New genetic research shows influx of Baltic women into Viking-era Sweden

An extensive survey recently published in the open-access scientific resource Cell has revealed a number of unexpected findings concerning the movement of people during the Viking Age. 

The study was led by Stockholm University and the pioneering organization deCODE genetics based in Reykjavík.

The combined work of 44 specialists in this field, The genetic history of Scandinavia from the Roman Iron age to the present, investigates this 2,000-year time span by means of 48 new and 249 published ancient genomes and genotypes from 16,638 present-day individuals. The older examples were elicited from major archaeological sites.

Initially, researchers were working from three separate studies based on different sites, most notably the Swedish warship Kronan, one of the largest of its kind when it was transporting a huge amount of coins and weaponry in the 1670s. Some can be seen in the Kalmar County Museum.

Trade and migration

Instead of three different studies, researchers decided to pool their findings, compare them with a large sample group today, and create an overall picture spanning two millennia. It is believed to be the most overarching study of its kind.

From data gleaned in this way, the team has been able to pinpoint regional variations of genes from three main sources: the eastern Baltic, the British-Irish Isles, and southern Europe.

Motivated by international trade in silver, silk, and, crucially for this study, slaves, Vikings interacted with four continents, the first people to do so. 

They reached as far as the western end of the Silk Road, the Caucasus, the Levant, and North Africa. Slave trading was commonplace between Vikings and the Islamic world, in both directions, meaning the first arrival of globally diverse foreign genes into Scandinavia. 

It also led to the probable if modest spread of Scandinavian genes in Morocco, where the Vikings spent a period of time in the mid-800s.

Whereas the expansion of British and Irish genes can be detected right the way across Scandinavia – ties between the two regions were multi-layered for the whole extent of the Viking Age – the presence of southern European genes is mainly perceived in southern Scandinavia.

The survey pays particular attention to a discovery in a gravel pit near Eksta, on the island of Gotland. Photo: Anna Andersson Fotografi / Shutterstock

Baltic roots

And, most intriguingly, there is a strong strain of female genes from the eastern Baltic region in central Sweden and the island of Gotland, which lies halfway between the southeast coast of Sweden and modern-day Latvia. This makes it a natural entry point.

Quoted in a press release related to the publication of the survey, Nils Anders Götherström, a molecular archaeologist attached to Stockholm University, suggests that migration from the west impacted all of Scandinavia, while migration from the east was sex-biased, with movement primarily of females into the region. 

The main reason for this is thought to be the trade in slaves, or thralls – the Norse root of the modern-day English expression, "in thrall to." This was a system that stayed in place across Scandinavia until the mid-1300s, long after the Viking heyday.

The survey refers to a specific discovery in a gravel pit near Eksta, on the south-west coast of the island of Gotland:

"The remains of a female skeleton were accidentally found in 1931 in a gravel pit in Kvie, five kilometers off the coast in Eksta parish in southwestern Gotland. The remains were revealed to be part of an inhumation burial, poorly furnished with only two eyed bone pins, and five beads: two of shell, two natural stones and one amber bead, and a piece of iron thread. Four more graves were later excavated and were typologically dated to the Viking Age. Although belonging to the Viking Age, the inhumation does not resemble a traditionally Gotlandic female burial. This may indicate that the individual could have been of low social standing, possibly a thrall... osteologically, the skeletal parts were determined as belonging to a female 55–60 years of age".

Additional genetic data, particularly from northern Scandinavia, should allow the research team to ascertain when the so-called north-south cline – the delineation of the geographic variation between populations – came into being.

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