New Genetic Insights into the Anglo-Saxon Transition in Britain

In the largest early-medieval ancient DNA study to date, an interdisciplinary team consisting of geneticists and archaeologists - led by the Max Planck Institute for Evolutionary Anthropology in Germany - analysed over 400 individuals from ancient Britain, Ireland, Germany, Denmark and the Netherlands. The results show in detail one of the largest population transformations in the post-Roman world.

Around 300 years after the Romans left, the Venerable Bede wrote about the Angles and the Saxons and their migrations to the British Isles. Scholars of many disciplines, including archaeology, history, linguistics and genetics, have debated what his words might have described, and what the scale, the nature and the impact of human migration was at that time.

For the last 30 years many archaeologists have favoured a view that whilst the cultural impacts of this migration was huge – profoundly changing the language and forms of objects used – the genetic impact would have been minor.

However, new ancient DNA results show that around 75 percent of the ancestry of individuals in Eastern and Southern England was from continental regions bordering the North Sea, - including the Netherlands, Germany and Denmark.

What is more, these incomers interbred with the existing population of Britain, but importantly this integration seems to have varied from region to region and community to community.

“With 278 ancient genomes from England and hundreds more from Europe, we now gained really fascinating insights into population-scale and individual histories during post-Roman times”, says Joscha Gretzinger, a geneticist and archaeologist from the Max Planck Institute for Geoanthropology in Jena, and a lead author of the study. “Not only do we now have an idea of the scale of migration, but also how it played out in communities and families.”

Using published genetic data from more than 4,000 ancient and 10,000 present-day Europeans, Gretzinger and colleagues identified subtle genetic differences between the closely related groups inhabiting the ancient North Sea region.

Migrants intermixed with the local population

Upon arrival, the migrants intermixed with the local population to some extent. In one case, in an Anglo-Saxon cemetery from Buckland near Dover, researchers were able to reconstruct a family tree across at least four generations and identify the point in time when migrants and locals intermarried. This family showed a large degree of interaction between the two gene pools. Overall, the researchers witnessed prominent status burials across the studied cemeteries that comprised individuals of both local and migrant origin.

The interdisciplinary team consisting of over 70 authors, including Prof Mark Thomas from UCL, was able to integrate archaeological data with these new genetic results, which revealed that women of immigrant origin were buried with artifacts more often than women of local origin, especially when considering items such as brooches and beads.

“There have been a number of previous genetics studies trying to establish the scale of migration” said Prof Thomas. “Studies based on DNA from people alive today have indicated a substantial migration, but there is no substitute for analysing DNA from people who lived around the time of this formative transition in British history. Earlier ancient DNA studies also indicated substantial migration, but this latest study has so much more power.

Questions remain about how the migrants mixed with indigenous Romano-British people in the generations following the initial migrations.

Duncan Sayer, archaeologist from the University of Central Lancashire and a lead author of the study says “We see considerable variation in how this migration affected communities. In some places, we see clear signs of active integration between locals and immigrants, as in the case of Buckland near Dover, or Oakington in Cambridgeshire. Yet in other cases, like Apple Down in West Sussex, we see that people with immigrant and local ancestry were buried separately in the cemetery. Perhaps this is evidence of some degree of social separation at this site.”

“Understanding how the continental migrants mixed is important” added Prof Thomas, “because the way they intermarried influenced genetic and cultural patterns in the coming generations. This study is a key step in building a more nuanced understanding of the transition that fundamentally shaped England genetically and culturally today”.

Impact of this historic migration on present-day English people

With the new data, the team could also consider the impact of this historic migration today. Notably the present-day English derive only 40 percent of their DNA from these historic continental ancestors, whereas 20 to 40 percent of their genetic profile likely came from France or Belgium. This genetic component can be seen in the archaeological individuals and in the graves with Frankish objects found in early Medieval graves, particularly in Kent.

“It remains unclear whether this additional ancestry related to Iron Age France is connected to a few punctuated migration events, such as the Norman conquest, or whether it was the result of centuries-long mobility across the English Channel”, says Stephan Schiffels, a population geneticist at the Max Planck Institute for evolutionary Anthropology, Leipzig, Germany, and senior author of the study. “Future work, specifically targeting the medieval period and later will reveal the nature of this additional genetic signal.”

Further discussion of this work will be available in a special issue of Current Archaeology Magazine in print on the 6th of October.

https://doi.org/10.1038/s41586-022-05247-2