The genetic history of Scandinavia from the Roman Iron Age to the present

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A 2,000-year genetic transect reveals how migration shaped Scandinavia from the Iron Age to today.

This study traces Scandinavian genetic history over 2,000 years using 48 new and 249 published ancient genomes, plus genotypes from 16,638 modern people. It finds that gene flow from the eastern Baltic, the British-Irish Isles, and southern Europe varied by region and time. British-Irish ancestry spread widely during the Viking period, while eastern Baltic ancestry stayed more local. In some areas, modern people have less external ancestry than Viking or Medieval genomes would suggest, meaning ancient immigrants contributed proportionally less to today's gene pool.

• British-Irish ancestry was widespread in Scandinavia from the Viking period, while eastern Baltic ancestry was more localized to Gotland and central Sweden.
• In some regions, modern external ancestry levels are lower than those in Viking and Medieval genomes, suggesting ancient immigrants contributed proportionally less to the modern gene pool.
• A north-south genetic cline in modern Scandinavians mainly reflects different levels of Uralic ancestry, and this cline already existed in the Viking Age and possibly earlier.

Sample interpretation

The 52 site samples include 36 with resolved Y-haplogroups. Cultures range from Pre-Viking to Late Viking and Post-Medieval, mostly from central and south Sweden, with a few from Gotland and north Sweden. Top Y-haplogroups include N-L550, I-L813, and I-DF29, each with two samples. Top mtDNA lineages include H1b1-T16362C, V, I1a1, J1c4, and U4a2b, each with two samples. The largest site samples are kro015 (12), urm035 (9), and snb019 (7).

For genealogy enthusiasts

For ancestry enthusiasts, this shows Scandinavia's genetic history is not a single story: Viking-era migration left different marks in different regions, and modern Scandinavians carry less external ancestry than some ancient genomes suggest. The north-south Uralic cline is a deep, long-standing feature.