DNA reveals large migration to Scandinavia during the Viking Age

We often think of the Vikings as the ultimate explorers, bringing their culture to distant lands. But we may not usually think of Viking Age Scandinavia as a hub for migration from all over Europe.

In a study published in Cell, we show that this is exactly what happened. The Viking Age (late 8th century to mid 11th century) was the catalyst for an exceptional influx of people into Scandinavia. These movements were greater than for any other period we analyzed.

What is also striking is that later Scandinavians do not show the same high levels of non-local ancestry found in their Viking Age counterparts. We do not fully understand why the genetic influence of migrants decreased in later Scandinavians, but there are some possibilities.

We analyzed genomes (the full complement of DNA found in human cells) from around 17,000 Scandinavian individuals, including nearly 300 from ancient burials. We combined existing data sets with new samples. These were analyzed together in a dataset spanning 2,000 years.

We used these genomes to explore when people arrived in the region from outside and where they came from. New DNA samples were collected from several iconic Swedish archaeological sites.

These included Sandby Castle, which is a “ring fortress” where a massacre occurred shortly before 500 AD, and Vendelkyrkogården, which has several burials found in large boats and dated to between the 6th and 8th centuries AD. We also used samples from Viking chamber burials and remains from Kronan, a warship that capsized with more than 800 men year 1676.

Two previous studies noted extensive migration into Scandinavia during the Viking Age. However, in our latest study, we have clarified some of the details of this gene flow into the region.

We found that movements of people from Western Europe affected the whole of Scandinavia, while migration from the East was more localized, with peaks in Mälardalen and . Finally, gene flow from southern Europe largely affected southern Scandinavia.

Because the study was based on a 2,000-year chronology, it was not only possible to see an increase in migration during the Viking Age, but also that it begins to decline with the beginning of the .

The non-local ancestors arriving in the region at this time disappear in later periods. Much of the genetic influence from Eastern Europe disappears and the Western and Southern influence becomes significantly diluted. The best way to explain this is that people who arrived in Scandinavia during the Viking Age did not have as many children as those who already lived there.

There are various possible reasons for this. The migrants could have belonged to groups that had no intention of settling in Scandinavia, instead aiming to return to where they came from. Merchants and diplomats are examples in this category. In addition, the migrants could also have belonged to groups that were not allowed to have families or children, such as slaves and priests.

We also looked at influences that started in earlier periods. For example, the DNA of modern Scandinavians gradually changes as you travel from north to south. This genetic “cline,” or gradient, is due to migrations into the region of people who carry shared genetic similarities known as the Uralic component.

Modern examples of where the Uralic genetic component can be found are among the Sami people, people in modern , some Native Americans, and some Central Asian groups.

In our data set, we found single instances of people with Uralic ancestry – mainly in northern Scandinavia – during the Viking Age and the Middle Ages. However, Uralic influence appears to increase after this time, as individuals from our 17th century sample have similar levels of this ancestry to people living today.

There were many other fascinating stories from our study. For example, at the Viking burial site of Sala, on the river Sagån, we find a woman who appears to be entirely British or Irish in her genomic makeup. This woman was buried in a prestigious boat burial from the Viking Age. We do not know exactly what position she held in society, but she would not have been a slave or a priest.

Among the individuals found on the wreck of the Kronan were two people who came from what is now Finland and another who has a genetic affinity with people from the Baltic states, such as and (although this identification is not conclusive). At the time of the Kronan Incident in 1676, these areas were part of the Swedish Empire, although today they are independent.

The work sheds more light on the historical events that shaped the population of Scandinavia over time. The Viking Age was characterized by Scandinavians’ curiosity about the world outside their home territory. But our results also show that the world outside this region was curious enough about the Vikings to travel to Scandinavia.

Author: Anders Gtherström – Professor of Molecular Archaeology, Department of Archeology and Classical Studies, University | Ricardo Rodriguez Varela – Research in Molecular Archaeology, Department of Archeology and Classical Studies, Stockholm University, Stockholm University The conversation

Source: sn.dk


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