The presence of haplogroup Z implies a contribution, albeit limited, to the Sami gene pool from Asia. The close relationship of Z1a lineages from Finns and Sami with those of the Volga-Ural again implicates that region as a probable source for Sami mitochondrial diversity. There is, however, a difference in the apparent ages of the different Sami haplogroups. The nucleotide diversity among Sami sequences for the three haplogroups studied here is very low. The ages of the variation for U5b1b1 and V among Swedish Sami are similar (5500 and 7600 YBP, respectively) but considerably older than for Z (2700 YBP). The surprisingly close link between haplogroup Z1a among Sami and the Volga-Ural sequences suggest that this haplogroup was brought in during the last 2–3000 YBP. Our data supports that a migration from Eastern Europe, in the vicinity of the Volga-Ural region, is the likely source for much of the Sami mtDNA diversity14 but indicates multiple migrations, the first being 6–7000 YBP and at least one additional migration 2–3000 YBP. Considering the similarity observed between Sami and Finnish mitochondrial lineages, this observation of multiple migration events would also support previous population genetic studies that have indicated dual origins of the Finnish people.37
European Journal of Human Genetics advance online publication 20 September 2006; doi: 10.1038/sj.ejhg.5201712
A recent genetic link between Sami and the Volga-Ural region of Russia
Max Ingman and Ulf Gyllensten
The genetic origin of the Sami is enigmatic and contributions from Continental Europe, Eastern Europe and Asia have been proposed. To address the evolutionary history of northern and southern Swedish Sami, we have studied their mtDNA haplogroup frequencies and complete mtDNA genome sequences. While the majority of mtDNA diversity in the northern Swedish, Norwegian and Finnish Sami is accounted for by haplogroups V and U5b1b1, the southern Swedish Sami have other haplogroups and a frequency distribution similar to that of the Continental European population. Stratification of the southern Sami on the basis of occupation indicates that this is the result of recent admixture with the Swedish population. The divergence time for the Sami haplogroup V sequences is 7600 YBP (years before present), and for U5b1b1, 5500 YBP amongst Sami and 6600 YBP amongst Sami and Finns. This suggests an arrival in the region soon after the retreat of the glacial ice, either by way of Continental Europe and/or the Volga-Ural region. Haplogroup Z is found at low frequency in the Sami and Northern Asian populations but is virtually absent in Europe. Several conserved substitutions group the Sami Z lineages strongly with those from Finland and the Volga-Ural region of Russia, but distinguish them from Northeast Asian representatives. This suggests that some Sami lineages shared a common ancestor with lineages from the Volga-Ural region as recently as 2700 years ago, indicative of a more recent contribution of people from the Volga-Ural region to the Sami population.