A Northern European population history based on human genomes analysis

An international team of scientists, led by researchers from the Max Planck Institute for the Science of Human History, analyzed ancient human genomes from 38 northern Europeans dating from approximately 7,500 to 500 BCE.

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The study found that Scandinavia was initially settled via a southern and a northern route and that the arrival of agriculture in northern Europe was facilitated by movements of farmers and pastoralists into the region.

Northern Europe could be considered a late bloomer in some aspects of human history: initial settlement by hunter-gatherers occurred only about 11,000 years ago, after the retreat of the lingering ice sheets from the Pleistocene, and while agriculture was already widespread in Central Europe 7,000 years ago, this development reached Southern Scandinavia and the Eastern Baltic only millennia later.

Several recent studies of ancient human genomes have dealt with the prehistoric population movements that brought new technology and subsistence strategies into Europe, but how they impacted the very north of the continent has still been poorly understood.

For this study, the research team, which included scientists from Lithuania, Latvia, Estonia, Russia and Sweden, assembled genomic data from 38 ancient northern Europeans, from mobile hunter-gatherers of the Mesolithic (approximately 12,000 to 7,000 years ago) and the first Neolithic farmers in southern Sweden (approximately 6,000 to 5,300 years ago) to the metallurgists of the Late Bronze Age in the Eastern Baltic (approximately 1300 to 500 BCE). This allowed the researchers to uncover surprising aspects of the population dynamics of prehistoric northern Europe.

Two routes of settlement for Scandinavia

Previous analysis of ancient human genomes has revealed that two genetically differentiated groups of hunter-gatherers lived in Europe during the Mesolithic: the so-called Western Hunter-Gatherers excavated in locations from Iberia to Hungary, and the so-called Eastern Hunter-Gatherers excavated in Karelia in north-western Russia. Surprisingly, the results of the current study show that Mesolithic hunter-gatherers from Lithuania appear very similar to their Western neighbors, despite their geographic proximity to Russia. The ancestry of contemporary Scandinavian hunter-gatherers, on the other hand, was comprised from both Western and Eastern Hunter-Gatherers.

“Eastern Hunter-Gatherers were not present on the eastern Baltic coast, but a genetic component from them is present in Scandinavia. This suggests that the people carrying this genetic component took a northern route through Fennoscandia into the southern part of the Scandinavian peninsula. There they genetically mixed with Western Hunter-Gatherers who came from the South, and together they formed the Scandinavian Hunter-Gatherers,” explains Johannes Krause, Director of the Department of Archaeogenetics at the Max Planck Institute for the Science of Human History, and senior author of the study.

Agriculture and animal herding – cultural imports by incoming people

Large-scale farming first started in southern Scandinavia around 6,000 years ago, about one millennium after it was already common in Central Europe. In the Eastern Baltic, the inhabitants relied solely on hunting, gathering and fishing for another 1000 years. Although some have argued that the use of the new subsistence strategy was a local development by foragers, possibly adopting the practices of their farming neighbors, the genetic evidence uncovered in the present study tells a different story.

The earliest farmers in Sweden are not descended from Mesolithic Scandinavians, but show a genetic profile similar to that of Central European agriculturalists. Thus it appears that Central Europeans migrated to Scandinavia and brought farming technology with them.

Similarly, a near-total genetic turnover is seen in the Eastern Baltic with the advent of large-scale agro-pastoralism. While they did not mix genetically with Central European or Scandinavian farmers, beginning around 2,900 BCE the individuals in the Eastern Baltic derive large parts of their ancestry from nomadic pastoralists of the Pontic-Caspian steppe.

“Interestingly, we find an increase of local Eastern Baltic hunter-gatherer ancestry in this population at the onset of the Bronze Age,” states Alissa Mittnik of the Max Planck Institute for the Science of Human History, lead author of the study. “The local population was not completely replaced but coexisted and eventually mixed with the newcomers.”

(Source: https://www.archaeology.wiki/blog/2018/02/01/northern-european-population-history-revealed-ancient-human-genomes/)

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Abstract We sequenced the genomes of a ~7,000 year old farmer from Germany and eight ~8,000 year old hunter-gatherers from Luxembourg and Sweden. We analyzed these and other ancient genomes with 2,345 contemporary humans to show that most present Europeans derive from at least three highly differentiated populations: West European Hunter-Gatherers (WHG), who contributed ancestry to all Europeans but not to Near Easterners; Ancient North Eurasians (ANE) related to Upper Paleolithic Siberians, who contributed to both Europeans and Near Easterners; and Early European Farmers (EEF), who were mainly of Near Eastern origin but also harbored WHG-related ancestry. We model these populations’ deep relationships and show that EEF had ~44% ancestry from a “Basal Eurasian” population that split prior to the diversification of other non-African lineages.

