A recent study of ancient DNA sheds light on who the Viking groups were and how they interacted with the people they met. The Viking Age, from around 750 to 1100 CE, left a cultural and economic impact that stretched from the coast of North America to the Central Asian steppe, and archaeology shows several examples of cultural exchange spanning continents. But to see patterns in how people swapped not only ideas, but genes, we need to look at the DNA of ancient people.
“We know very well that the Viking Age changed the cultural and political map of Europe a thousand years ago, but we don't really know much about the demographic changes that accompanied these changes,” University of Copenhagen genomicist Ashot Margaryan told Ars. “This can be addressed based on population genetics methods.”
Who were the Vikings?
Today, we tend to think of the Vikings as one big mass of bearded raiders, swooping down European coasts, up rivers, and across the North Atlantic. But the Vikings didn’t see themselves that way at all. The people who set sail to raid, trade, fish, and settle during the Viking Age saw themselves as members of distinct groups, with a shared culture but not a shared identity. The genetic evidence, it turns out, is on the Vikings’ side.
Margaryan and his colleagues recently sequenced genomes from 442 people who lived between 2400 BCE and 1600 CE. The remains of these people were unearthed at archaeological sites across Europe and Greenland, including Scandinavia itself. When authors compared those genomes to each other and to hundreds of published genomes from modern people, they found subtle differences that sorted Scandinavian people into four groups, which closely resembled people now living in Sweden, Norway, Denmark, and the British Isles.
A closer look at some of those differences offers some hints about how people in northern Europe may have moved around and interacted just before the start of the Viking Age. Archeologists and historians are still debating what caused seafarers in several places at once to take up raiding. It could be the result of new people and ideas moving into Scandinavia or due to turmoil and migrations within the region. Without a clear picture of the population from this time, it's difficult to know whether population movements might have contributed.
We do know that all of the groups of people who sailed from Scandinavia during the Viking Age descended from the people who lived there during the Iron Age (500 BCE to 800 CE—not to be confused with the Swedish Death Metal Age, which started in the early 1990s CE). But the genetic data does suggest a few differences. For instance, Viking Age people from Sweden and Denmark have more ancestry in common with Neolithic farmers from Anatolia, who spread west across Europe around 6,000 years ago, than their predecessors did. That suggests the flow of people and their genes from the south and east, moving across the Baltic Sea and into Sweden and Denmark just before the Viking Age.
That doesn’t tell us a tremendous amount on its own, but enough tiny puzzle pieces like this one will eventually be enough to at least suggest what the complete picture might look like.
Close encounters of the medieval kind
Because Margaryan and his colleagues included genomes from people who lived and died centuries before the Viking Age, it’s possible to track how genetic diversity changes over time in certain places. Some, like the Swedish islands of Gotland and Ӧland, had been diverse communities since the first century CE. But others, like the central Danish islands, experienced a sudden flourishing of genetic diversity around the time the Viking Age started, pulling places like Langeland into much closer and more frequent contact (ahem) with distant places.
The genetic evidence tells the same story as history and archaeology: once the Viking Age began, each of the Scandinavian groups had its own trade routes, contacts, settlements, and raiding areas. People sailing from Sweden mostly went east; people from Norway mostly went to western Europe and across the Atlantic to Ireland, the Isle of Man, and eventually to Iceland and Greenland; people from Denmark mostly went to England.
Of course, the story is always a little more complex than it seems; Margaryan and his colleagues found a person with Danish ancestry in what’s now Russia, and Norwegians were among people executed (possibly for raiding) in early medieval England.
“It is likely that many such individuals were from communities with mixed ancestries, thrown together by complex trading, raiding, and settlement networks that crossed cultures and the continent,” wrote Margaryan and his colleagues. And the people of all of those far-flung places left a lasting genetic legacy in the Vikings and their home ports.
The genomes suggest that new genetic material flowed to and from Scandinavia along those established trade and raiding routes. Historical and archaeological evidence tells us that people from Norway sailed to parts of the British Isles, for example, and today the average Norwegian gets between 12 to 25 percent of their ancestry from those places. The genomes of people from archaeological sites in Sweden, on the other hand, get more of their ancestry from people in eastern and central Europe.
Welcome to the raiding party
That mixing happened more often—and sooner—in coastal areas, in southern Scandinavia, and in large cities. Margaryan and his colleagues found less genetic diversity in people from inland, northern, and rural regions than in people from more cosmopolitan places. That’s not surprising, but it indicates that Vikings mingled pretty freely, and on a large scale, with the people they encountered on their travels. They were also willing to welcome outsiders into their own culture.
“Our results show that ‘Viking’ identity was not limited to individuals of Scandinavian descent,” wrote Margaryan and his colleagues. Two of the first Pictish genomes ever sequenced came from people buried in Scandinavian-style graves in Orkney, after all, and archaeologists have found a number of other non-Scandinavians buried in similar graves, including some who apparently originally came from Muslim countries.
Nature, 2020 DOI: 10.1038/s41586-020-2688-8 (About DOIs).
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