Isolation and limited gene flows with neighbouring populations are the reasons behind the "genetic uniqueness" of people in Spain's Basque region, a new study has concluded.
It said people there had "genetic continuity" that stretches back to the Iron Age (500-332 BC).
The study is believed to be the most comprehensive geographic sampling to date of the Basque population, with "over 600,000 genetic markers throughout the genome for each individual".
Professor David Comas, who led the research, said the study found no "influences from North Africa", which, on the contrary, "are appreciated in most populations of the Iberian Peninsula", nor did it find traces of Roman migrations.
The Basque language, the Euskara, was a factor that encouraged the region's isolation, acting as a barrier against contacts with other European populations.
Speaking to Euronews, Professor Comas, from Pompeu Fabra University in Barcelona, said that Basques are "genetically different", though "not so different as it has sometimes been claimed".
"Europe is a very homogeneous continent in genetic terms", but, he adds, "there are some populations that stand out, such as the Finns or the Sardinians and also the Basques".
"This is however not due to different origins", but mainly due to isolation, with limited gene-flow from external populations, he added.
Watch the interview with Professor Comas in the video player, above.