This is a fairly interesting study that paints a picture of continuity of genetic structure among Basques since pre-Roman times. I am not sufficiently familiar with either Basque history or geography to comment on this in detail, but the central conclusion that Basques differ from their neighbors in being more isolated and less cosmopolitan is something that I have also noticed in my own experiments (see for example the K12b population portraits, contrasting French_Basque and Pais_Vasco_1KG with other Iberian/French populations).
For those who know more, does the following scheme make sense?
Y-haplogroup frequencies, showing a preponderance of R-M269 related lineages and a strong showing of the the I-M26 lineage are shown below. The latter links Basques with Sardinians, as well as probably with Neolithic France.
Codes (from the paper): BIG, Bigorre; BEA, Béarn; CHA, Chalosse; ZMI, Lapurdi/Baztan; NLA,Lapurdi Nafarroa; SOU, Zuberoa; RON, Roncal and Salazar valleys; NCO, CentralWestern Nafarroa; NNO, North Western Nafarroa; GUI, Gipuzkoa; GSO, SouthWestern Gipuzkoa; ALA, Araba; BBA, Bizkaia; BOC, Western Bizkaia; CAN,Cantabria; BUR, Burgos; RIO, La Rioja; NAR, North Aragon.
The picture of continuity is further strengthened by ancient Basque Y-chromosomes, showing the same picture of R1b-majority/I minority as today. What we really need now is to bridge the gap between late antiquity and the Neolithic, and beyond to better understand the temporal sequence of settlement.
Mol Biol Evol (2012)doi: 10.1093/molbev/mss091
Evidence of pre-Roman tribal genetic structure in Basques from uniparentally inherited markers
Begoña Martínez-Cruz et al.
Basque people have received considerable attention from anthropologists, geneticists and linguists during the last century due to the singularity of their language and to other cultural and biological characteristics. Despite the multidisciplinary efforts performed to address the questions of the origin, uniqueness and heterogeneity of Basques, the genetic studies performed up to now have suffered from a weak study-design where populations are not analyzed in an adequate geographic and population context. To address the former questions and to overcome these design limitations, we have analyzed the uniparentally inherited markers (Y chromosome and mitochondrial DNA) of ∼900 individuals from 18 populations, including those where Basque is currently spoken and populations from adjacent regions where Basque might have been spoken in historical times. Our results indicate that Basque-speaking populations fall within the genetic Western European gene pool and they are similar to geographically surrounding non-Basque populations, and also that their genetic uniqueness is based on a lower amount of external influences compared to other Iberians and French populations. Our data suggest that the genetic heterogeneity and structure observed in the Basque region results from pre-Roman tribal structure related to geography and might be linked to the increased complexity of emerging societies during the Bronze Age. The rough overlap of the pre-Roman tribe location and the current dialect limits supports the notion that the environmental diversity in the region has played a recurrent role in cultural differentiation and ethnogenesis at different time periods.