(Source: “Ancient human genomes suggest three ancestral populations for present-day Europeans”, by I. Lazaridis et al.)

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Abstract Recent ancient DNA studies have revealed that the genetic history of modern Europeans was shaped by a series of migration and admixture events between deeply diverged groups. While these events are well described in Central and Southern Europe, genetic evidence from Northern Europe surrounding the Baltic Sea is still sparse. Here we report genome-wide DNA data from 24 ancient North Europeans ranging from ~7,500 to 200 calBCE spanning the transition from a hunter-gatherer to an agricultural lifestyle, as well as the adoption of bronze metallurgy. We show that Scandinavia was settled after the retreat of the glacial ice sheets from a southern and a northern route, and that the first Scandinavian Neolithic farmers derive their ancestry from Anatolia 1000 years earlier than previously demonstrated. The range of Western European Mesolithic hunter-gatherers extended to the east of the Baltic Sea, where these populations persisted without gene-flow from Central European farmers until around 2,900 calBCE when the arrival of steppe pastoralists introduced a major shift in economy and established wide-reaching networks of contact within the Corded Ware Complex.

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Recent genetic studies of ancient human genomes have revealed a complex population history of modern Europeans involving at least three major prehistoric migrations that were influenced by climatic conditions and availability of resources as well as the spread of technological and cultural innovations and possibly diseases. However, how and when they affected the populations of the very north of the European continent surrounding today’s Baltic Sea, where the archeological record shows a distinct history to that of Central and Southern Europe, has yet to be comprehensively studied on a genomic level.

The archeological record of the eastern Baltic and Scandinavia shows that settlement by mobile foragers started only after retreat of the glacial ice sheets around 11,000 years before present9. To the west and south, hunter-gatherers (Western Hunter-Gatherers or WHG) sharing a common genetic signature already occupied wide ranges of Europe from Iberia to Hungary for several millennia. They were shown to be descended from foragers appearing in Europe after around 14,000 years ago in a population turnover coinciding with the warming period of the Bølling-Allerød interstadial, possibly emerging from a southern refugium they inhabited since the Glacial Maximum and replacing preceding foraging populations. From further to the east in the territory of today’s Russia, remains of Mesolithic foragers (Eastern Hunter-gatherers or EHG) have been studied. They derived the majority of their ancestry, referred to as Ancient North Eurasian ancestry (ANE), from a population related to the Upper Paleolithic Mal’ta boy found in Siberia (MA1). Late Mesolithic foragers excavated in central Sweden, called Scandinavian Hunter-Gatherers (SHG) were modeled as admixed between WHG and EHG. Foraging groups along the eastern Baltic coast increasingly relied on marine resources during the 8th and 7th millennium calBCE and lived in more permanent settlements than their surrounding contemporaries.

The following Early Neolithic period, starting around 6,000 calibrated radiocarbon years before Common Era (calBCE), saw the transition from foraging to a sedentary agricultural lifestyle with the expansion of farmers out of Anatolia following the Danube and Mediterranean coast into Central and Southern Europe where they existed in parallel and admixed with local foragers for the following two millennia. This development reached South Scandinavia at around 4,000 calBCE with the farmers of the Funnel Beaker Culture (TRB; from German Trichterbecher) who gradually introduced cultivation of cereals and cattle rearing. At the transition to the northern Middle Neolithic, around 3,300 calBCE, an intensification of agriculture is seen in Denmark and western Central Sweden accompanied by the erection of megaliths and changes in pottery and lithic technology, while settlements in eastern Central Sweden increasingly concentrated along the coast and economy shifted toward marine resources such as fish and seal. A gradual change in material culture can be seen in the archeological assemblages of these coastal hunter-gatherers, known as the Pitted Ware Culture (PWC) with early pottery resembling the Funnel beakers in shape. Analysis of ancient genomes from PWC and megalithic Middle Neolithic TRB context in Central Sweden has shown that PWC individuals retain the genetic signature of Mesolithic hunter-gatherers while the TRB farmers’ ancestry can mainly be traced back to Central European farmers, albeit with substantial admixture from European hunter-gatherers.

