Eastern pressure blade technology in west Scandinavia associated with WHG

New interesting preprint Ancient DNA from chewing gums connects material culture and genetics of Mesolithic hunter-gatherers in Scandinavia, by Kashuba et al. (2018).

Interesting excerpts (emphasis mine):

Mitochondrial genomes from all three individuals belong to the U5a2d haplogroup. (…) The mitochondrial U5a2d haplogroup is consistent with earlier published results for ancient individuals from Scandinavia, U5a being the most common within SHG. Of the 16 Mesolithic individuals from Scandinavia published prior to our study, seven belong to the U5a haplogroup, nine share the U2 and U4 haplogroups

We divided the SHG group into two groups: SHGa and SHGb (ancient individuals found in contemporary Norway and Sweden, respectively). We based this on both the geographical distribution and the previous studies demonstrating the close relation of SHGa to EHG group and SHGb to WHG group. To further explore the demography within the SHG group, we compared the ancestry of BLE individuals within SHGa and SHGb groups. This comparison revealed a high relative shared drift between BLE individuals and the SHGb group

scandinavia-hunter-gatherer-admixture
Admixture analysis showing the major mode for K=15. The figure represents 11 runs out of 20 replicates (Greedy algorithm ran with the Jaccard distance and a 0.97 similarity threshold)

The results from Huseby Kiev allow us to finally connect the SHG group with the eastern pressure blade technology. However, the higher genetic affinity between Huseby Kiev individuals and the WHG group challenges the earlier suggested tie between eastern technology and EHG genetics. Our results suggest either early cultural transmission, or a more complex course of events involving both non- and co-dependent cultural and genetic admixture.

huseby-kiev

Seeing how culture is indeed usually associated with the expansion of a certain population, especially at such an early date, I guess this similarity with WHG of incoming eastern peoples comes from an originally EHG population expanding into a mainly WHG area in the west (similar to what happens e.g. with Bell Beakers), or being replaced later by a WHG population which adopted the culture (similar to what happened with late Corded Ware populations in central-east Europe after the expansion of Bell Beakers).

Unlike later periods, it will always be difficult to judge such ancient population movements with few samples covering thousands of years… Probably specific Y-DNA haplogroups would help differentiate between both expanding populations from east and west.

Related

The preferred northwest passage to Scandinavia

Pontus Skoglund writes (and shares publicly) his perspective on early postglacial migrations of hunter-gatherers into Scandinavia, in Northwest Passage to Scandinavia (Nat. Ecol. Evol.): an initial migration from the south and a second coastal migration north of the Scandinavian ice sheet.

He sums up the recently published Open Access paper Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation, by Günther, Malmström , Svensson, Omrak, et al. PLoS Biol (2018) 16(1): e2003703, based on preprint at BioRxiv Genomics of Mesolithic Scandinavia reveal colonization routes and high-latitude adaptation (2017).

Abstract:

Scandinavia was one of the last geographic areas in Europe to become habitable for humans after the Last Glacial Maximum (LGM). However, the routes and genetic composition of these postglacial migrants remain unclear. We sequenced the genomes, up to 57× coverage, of seven hunter-gatherers excavated across Scandinavia and dated from 9,500–6,000 years before present (BP). Surprisingly, among the Scandinavian Mesolithic individuals, the genetic data display an east–west genetic gradient that opposes the pattern seen in other parts of Mesolithic Europe. Our results suggest two different early postglacial migrations into Scandinavia: initially from the south, and later, from the northeast. The latter followed the ice-free Norwegian north Atlantic coast, along which novel and advanced pressure-blade stone-tool techniques may have spread. These two groups met and mixed in Scandinavia, creating a genetically diverse population, which shows patterns of genetic adaptation to high latitude environments. These potential adaptations include high frequencies of low pigmentation variants and a gene region associated with physical performance, which shows strong continuity into modern-day northern Europeans.

The ice sheet distribution – which did not improve nuch for thousands of years – was clearly the greatest barrier for potential migrations in the region.

baltic-sea-10000-bc
Baltischer Süßwassersee Vorläufer der Ostsee vor 12.000 Jahren, by Juschki and Koyos at Wikipedia

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