Genetic study Historic Genomes Uncover Demographic Shifts and Kinship Structures in Post-Roman Central Europe

[Tautalus]

Summary

Many European towns and villages trace their origins to Early Medieval foundations. In former Roman territories, their emergence has traditionally been linked to mass migrations from outside the Roman Empire. However, recent studies have emphasised local continuity with some individual-level mobility. We generated and analysed 248 historic genomes from Late Roman (3rd and 4th century CE) and Early Medieval (5th–8th century CE) burial sites in southern Germany, comparing them to over 2,500 contemporary and Iron Age genomes in addition to 1,344 modern-day genomes from Germany, Italy and Great-Britain. Despite small inferred Early Medieval period community sizes, genetic diversity exceeded that of modern German cities. In the Altheim graveyard, established in the 5th century by a group of Northern European descent, we inferred a demographic shift in the 6th century with the integration of newcomers with ancestry typical of a nearby Roman military camp, likely as a result of the collapse of Roman state structures. We reconstructed multigenerational pedigrees and, using a novel approach to infer ancestry of unsampled relatives, inferred immediate intermarriage between incoming and local groups, with a distinct tendency for men from former Roman background marrying women of northern descent. Burial proximity correlates strongly with kinship, in some cases spanning six generations. These communities were organized around small family units, exhibited loosely patrilineal or bilateral descent patterns, practiced reproductive monogamy, and avoided close-kin marriages. Such practices reflect broader transformations in family structures that began during the Late Roman period, were transferred to small agrarian societies in the Early Medieval period, and continued to shape European societies. By the 7th century, ongoing admixture had shaped genetic diversity patterns into those resembling Central Europe today.
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Historic Genomes Uncover Demographic Shifts and Kinship Structures in Post-Roman Central Europe

Many European towns and villages trace their origins to Early Medieval foundations. In former Roman territories, their emergence has traditionally been linked to mass migrations from outside the Roman Empire. However, recent studies have emphasised local continuity with some individual-level...

www.biorxiv.org

 

[Riverman]

Unfortunately no supplementary material yet. Apparently, there was a wide ranging admixture from the Roman settlements into the Germanic tribals at the end of the Roman Empire. The similarities of the South Eastern-like population element point to the Carpathian basin samples, but they don't think there was a major pulse migration due to local cultural continuity. However, only genetics can prove that, especially in the Roman case, in which new migrants quickly adapted and adopted.
Suprisingly, they also point to a lot of instance of SEE males mixing with Germanic females - also in the Germanic communities. The context of this pattern is worth to be investigated and I hope the raw data and supps get published soon. Obviously, I expect some E-V13 males to pop up, even though the core Bavarian zone in modern times is probably less of a centre for that haplogroup than say the Rhenish or Franconian area within the German speaking sphere.

 

[Tautalus]

The paper conveys a more nuanced version of the Migration Period, at least in this region of southern Germany. There is no simplistic view of the Migration Period as a time of widespread upheaval caused by large-scale migrations of "barbarian" tribes. Rather than describing a massive, single event of invasion or displacement by Germanic tribes, it emphasizes the integration and local continuity of communities of Northern European-descended populations who had already lived on the borderlands of the Empire or even in the Empire itself prior to its fall. These groups lived under Roman influence for generations and adopted aspects of Roman culture, their presence influenced the demographic and social transitions seen in post-Roman Central Europe.

By the end of the 5th century, the military, political, and economic structures of the Roman Empire had disintegrated, which served as a facilitator for the significant demographic transition that occurred in the 6th century. The paper refers the integration of individuals with south-eastern Europe ancestry from nearby Roman towns and military camps into communities of Northern European descent. It notes that intermarriage between these groups was common, with a tendency for Roman-background males to marry females of Northern descent. If this process was replicated in other areas, it would have contributed to many y haplogroups present in southeastern Europe, like some clades of E and J2, infiltrating into Central Europe.​

 

[Hallstatt]

Rather than describing a massive, single event of invasion or displacement by Germanic tribes, it emphasizes the integration and local continuity of communities of Northern European-descended populations who had already lived on the borderlands of the Empire or even in the Empire itself prior to its fall. These groups lived under Roman influence for generations and adopted aspects of Roman culture, their presence influenced the demographic and social transitions seen in post-Roman Central Europe.
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But does it not say that the pre IA-SE profile was IA-NC (Iron Age North-Central Europe) What do they mean by Central Europe? Germanics mixed with Celts, or North Germanics mixed with Central Europe Germanics (Marcomanni, Quadi etc)?

