Basque People - Genetics

Genetics

Even before the development of modern genetics based on DNA sequencing, Basques were already noted for distinctive genetic patterns, such as possessing the highest global apportion of the Rh- blood type (35% phenotypically, 60% genetically). Additionally, the Basque population has virtually no B blood type, nor the related AB type.

Although they are genetically distinctive in some ways, the Basques are still very typically West European in terms of their Y-DNA and mtDNA sequences, and in terms of some other genetic loci. These same sequences are widespread throughout the western half of Europe, especially along the western fringe of the continent.

Specifically, studies of the Y-chromosome found that on their direct male lineages modern Basques have a common ancestry with other Western Europeans, namely the marked predominance of Haplogroup R1b.

The distinctiveness already noted by studies of 'classical markers', the subsequent discovery of frequency maximums of R1b in Basque populations, and the apparently "pre-Indo-European" nature of the Basque language resulted in a popular and long-held view that Basques are "living fossil" of the earliest modern humans which colonized Europe. Specifically, Y haplogroup R1b was deemed to be a Palaeolithic marker, highest in Basques, from when western Europe was repopulated after the Last Glacial Maximum, maybe 25,000 years ago.

As such, Basque populations were used as proxy representatives for the "Palaeolithic component" in admixture studies which tried to quantify the extent of Neolithic diffusions. Such studies concluded that the main components in the European genomes appear to derive from ancestors whose features were similar to those of modern Basques and Near Easterners, with average values greater than 35% for both these parental populations, regardless of whether molecular information is taken into account or not. The smallest degree of both Basque and Near Eastern admixture is found in Finland, whereas the highest values are, respectively, 70% "Basque" in Spain and roughly 60% "Near Eastern" in the Balkans.

However, this theory encountered inconsistencies even prior to most recent chronological re-evaluations. That R1b should be a Palaeolithic marker was an ad hoc assumption suggested by Semino et al. (2000) and then propagated by subsequent scholars without further analysis. Higher resolution STR analysis of R1b lineages from other western European populations (e.g. Italy or Britain) did not appear to derive from the Basque ones.

The majority of recent studies now propose that R1b spread through Europe from southwest Asia in the Neolithic period or later, between 4,000 to 8,000 years ago.

According to Myres and others (2010): "The coalescent estimate for the Y-STR network tree of 245 M269*+L23(xM412) chromosomes is 10 270±1680 years Before Present (BP)", which would coincide with the Neolithic Expansion from Anatolia. Another study done by Cruciani and others (2010) has also confirmed that there is a clear dichotomy between the Western-Eastern branches of R1b1b2. According to Cruciani and others. (2010):

The overall frequency pattern of theR1b1b2 sub-haplogroups here analyzed is compatible with several scenarios, including mutation surfing on the wave of advance of an expanding population and/or local bottlenecks and re-expansion from refuge areas. Preliminary time expansion estimates for haplogroups R1b1b2g (8.3ky; 95%CIs 5.8–10.9ky) and R1b1b2h (7.4ky; 95%CIs 5.3–10.2ky), based on 7STRs analyzed on 24 and 27 males respectively, are compatible with both Neolithic and post-glacial expansion/s within Europe. The majority (58.7%) of R1b1b2 chromosomes from Europe were found to be ancestral for both U106 and U152 (paragroup R1b1b2*) and showed a frequency cline from western to eastern Europe. Further studies are needed to refine the R1b1b2 phylogeny and fully disclose the micro-evolutionary events underlying the present frequency distribution of R1b1b2 sub-haplogroups.

Only Morelli et al. have recently attempted to defend an older, Palaeolithic chronology for R1b1b2(R-M269):

A recent network analysis of the R-M269 Y chromosome lineage has purportedly corroborated Neolithic expansion from Anatolia, the site of diffusion of agriculture. However, the data are still controversial and the analyses so far performed are prone to a number of biases. In the present study we show that the addition of a single marker, DYSA7.2, dramatically changes the shape of the R-M269 network into a topology showing a clear Western-Eastern dichotomy not consistent with a radial diffusion of people from the Middle East. We have also assessed other Y-chromosome haplogroups proposed to be markers of the Neolithic diffusion of farmers and compared their intra-lineage variation—defined by short tandem repeats (STRs)—in Anatolia and in Sardinia, the only Western population where these lineages are present at appreciable frequencies and where there is substantial archaeological and genetic evidence of pre-Neolithic human occupation. The data indicate that Sardinia does not contain a subset of the variability present in Anatolia and that the shared variability between these populations is best explained by an earlier, pre-Neolithic dispersal of haplogroups from a common ancestral gene pool. Overall, these results are consistent with the cultural diffusion and do not support the demic model of agriculture diffusion.

Autosomal genetic studies, on the one hand, confirm that Basques have a very close relationship with other Europeans, especially with rest of Spaniards, who have a common genetic identity of over 70% with Basques. However, a study done in May, 2010 has shown homogeneity of Spanish and French Basques, and confirmed their genomic distinctiveness from other European populations.

Finally, several ancient DNA samples have been recovered and amplified from Palaeolithic sites in the Basque region. The collection of mtDNA haplogroups sampled there differed significantly compared to their modern frequencies, leading the authors to conclude that there is "discontinuity" between ancient and modern Basques.

Thus, whilst Basques (like all Europeans) harbour some very archaic lineages (such as mtDNA Hg U8a), they are not of "undiluted Palaeolithic ancestry", nor are they ancestral to large parts of western Europe. Rather, their genetic distinctiveness is a result of centuries of low population size, genetic drift and endogamy.

The principal conclusion is that the male Basques living today have rather recent roots of less than four thousand years, contrary to legend that proposes they lived some 30,000 years ago. Despite the ancient language, it is very likely that the present day Basques represent a rather recent Iberian population, in terms of DNA genealogy.

In 1920, H. G. Wells referred to the Mediterranean race as the Iberian race. He regarded it as a fourth subrace of the Caucasian race, along with the Aryan, Semitic, and Hamitic subraces. He stated that the main ethnic group that most purely represented the racial stock of the Iberian race was the Basques, and that the Basques were the descendants of the Cro-Magnons. In 1994, in his book The History and Geography of Human Genes, population geneticist L. Luca Cavalli-Sforza stated that "there is support from many sides" for the hypothesis that the Basques are the descendants of the original Cro-Magnons.