NEW YORK – Viking ancestry and interactions appear to have been far more complex than previously appreciated, according to a new ancient DNA analysis.
"Many Vikings have high levels of non-Scandinavian ancestry, both within and outside Scandinavia, which suggest ongoing gene flow across Europe," co-first author Martin Sikora, a researcher at the University of Copenhagen's Centre for GeoGenetics, said in a statement.
For a paper published in in Nature on Wednesday, Sikora and colleagues sequenced DNA from more than 400 individuals buried at ancient Viking cemeteries in Europe and Greenland between the Bronze Age and the Early Modern period, comparing the genomes to sequences from more than 1,100 other ancient individuals, as well as population reference sequence data for almost 3,900 modern-day individuals.
"We found genetic differences between different Viking populations within Scandinavia, which shows Viking groups in the region were far more isolated than previously believed," said co-senior author Eske Willerslev, director of the University of Copenhagen Lundbeck Foundation GeoGenetics Centre, who is also affiliated with the University of Cambridge, the Wellcome Trust Sanger Institute, and the University of Southern Denmark, in a statement.
Willerslev noted that the work "even debunks the modern image of Vikings with blonde hair, as many had brown hair and were influenced by genetic influx from the outside of Scandinavia."
The team saw individuals with Norwegian ancestry moving into places like Ireland, Scotland, Iceland, and Greenland, while Vikings from Denmark typically ventured to England, where the present-day population has roughly 6 percent ancestry from Vikings, and Swedish male marauders moved into Baltic regions. Local raiding parties from each region tended to be made up of mostly brunette locals, many of them related to one another in the early Viking expeditions.
"We discovered that a Viking raiding party expedition included close family members as we discovered four brothers in one boat burial in Estonia who died the same day," co-first author Ashot Margaryan, an evolutionary genomics researcher affiliated with the University of Copenhagen and Armenia's National Academy of Sciences, said in a statement. "The rest of the occupants of the boat were genetically similar, suggesting that they all likely came from a small town or village somewhere in Sweden."
But the available ancestry data indicated that populations moved into Scandinavia from other parts of the world — particularly Southern Europe and Asia — prior to the infamous pirate raids that took place during the Viking Age from 800 to around 1050, the researchers reported, leaving their ancestry mark on Viking expeditions that came later.
"Overall, our analyses suggest that the genetic makeup of Viking Age Scandinavian populations largely derives from ancestry of the preceding Iron Age populations — but these analyses also reveal subtle differences in ancestry and gene flow from both the south and the east," the authors explained.
In addition, ancient DNA from the sites where Vikings ventured hinted that some local individuals may have taken on Viking identities, securing Viking burials despite coming from non-Scandinavian regions. At a notable burial site in Orkney, for example, the researchers identified two individuals with Scottish and Irish origins, in addition to individuals with Scandinavian ancestry, hinting that populations in the region may have adopted Viking-related culture.
Broadly speaking, the results suggested that "Scandinavian diasporas established trade and settlement stretching from the American continent to the Asian steppe," co-author Søren Sindbæk, an archeologist at Denmark's Moesgaard Museum who is also affiliated with Aarhus University, said in a statement. "They exported ideas, technologies, language, beliefs, and practices and developed new socio-political structures."
Beyond these interactions between regions and across the European continent, the team was able to use the ancient genomic data to search for signs of positive selection and other features in the populations in northern Europe — from pigmentation or complex disease risk to immunity or individuals' ability to digest milk sugar with help of the lactase enzyme persistence allele of the lactase gene LCT.