Sequenced DNA Sheds Light on Origins of First Scandinavians

Scandinavia was one of the last areas of Europe to be inhabited, due to a combination of a harsh climate and an ice sheet preventing colonisation by early humans. Two distinct genetic variations bear witness to two main immigration waves, one from the south (present-day Germany) and the other one from the northeast (present-day Russia).

An interdisciplinary research team at Lund University, Sweden, has sequenced the genomes of several hunter-gatherers, dated to be 9,500-6,000 years old to dispel the shroud of mystery surrounding the earliest people on the Scandinavian peninsula.

In an effort combining genetic and archaeological data with reconstructions of the ice sheets that during the Ice Age prevented early human populations from contact and migration, DNA data has been extracted from the bones and teeth of seven humans from the Norwegian Atlantic coast and Sweden's Baltic islands of Gotland and Stora Karlsö.

The genomic data was subsequently compared with the genetic variation of contemporary hunter-gatherers from other parts of Europe. It turned out that hunter-gatherers from the Norwegian Atlantic coast were genetically more similar to contemporaneous populations from east of the Baltic Sea, while hunter-gatherers from what is Sweden today were genetically more similar to those from central and western Europe.

According to the researchers, this means that there were two main migrations into Scandinavia: an initial one from the south (modern-day Denmark and Germany) that took place just around 11,700 years ago, followed by an additional migration from the northeast, following the Atlantic coast in northern Finland and Norway becoming free of ice.

The two groups that came to Scandinavia were originally genetically quite different, having quite distinct physical appearances. The people from the south had blue eyes and relatively dark skin. The people from the northeast, by contrast, had a variation of eye colours and pale skin.

These findings agree with archaeological observations that the earliest occurrences of stone tool technology in Scandinavia were recorded in present-day Finland, northwest Russia, and Norway – dating to about 10,300 years ago. By contrast, the same technology only appeared in what is now southern Sweden and Denmark later on.

The knowledge about the genomes of the early hunter-gatherer groups allowed for a deeper look into the population dynamics in Stone Age Scandinavia. These groups met and mixed in Scandinavia, creating a population more diverse than contemporaneous central and western European hunter-gatherers. This, according to the researchers, is in stark contrast to the pattern we see today where genetic variation is stronger in southern Europe compared with the north.

However, modern people of northern Europe trace relatively little genetic ancestry back to the early Scandinavians, the researchers concluded. This is due to several later waves of migrations that changed the Scandinavian gene pool over time, including later in the Stone Age and the Bronze Age.

Scandinavia was one of the last areas of Europe to be inhabited, due to a combination of a harsh climate and an ice sheet that long put a damper on early colonisation. While early humans likely reached Europe from the southeast no later than 42,000 years ago, Scandinavia wasn't colonised until some 11,700 years ago.