Cristina Valdiosera of the University of Burgos showed that Basques are not as ancient as previously thought, marking their genetic divergence as starting 5,000 years ago.

In 2019, Íñigo Olalde’s team at Harvard University shortened it further to around 2,500 years ago, which was confirmed by the new study.