One of the first posts on this blog relating to archaeogenetics involved an essay by me involving reflections on the fact that a particular Y chromosomal haplogroup, N1c (N3a now), had a peculiar distribution which ranged from Siberia to Finland. The argument, at the time, was whether it was a lineage which moved east to west (as suggested by the decline of microsatellite diversity in that direction), or whether it moved west to east (as was suggested by the frequency, which was highest in parts of Uralic Europe).
Today we know the general outline of the answer. The N1c lineage seems to have moved westward along the forest-tundra fringe, along with Uralic peoples in general. Genome-wide evidence shows minor but significant affinities with Siberian people among many European Uralic groups, including the Finns, and to a lesser extent Estonians. Though the genome-wide fraction is small in Finns, 5% or less, because this minor component is so genetically different from the generic Northern European ancestry of this group, it shifts Finns off the normal dimensions of variation for Europeans (in addition to the fact that many Finns have been subject to bottlenecks). The fraction is higher in the Sami, and lower in the Estonians.
Additionally, ancient DNA suggests that the arrival of this ‘eastern’ Uralic mediated ancestry seems to date to the early Iron Age. The hypothesis that the Finnic languages were primal to Baltic Europe, is on shaky ground which has cracked open. Rather, the circumstantial evidence is that Finnic languages replaced Indo-European dialects.
A new paper from Estonia as some more detail to the general outline, as well as highlighting some aspects of adaptation. The Arrival of Siberian Ancestry Connecting the Eastern Baltic to Uralic Speakers further East:
In this study, we compare the genetic ancestry of individuals from two as yet genetically unstudied cultural traditions in Estonia in the context of available modern and ancient datasets: 15 from the Late Bronze Age stone-cist graves (1200–400 BC) (EstBA) and 6 from the Pre-Roman Iron Age tarand cemeteries (800/500 BC–50 AD) (EstIA). We also included 5 Pre-Roman to Roman Iron Age Ingrian (500 BC–450 AD) (IngIA) and 7 Middle Age Estonian (1200–1600 AD) (EstMA) individuals to build a dataset for studying the demographic history of the northern parts of the Eastern Baltic from the earliest layer of Mesolithic to modern times. Our findings are consistent with EstBA receiving gene flow from regions with strong Western hunter-gatherer (WHG) affinities and EstIA from populations related to modern Siberians. The latter inference is in accordance with Y chromosome (chrY) distributions in present day populations of the Eastern Baltic, as well as patterns of autosomal variation in the majority of the westernmost Uralic speakers [1, 2, 3, 4, 5]. This ancestry reached the coasts of the Baltic Sea no later than the mid-first millennium BC; i.e., in the same time window as the diversification of west Uralic (Finnic) languages [6]. Furthermore, phenotypic traits often associated with modern Northern Europeans, like light eyes, hair, and skin, as well as lactose tolerance, can be traced back to the Bronze Age in the Eastern Baltic.