House Mice Traveled With Vikings in Their Longships

Posted on March 19, 2012

Norwegian house mice traveled with the Vikings in their longships during the late 8th to mid 10th century. New research, published here in BMC Evolutionary Biology, has used evolutionary techniques on modern day and ancestral mouse mitochondrial DNA to show that the timeline of mouse colonization matches that of Viking invasion.

The house mice traveled with the Vikings as they established colonies across Scotland, the Scottish islands, Ireland, and Isle of Man. The Vikings also explored the north Atlantic, settling in the Faroe Islands, Iceland, Newfoundland and Greenland. The Vikings intentionally took domestic animals with, such as horses, sheep, goats and chickens. Unfortunately, they also inadvertently carried pest species, including mice.

Researchers from the UK, USA, Iceland, Denmark and Sweden used techniques designed to characterize genetic similarity to determine a mouse colonization timeline. Modern samples of mouse DNA were collected and compared to ancient samples dating mostly from the 10th to the 12th century. Samples of house mouse DNA were collected from nine sites in Iceland, Narsaq in Greenland, and four sites near the Viking archaeological site, L'Anse aux Meadows, in Newfoundland. The ancient samples came from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland.

Analysis of mouse mitochondrial DNA showed that house mice (M. m. domesticus) hitched a lift with the Vikings, in the early 10th century, into Iceland, either from Norway or the northern part of the British Isles. From Iceland the mice continued their journey on Viking ships to settlements in Greenland. However, while descendants of these stowaways can still be found in Iceland, the early colonizers in Greenland have become extinct and their role has been filled by interloping Danish mice (M. m. musculus) brought by a second wave of European human immigrants.

Dr. Eleanor Jones, from the University of York and lead study author, says, "Human settlement history over the last 1000 years is reflected in the genetic sequence of mouse mitochondrial DNA. We can match the pattern of human populations to that of the house mice."