Insights into the “isolation” of the Basques: mtDNA lineages from the historical site of Aldaieta (6th–7th centuries AD)

Abstract

We analyzed the hypervariable region I (HVR-I) sequence variability of the mitochondrial DNA (mtDNA) of individuals buried at Aldaieta (6th-7th centuries AD) in order to find out more about the biosocial implications of this cemetery. The results, fully authenticated by means of diverse criteria (analysis of duplicates, replication in an independent laboratory, quantification of target DNA, and sequencing and cloning of polymerase chain reaction products), suggest that Aldaieta largely consists of autochthonous individuals who shared common funereal customs with the late Ancient North Pyrenean cemeteries of Western Europe (the Reihengräberfelder), a cultural influence possibly accompanied by a certain genetic flow. Furthermore, the distribution of mtDNA lineages in the cemetery highlighted the existence of a significant number of family relationships, supporting the belief that it was a stable settlement and not a group that had haphazardly settled in the area. Finally, this paper stresses the importance of ancient DNA data for reconstructing the biological history of human populations, rendering it possible to verify certain hypotheses based solely on current population data. The presence at Aldaieta of an mtDNA lineage originating in Northwest Africa testifies to the existence of contact between the Iberian Peninsula and Northwest Africa prior to the Moorish occupation. Both this latter discovery and the high frequency of haplogroup J at the Aldaieta cemetery raise questions about the generally accepted belief that, since ancient times, the influence of other human groups has been very scarce in the Basque Country.

Mitochondrial lineage M1 traces an early human backflow to Africa

“…Again, this pattern is accurately repeated by the M1c and M1a distribution in the Iberian Peninsula, the northwest African M1 being more abundant in northern areas (56%) and the East African M1a in southern areas (85%) although, due to the small sample size, difference does not reach a significant level (p = 0.07). Additional support to the hypothesis of a prehistoric introduction are the recently detected presence of a Northwest African M1c lineage in a Basque cemetery dated to the 6 th –7 th centuries AD, prior to the Moorish occupation [42], and the ancestral phylogenetic position of another Basque M1d sequence (Fig. 1) that does not match any African sequence.…”

Using mitochondrial DNA to test the hypothesis of a European post-glacial human recolonization from the Franco-Cantabrian refuge

“…In spite of the severe isolation proposed to explain the genetic characteristics of the Basques, it seems that, as occurred for other populations of the Cantabrian Cornice Table S1). Although it is difficult to date the arrival of these lineages, the presence of an M1 haplotype in a Basque cemetery from the sixth to the seventh century AD, before the Arab occupation of Iberia (Alzualde et al, 2006), is in support of an old although small NorthAfrican influence on Northern Iberia. The rest of the haplotypes sampled are of clear Eurasian origin, and related to both Palaeolithic and Neolithic introductions.…”

Reconstructing the phylogeny of African mitochondrial DNA lineages in Slavs

“…34 Haplogroup M1 is rare in Iberia, but the presence of North African M1 mtDNA in the Basques remains that pre-date the Muslim invasion (eighth century) points to the prehistoric arrival of M1 lineages in Iberia. 38 Therefore, since most of the African lineages found in eastern European populations are present in West Africa, their migration to eastern Europe likely took them through Iberia.…”