Genomic Diversity and Admixture Differs for Stone-Age Scandinavian Foragers and Farmers

Abstract

Prehistoric population structure associated with the transition to an agricultural lifestyle in Europe remains a contentious idea. Population-genomic data from 11 Scandinavian Stone Age human remains suggest that hunter-gatherers had lower genetic diversity than that of farmers. Despite their close geographical proximity, the genetic differentiation between the two Stone Age groups was greater than that observed among extant European populations. Additionally, the Scandinavian Neolithic farmers exhibited a greater degree of hunter-gatherer-related admixture than that of the Tyrolean Iceman, who also originated from a farming context. In contrast, Scandinavian hunter-gatherers displayed no significant evidence of introgression from farmers. Our findings suggest that Stone Age foraging groups were historically in low numbers, likely owing to oscillating living conditions or restricted carrying capacity, and that they were partially incorporated into expanding farming groups.

Tracing the genetic origin of Europe's first farmers reveals insights into their social organization

“…Y chromosome study of modern-day Europeans has suggested a post-LGM expansion from a Franco-Cantabrian refugium for clade I1, and southeast European refugium for I2a1 based on high divergence time estimates [58]. I2a has indeed been found in Mesolithic and Neolithic Central and North European hunter-gatherers [33,34,40,41], as well as in Neolithic remains of southwestern Europe [44,45]. Haplogroup I2a (and possibly I1) might represent a pre-farming legacy of the NRY variation in Europe, alongside the recently described pre-Neolithic C (M130) haplogroups in Russia and Spain [35,42].…”

“…Recent ancient DNA (aDNA) studies have provided direct insights into the mtDNA and nuclear genomic diversity of hunter-gatherers in Europe [28][29][30][31][32][33][34][35] and the Central European LBK [33,[36][37][38][39][40], describing genetic discontinuity between local foragers and early farmers [28,31,38,40]. Comparative analyses with present-day populations have revealed Near Eastern affinities of the mitochondrial LBK ancestry, supporting the demic diffusion model and population replacement at the beginning of the Neolithic period [38,39].…”

“…Ancient genomic studies have described the early farmers as genetically most similar to extant populations of southern Europe [31,33,40,41]. Y chromosome data from prehistoric Europeans is still scarce but relevant for our study (electronic supplementary material, dataset S20), including hunter-gatherers [33][34][35]40,42], and early farmers from Germany [38,40], eastern Hungary [41], Austria [43] and southwest Europe [40,44,45].…”

Ancient mitochondrial DNA from the northern fringe of the Neolithic farming expansion in Europe sheds light on the dispersion process

“…From Europe, data are available from nine Neolithic farmers [23,29,30], six Neolithic PWC hunter-gatherers [23,30], four Mesolithic hunter-gatherers [29][30][31] and the Tyrolean Iceman, a mummified body dated to the transition from the Neolithic to the Copper Age [32]. These techniques have also rendered possible the recovery of nuclear DNA data, from a range of archaeological materials [33][34][35].…”

“…To what extent this holds for Scandinavia is still unclear as only a limited number of early farmers have been genetically analysed [22,23,30]. As Scandinavia is a region at the geographical margin of early farming communities, and contained coexisting farmers and late hunter-gatherer communities [17,20,39], it holds a unique position to further highlight this question.…”