Biology subjects

Geary, P. J.

Publications and source records attributed to Geary, P. J..

4 recordsLinked to original sources

bioRxiv2025

The shifting dynamics of ancestry and culture at a post-Roman crossroads

The collapse of the western Roman Empire in the 5th century created a period of geopolitical upheaval, driven by Barbarians dispersing into the former Empire and reshaping post-Roman communities. While there is now evidence for a major genetic impact of these migrations into specific regions of Europe, it is unknown whether these changes in ancestry were uniform across the continent. We investigate present-day Slovenia, a crucial crossroad connecting the Roman East and West and the gate to Italy during the Langobard invasion. We conducted paleogenomic and isotopic analyses of 410 individuals from 21 sites across Slovenia and Cividale (Italy), establishing a longitudinal transect, spanning eight centuries. During Late Antiquity, despite changes in burial artifacts, kinship practices, and settlement structures reflecting a shift in culture, we find high levels of genetic continuity with the local Late Roman population and reduced mobility. However, demographic turnover began during the 8th century, when communities with northeastern European ancestry and distinct cultural practices entered the region, gradually advancing westward over the span of three centuries, replacing the local populations. This shows that cultural change in post-Roman Europe could be decoupled from genetic change in transit zones, demonstrating a dynamic spatiotemporal process across the continent.

genetics↗

bioRxiv2025

Unveiling the complexity of post-Roman polity formation using ancient DNA

The transformation of the Roman world (4th-9th centuries CE) culminating in the dissolution of the Western Roman Empire in the 5th century marked a fundamental transition in European history. "Barbarian" groups and Roman provincial societies merged into enduring political frameworks in some places but not in others. Key questions persist regarding the regionally specific nature of this transformation. Here, we present one of the most densely sampled early medieval datasets to date, enabling the reconstruction of a post-Roman polity at an unprecedented micro-regional resolution. Our integrated genetic and archaeological analysis of two Roman-period (n=68) and five post-Roman (n=246) sites from the Little Hungarian Plain, a former Roman frontier region, reveals a significant increase in Northern European genetic ancestry, likely reflecting a large-scale population movement into the region. Moreover, while all post-Roman sites, dated to the time of the Langobard Kingdom, share similar genetic profiles, burial practices, and material culture, they display distinct patterns of social organization, especially regarding the role that biological relatedness played in each community. Our results suggest that distinct social hierarchies might have existed between sites, and their intensive connectivity probably formed the basis for regional-level organisation within the post-Roman polity. Our study provides a framework for investigating how new polities take shape after the collapse of major political systems. Applied more broadly, this approach can deepen our understanding of societal transformation across early medieval Europe and beyond, offering a richer and more nuanced view of the human past than ever before.

evolutionary biology↗

bioRxiv2022

Investigating community formation through dense spatial and temporal sampling of 5-6th century cemeteries in Pannonia

As the collapse of the Western Roman Empire accelerated during the 4th and 5th centuries, arriving "barbarian" groups began to establish new communities in the border provinces of the declining (and eventually former) empire. This was a time of significant cultural and political change throughout not only these border regions but Europe as a whole.1,2 To better understand post-Roman community formation in one of these key frontier zones after the collapse of the Hunnic movement, we generated new paleogenomic data for a set of 38 burials from a time series of three 5th century cemeteries3-5 at Lake Balaton, Hungary. We utilized a comprehensive sampling approach to characterize these cemeteries along with data from 38 additional burials from a previously published mid-6th century site6 and analyzed them alongside data from over 550 penecontemporaneous individuals7-19. The range of genetic diversity in all four of these local burial communities is extensive and wider ranging than penecontemporaneous Europeans sequenced to date. Despite many commonalities in burial representation and demography, we find that there were substantial differences in genetic ancestry between the sites. We detect evidence of northern European gene flow into the Lake Balaton region. Additionally, we observe a statistically significant association between dress artefacts and genetic ancestry among 5th century genetically female burials. Our analysis shows that the formation of early Medieval communities was a multifarious process even at a local level, consisting of genetically heterogeneous groups.

genetics↗

bioRxiv2018

Understanding 6th-Century Barbarian Social Organization and Migration through Paleogenomics

ABSTARCTDespite centuries of research, much about the barbarian migrations that took place between the fourth and sixth centuries in Europe remains hotly debated. To better understand this key era that marks the dawn of modern European societies, we obtained ancient genomic DNA from 63 samples from two cemeteries (from Hungary and Northern Italy) that have been previously associated with the Longobards, a barbarian people that ruled large parts of Italy for over 200 years after invading from Pannonia in 568 CE. Our dense cemetery-based sampling revealed that each cemetery was primarily organized around one large pedigree, suggesting that biological relationships played an important role in these early Medieval societies. Moreover, we identified genetic structure in each cemetery involving at least two groups with different ancestry that were very distinct in terms of their funerary customs. Finally, our data was consistent with the proposed long-distance migration from Pannonia to Northern Italy.

genetics↗