The production and use of pottery, in Central and southern Europe often seen as part of the ‘Neolithic package’, was already common among foragers in Scandinavia during the preceding Mesolithic Ertebølle phase. Similarly in the eastern Baltic, where foraging continued to be the main form of subsistence until at least 4,000 calBCE, ceramics technology was adopted before agriculture. Recent genome wide data of hunter-gatherers from the Baltic Narva Culture revealed genetic continuity with the preceding Mesolithic inhabitants of the same region as well as influence from the more northern EHG.

The Late Neolithic is seen as a major transformative period in European prehistory, accompanied by changes in burial customs, technology and mode of subsistence as well as the creation of new cross-continental networks of contact seen in the emergence of the pan-European Corded Ware Complex (CWC, ca. 2,900 to 2,300 calBCE) in Central and northeastern Europe. Studies of ancient genomes have shown that CWC were genetically closely related to the pastoralist Yamnaya Culture from the Pontic-Caspian steppe, bringing with them a genetic component that was not present in Europe previously. Genomes from the CWC of Central Germany suggest that this new genetic component replaced around 75% of the local Middle Neolithic genetic substrate. Presumably this ‘steppe’ genetic component spread in the subsequent millennia of the Final Neolithic and Bronze Age throughout Europe and can be seen in today’s European populations in a decreasing northeast to southwest gradient. Intriguingly, modern eastern Baltics carry the most WHG ancestry of all Europeans1, supporting the theory of a remnant Mesolithic hunter-gatherer population in this region that left a lasting genetic impact on subsequent populations.

Here we genetically investigate these dynamics of population turnover and continuity at the northern fringe of prehistoric European occupation. In the most comprehensive ancient DNA study in Northern Europe to date, we present novel genome-wide data from 24 ancient individuals spanning 7,000 years of prehistory from the Baltics, Russia and Sweden. We show that the settlement of Scandinavia by hunter-gatherers likely took place via two different routes, and that the first introduction of farming was brought about by migration of Central European farmers around 4,000 calBCE. In the eastern Baltics, foraging remained the dominant economy, corresponding with a genetic continuity of the population up until around 3,000 calBCE, when we see the first major shift towards agro-pastoralism brought on by migrations from the Pontic steppe as opposed to Central Europe.

Conclusion With our analyses we support the pattern seen in the archeological record of continuity between the Mesolithic and Early Neolithic hunter-gatherer populations in the territory of modern Lithuania who appear genetically similar to Western hunter-gatherers. In contrast, contemporaneous hunter-gatherers from the more northern Latvia and Estonia were closer to Eastern hunter-gatherers. Networks of contact between the Baltic Sea and the river Volga could explain similarities seen in this region in pottery styles of hunter-gatherer groups although morphologically analogous ceramics could also have developed independently due to similar functionality. The situation appears differently in Scandinavia where a transition from foraging to agriculture in the Early Neolithic is carried by a demic diffusion from the south. Both the eastern Baltic and Scandinavia saw persistence of foraging throughout the Middle and Late Neolithic in populations that genetically largely descended from hunter-gatherer ancestors, as the resources of the Baltic Sea region, exploited through fishing and hunting, provided a beneficial environment for these groups and made it possible for them to maintain large population sizes without relying on crop cultivation.

We see a population movement into the regions surrounding the Baltic Sea with the Corded Ware Complex in the Late Neolithic that introduced animal husbandry to the eastern Baltic regions but did not completely replace local foraging societies. The presence of ancestry from the Pontic Steppe among Baltic CWC individuals without the Anatolian farming component must be due to a direct migration of steppe pastoralists that did not pick up this ancestry in Central Europe. This could lend support to a linguistic model that sees a branching of Balto-Slavic from a Proto-Indo-European homeland in the west Eurasian steppe. As farming ancestry however is found in later eastern Baltic individuals it is likely that considerable individual mobility and a network of contact throughout the range of the CWC facilitated its spread eastward, possibly through exogamous marriage practices. Conversely, the appearance of mitochondrial haplogroup U4 in the Central European Late Neolithic after millennia of absence could indicate female gene-flow from the eastern Baltic region, where this haplogroup was present at high frequency.

(Source: “The Genetic History of Northern Europe”, by Alissa Mittnik et al.)

αρχείο λήψης

Research-Selection for NovoScriptorium: Maximus E. Niles

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