 

[Tautalus]

But does it not say that the pre IA-SE profile was IA-NC (Iron Age North-Central Europe) What do they mean by Central Europe? Germanics mixed with Celts, or North Germanics mixed with Central Europe Germanics (Marcomanni, Quadi etc)?

Good question, the paper is not clear, they say they used various Iron Age populations to model the ancestries of the samples studied. That information must be in the supplementary information, but was not yet available in Biorxiv.
The IA-NC profile they refer to must contain some genetic variation, probably with some Celtic influence. There must have been some sort of admixture in the studied area.
But I think that when they talk about that profile, they are essentially referring to Northern Europe Germanic ancestry.
By the Late Roman period, the population of southern Germany must have been predominantly Germanic, though there were still remnants of Celtic influence. I think that the Celts had largely retreated westward to Gaul due to the steady expansion of Germanic tribes, such as the Suebi and Alemanni, who had moved into the region over the previous centuries. Due to the southward expansion of Germanic tribes, with the Romans increasingly reliance on Germanic recruits and with the increasing Germanic population settling on Roman lands, the ethnic composition of that area must have changed during the Late Roman period.

Barbarian migrations and invasions​

 

[Vitruvius]

The idea that the Germanic languages arrived in small but continuous waves of settlement and integration as opposed to large sweeping upheavals or replacements seems the much more likely case to me. I've never considered Germanic speakers to be some sort of pure or near pure population replacement of local elements with Scandinavian newcomers. The sample size in this study is very large and should give us a pretty good idea as to what was going on.

 

[Tautalus]

I've never considered Germanic speakers to be some sort of pure or near pure population replacement of local elements with Scandinavian newcomers.

There are studies that say otherwise, specifically about southern Germany, like this one : Evidence for dynastic succession among early Celtic elites in Central Europe.

“In southern Germany (here Baden-Württemberg and Bavaria) the northern European influx broadens to a major genetic turnover between the Iron Age and the Early Middle Ages (Fig. 4c and Supplementary Note 5). It is illustrated by a sharp decrease of EEF ancestry and a substantial resurgence of Steppe-related ancestry together with a rediversification of the gene pool (Supplementary Figs. 4.4, 4.5 and 5.2). While the Hallstatt population showed highest genetic affinity to present-day French, Spanish and Belgians, the early medieval (Alemannic and Bavarian) populations of southern Germany exhibit closest resemblance to present-day Danish, northern Germans,Dutch and Scandinavians (Supplementary Fig. 5.4) and are genetically indistinguishable from Iron Age and Medieval groups in northern Germany and Scandinavia (Supplementary Table 2.10). We argue that this is the result of a major genetic influx from those regions”.​

We can argue about what “genetically indistinguishable” means, what the degrees of genetic distance or differentiation between these populations are, but even if there was some admixture with local Celtic populations in the area, most of the ancestry of the early medieval populations of southern Germany come from northern Germany and Scandinavia.

 

[Vitruvius]

Deleted

 

[Vitruvius]

There are studies that say otherwise, specifically about southern Germany, like this one : Evidence for dynastic succession among early Celtic elites in Central Europe.

“In southern Germany (here Baden-Württemberg and Bavaria) the northern European influx broadens to a major genetic turnover between the Iron Age and the Early Middle Ages (Fig. 4c and Supplementary Note 5). It is illustrated by a sharp decrease of EEF ancestry and a substantial resurgence of Steppe-related ancestry together with a rediversification of the gene pool (Supplementary Figs. 4.4, 4.5 and 5.2). While the Hallstatt population showed highest genetic affinity to present-day French, Spanish and Belgians, the early medieval (Alemannic and Bavarian) populations of southern Germany exhibit closest resemblance to present-day Danish, northern Germans,Dutch and Scandinavians (Supplementary Fig. 5.4) and are genetically indistinguishable from Iron Age and Medieval groups in northern Germany and Scandinavia (Supplementary Table 2.10). We argue that this is the result of a major genetic influx from those regions”.​

We can argue about what “genetically indistinguishable” means, what the degrees of genetic distance or differentiation between these populations are, but even if there was some admixture with local Celtic populations in the area, most of the ancestry of the early medieval populations of southern Germany come from northern Germany and Scandinavia.

Looking at this now, you seem to be right. So it would seem to appear we have two different studies giving two different conclusions as to how this transition occurred.