Subscribe now for full access and no adverts
Thanks to advances in archaeological science, such as ancient genome sequencing, it is possible to trace how groups of people moved from place to place by tracking changes in their DNA and when/where these mutations were passed down. For groups with very different ancestry – like the hunter-gatherers, early farmers, and steppe pastoralists who shaped the genetic landscape of Mesolithic, Neolithic, and Bronze Age Europe – this is a fairly straightforward task. Until recently, however, there was no reliable way to carry out similar analysis on groups who are genetically very similar, rendering them statistically indistinguishable in such studies.
For example, Roman historians like Tacitus and Ammianus Marcellinus describe the mass movement of Germanic-speaking groups from outside the empire’s borders. Attacks by these peoples are traditionally cited as one of the causes of the fall of the Western Roman Empire – but the exact nature, scale, and genetic impact of these migrations was hard to quantify using previous methods, due to the close ancestral relationships between groups thought to have been involved.
Now a new, more precise way of unpicking ancestry using statistical analysis of ancient DNA has been announced in Nature (see ‘Further reading’ below), describing how it can add flesh to historical bones, complementing surviving written accounts with compelling genetic data. The research, which was led by the Francis Crick Institute, uses a new data analysis method called ‘Twigstats’ to examine the more-recent ‘twigs’ of genetic family trees, measuring differences between even genetically similar groups.
This technique was applied to more than 1,500 genomes from individuals across Europe who lived during the 1st millennium AD. Examples ranged in date from the Iron Age to the Viking Age: a timespan that contains multiple episodes of known large-scale mobility, such as under the Roman Empire and during the early medieval Migration Period (see CA 392). However, the research also revealed evidence of previously undetected waves of human movement across Europe.
From the analysis, we can see at least two different streams of Scandinavian-related ancestry expanding across western, central, and eastern Europe during the early Iron Age. Then, just before the onset of the Viking Age (c.AD 800), another migration of Germanic-speaking people can be seen moving back into Scandinavia, carrying ancestry from Central Europe that is not known from early Iron Age Scandinavia. This was not a one-off movement, but had a lasting genetic impact: isotope analysis of a number of people buried on Öland in Sweden during the Viking Age were found to have this Central European ancestry, but had grown up locally.
Illuminating insights
The Viking Age (c.AD 800-1050) is particularly associated with the movement of Scandinavian people, who embarked on expeditions to raid, trade, and settle, ultimately creating a wide-ranging ‘Viking diaspora’. The Twigstats team’s findings correspond with historical accounts, revealing that many European people who lived outside Scandinavia during this period had a mix of local and Scandinavian ancestry. For example, some individuals in what today is Ukraine and Russia were found to have ancestry from modern Sweden, which tallies with accounts of Scandinavian expeditions into this region; while some individuals in Britain showed evidence of ancestry from modern Denmark.
Further insights specifically into British archaeological sites come from the team’s analysis of individuals from two Viking Age mass graves. One of these, at Ridgeway Hill in Dorset, was excavated by Oxford Archaeology in 2009 (CA 299). There they found the jumbled remains of around 50 individuals, mainly young men, who had died c.AD 970-1020. Every one had been decapitated before being thrown into a quarry pit. The other group was found beneath a quadrangle at St John’s College, Oxford, in 2008 (CA 378); there, Thames Valley Archaeological Services found the remains of 38 individuals, again almost exclusively male, and who also showed signs of suffering a violent death, including fractured skulls and stab wounds. Radiocarbon dating indicates that they were contemporary with the Dorset burial, having died c.AD 960-1020.
The Oxford individuals have previously been interpreted as possible victims of the St Brice’s Day Massacre in 1002, which saw the slaughter of many long-settled Scandinavians on the orders of Æthelred II (Æthelred ‘the Unready’) in retaliation for Viking raids on England. Meanwhile, it has been suggested that the Ridgeway Hill dead might represent a raiding party that was captured and executed by the local population. Twigstats analysis indicates that both groups have genetic ancestry typical of southern Scandinavia.
The study has added interesting new information to our understanding of the Driffield Terrace ‘gladiator’ burials, too, which were excavated by York Archaeological Trust in 2004-2005. Over 80 graves – just part of a much larger cemetery – were uncovered outside the walls of Roman York, and their occupants were intriguing. The vast majority were adult males, and over half had been decapitated. Many also showed extensive signs of healed injuries from earlier in their lives, leading to suggestions that they might represent the remains of soldiers or even gladiators. (See CA 397 for a more detailed account of the cemetery and the individuals buried there.)
Isotope analysis and genome sequencing of seven individuals had already shed light on some of the men’s origins (CA 312), indicating that six were from Britain, while a seventh had Middle Eastern ancestry, with closest parallels to populations in modern Palestine, Jordan, and Syria. Now Twigstats has illuminated the ancestry of one more man from the cemetery. Buried in the 2nd to 4th century, he had already been identified as a genetic outlier – and we now know that he drew 25% of his ancestry from early Iron Age Scandinavia. Not only does this add further detail to our knowledge of the cemetery group but, taking a wider view, it also attests that there were people with Scandinavian ancestry in Britain before the known influx that began in the 5th century with the Anglo-Saxon migrations.
Further reading:
L Speidel, M Silva, T Booth et al. (2025) ‘High-resolution genomic history of early medieval Europe’, Nature 637: 118-126; https://doi.org/10.1038/s41586-024-08275-2 (open access).
