Ancient DNA reveals human migration patterns in the first millennium AD

Researchers at the Francis Crick Institute have made breakthrough discoveries about human migration patterns across Europe during the first millennium AD. 

Using advanced DNA analysis techniques, they traced the movement of populations across the continent, offering new insights into how ancient groups interacted and reshaped the genetic landscape of Europe. 

The findings, published in the journal Nature, highlight a dynamic era of migration and cultural evolution that shaped the foundation of modern European societies.

A new lens for genetic analysis

At the heart of the research is Twigstats, a new analytical method that allows scientists to identify subtle genetic differences between populations that are otherwise very similar. 

Traditional tools have been effective in studying major population shifts, such as those between hunter-gatherers and early farmers, but they often miss finer-scale changes.

Twigstats overcomes this limitation, offering a sharper lens to examine the genetic complexities of historical migrations.

Leo Speidel, the study’s first author, emphasized the significance of this innovation. “Twigstats allows us to see what we couldn’t before, in this case migrations all across Europe originating in the north of Europe in the Iron Age, and then back into Scandinavia before the Viking Age.”

By applying this tool to over 1,500 genomes from individuals who lived between the years 1 and 1000 AD, the researchers reconstructed migration patterns spanning key historical periods, including the Iron Age, the fall of the Roman Empire, the early medieval Migration Period, and the Viking Age.

Human migrations into Southern Europe 

Historical records from the Roman Empire mention conflicts with Germanic groups beyond its borders.

The genetic evidence uncovered by Twigstats supports these accounts, revealing waves of migration from Northern Germany and Scandinavia into Southern Europe during the early first millennium.

This migration left its mark on the genetic makeup of regions such as southern Germany, Italy, Poland, Slovakia, and southern Britain. 

In some cases, individuals carried exclusively Scandinavian-like ancestry, indicating significant movement of people from the north. 

These findings align with the linguistic evolution of Germanic languages, with one branch remaining in Scandinavia, another becoming extinct, and the third forming the basis of modern German and English.

Scandinavian influence in pre-Viking Britain

An unexpected discovery was the presence of Scandinavian ancestry in Britain centuries before the Viking Age. 

The researchers identified a second-to-fourth-century individual from York who exhibited 25% early Iron Age Scandinavian ancestry. 

This predates the Anglo-Saxon and Viking migrations traditionally associated with Scandinavian influence in Britain. The finding highlights the long-standing connections between Scandinavia and the British Isles.

Human migrations into Scandinavia

The study also uncovered a later migration wave into Scandinavia between 300 and 800 AD, preceding the Viking Age.

Genetic evidence shows that many individuals from this period carried ancestry from Central Europe. This influx likely reflects sustained population movements rather than isolated events.

On the Swedish island of Öland, individuals with Central European ancestry were found to have grown up locally, based on biomolecular analysis of their teeth. This suggests a lasting integration of migrants into Scandinavian communities. 

Archaeological evidence points to periods of conflict in Scandinavia during this time, which may have influenced these movements, though more research is needed to understand the underlying causes.

The Viking Age and genetic mixing

The Viking Age, known for its raiding and settlement activities, left a significant genetic footprint across Europe. The research confirmed that many individuals in Viking-controlled territories carried mixed local and Scandinavian ancestries. 

For example, Viking remains in present-day Ukraine and Russia were linked to Sweden, while those in Britain traced ancestry to Denmark.

Mass graves in Britain containing Viking warriors who died violently further support historical accounts of raiding parties and battles. These findings illustrate the profound impact of Viking expansion on the genetic and cultural landscape of Europe.

A richer understanding of human migrations

These discoveries add depth to historical narratives of human migration patterns during the first millennium AD. 

Peter Heather, co-author and professor of Medieval History at King’s College London, emphasized the significance of Twigstats. 

“Historical sources indicate that migration played some role in the massive restructuring of the human landscape of western Eurasia. Twigstats opens up the exciting possibility of finally resolving these crucial questions,” said Professor Heather.

The study not only validates historical accounts but also offers new perspectives on the scale and trajectories of these migrations. 

By integrating genetic data with archaeological and historical records, researchers can build a more comprehensive understanding of how human populations evolved during this transformative period.

Implications for future research

The success of Twigstats marks a turning point in the study of ancient migrations. 

“The goal was a data analysis method that would provide a sharper lens for fine-scale genetic history,” said senior author Pontus Skoglund, group leader of the Ancient Genomics Laboratory at the Francis Crick Institute.

The team plans to expand the record of ancient genomes to apply Twigstats to other regions and populations worldwide. This could reveal previously unknown migration patterns and deepen our understanding of how human societies have interacted and adapted over millennia.

The intersection of genetics and history

As researchers continue to refine genetic analysis techniques, studies like this offer valuable insights into the complex interplay of migration, culture, and genetics. 

By tracing the movements of ancient populations, scientists not only uncover the roots of modern societies but also provide a framework for understanding the enduring impact of human mobility on the world today. 

The discoveries made possible by Twigstats represent a significant step forward in unraveling the mysteries of human history.

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