Monday, January 30, 2023

Anglo-Saxons and Irish left lasting legacy in Vikings’ DNA

In TV’s Vikings, the Northumbrian monk Athelstan, shipped back to Norway by Norse raiders, is propositioned by the shield maiden Lagertha and her warrior husband Ragnar Lothbrok. He resists temptation and Lagertha later falls for another Anglo-Saxon cleric, Bishop Heahmund.

The enslaved monk’s ordeal may be fictional, but a new study suggests that Viking Age slaves — and possibly missionaries — contributed to a lasting British and Irish legacy in the Scandinavian gene pool.

A multinational team studied the genetic history of Scandinavia over 2,000 years, from the Iron Age to the present. Their analysis is based on 48 new and 249 previously published human genomes from archaeological sites, together with DNA from over 16,500 living people. Besides Viking burials, the remains included those of people massacred at the Sandby borg ring fort around 500AD and sailors who died in the sinking of the Swedish warship Kronan in 1676.

The scientists’ findings point to a surge of gene flow from the British Isles right across Scandinavia during the Viking Age, from around 750-1050AD. This had a “small” but enduring impact on the DNA of modern Scandinavians. The study also identifies gene flow from the eastern Baltic in the later Viking period, although this was localised to Gotland and central Sweden. In addition, the team found evidence of Southern European ancestry in some Viking Age remains. There was little evidence of gene flow from these regions in pre-Viking times.

Intriguingly, levels of DNA from other regions were higher across the sample of Viking Age remains than in modern Scandinavians not of recent migrant descent. Geneticist Ricardo Rodríguez-Varela, of Stockholm University, the lead author, said: “This suggests that ancient individuals with non-Scandinavian ancestry contributed proportionately less to the current gene pool in Scandinavia than expected based on the patterns observed in the archaeological record.”

Remains excavated at the 5th century ringfort of Sandby borg in Sweden were among those analysed in the study. Photo: Daniel Lindskog

The Vikings’ long-distance trading and raiding networks and military conquests could all help to account for the influx of non-Scandinavian genes into the region, according to the researchers. People from the British Isles, eastern Baltic and elsewhere may have arrived as slaves, traders or Christian missionaries, or through marriages. By the 10th century, the Vikings’ trading networks extended from Iceland in the west to Baghdad in the east and they had raided as far south as Muslim Spain and North Africa.

Scandinavians had a strong presence in the British Isles from the early Viking raids of the 8th century to the settlement of the Danelaw and incorporation of England into the 11th-century North Sea Empire of the Danish kings Sweyn Forkbeard and Cnut. In Ireland they founded the kingdom of Dublin and ports including Cork and Limerick.

In their paper, in the journal Cell, the researchers write: “Gene flow from the British-Irish Isles during this period seems to have had a lasting impact on the gene pool in most parts of Scandinavia. This is perhaps not surprising, given the extent of Norse activities in the British-Irish Isles . . . The circumstances and fate of people of British-Irish ancestry who arrived in Scandinavia at this time are likely to have been variable, ranging from the forced migration of slaves to the voluntary immigration of more high-ranking individuals such as Christian missionaries and monks.”

A woman discovered in a boat burial at Sana in central Sweden is an interesting case. She was buried around 950-1000, with three brooches and a wooden box. Her DNA indicates that her ancestry was from the British Isles. However, strontium isotopes in her teeth suggest that she was born and raised locally, in Sweden. The researchers speculate that she was a second-generation immigrant with a high social status in the community.

The scientists said the situation was very different for a woman of British or Irish ancestry buried at Gerdrup in Denmark during the 5th century without grave goods. This was before the Viking Age and they suggest that she may have ended up there as a result of the Anglo-Saxon migrations to Britain from today’s Northern Germany and Denmark. In other words, she travelled to Scandinavia as part of the movements back and forth between the continent and new settlements in Britain.

They added: “Although this finding indicates that British-Irish gene flow into Scandinavia began at least as early as the 5th century . . . our results suggest that most of it likely occurred during the Viking Age.”

As for the Baltic ancestry observed in Swedish Vikings, this would be consistent with their control of trade around the Baltic sea and recorded contacts with Baltic peoples. The results suggest that gene flow from the eastern Baltic to Scandinavia tended to be through women and this was also true, to a lesser extent, for gene flow from the British Isles. Nevertheless they observed direct evidence in the human remains for men from Britain or Ireland arriving in Scandinavia.

The team said there could be several explanations for the higher levels of non-Scandinavian ancestry observed in Viking remains than in modern Scandinavians. For one thing, remains from archaeological sites may not be representative of the Viking Age Scandinavian population as a whole. Several of the samples are from Viking towns with extensive trade networks and these may be overrepresented in the dataset.

The researchers also noted that many incomers from the British Isles and eastern Baltic may have been of low social status and therefore less likely than others to have left descendants. And they said that, until the early Viking Age, cremation was the main funerary tradition in Scandinavia, so that remains that yield DNA may not be representative of the wider population.

Among further findings, the team concluded that a previously observed North-South difference in Scandinavians’ genetics goes back to the Viking Age or earlier. The difference was primarily due to higher levels of Uralic ancestry, similar to that of modern Finns, in northern Scandinavians.

More recent remains studied included those of sailors of the Swedish warship Kronan, which sank during the 17th-century Battle of Öland. Photo: Lars Einarsson

Previous studies have shown that Vikings didn’t only acquire ancestry from other regions but left a Scandinavian genetic footprint across a broad area. A study in 2020 found that, while genes similar to those of today’s Norwegians were widespread in Iceland, Greenland, Ireland and the Isle of Man, “Danish-like” DNA was more common in England. However, the scientists said it was impossible to distinguish the genes of Danish Vikings from those of the Angles and Jutes who migrated to Britain from today’s Denmark and Northern Germany in the 5th and 6th centuries.

The authors of that earlier study also stressed that Viking identity was fluid and that people of entirely non-Scandinavian ancestry were sometimes buried as Vikings and evidently part of the Viking community.

The top image shows Katheryn Winnick and Jonathan Rhys Meyers as Lagertha and Bishop Heahmund in TV’s Vikings © History Channel/Everett Collection, via Alamy.

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