Where Vikings went, mice followed

YORK, England, March 19 (UPI) -- When Vikings spread across Europe and into the New World, researchers say, they took one unintended "guest" along on their journeys -- the humble house mouse.

In addition to the domestic livestock such as horses, sheep, goats and chickens they took to colonies in Scotland, Ireland, Iceland, Greenland and possibly Newfoundland, they inadvertently took pest species such as mice with them, a study in the journal BMC Evolutionary Biology reported.

Analysis of ancient mouse DNA in modern rodent populations showed the house mice hitched a ride with the Vikings in the early 10th century into Iceland from either Norway or the northern part of the British Isles, and from Iceland continued their journey on Viking ships to settlements in Greenland.

"Human settlement history over the last 1,000 years is reflected in the genetic sequence of mouse mitochondrial DNA," Eleanor Jones from the University of York in Britain said. "We can match the pattern of human populations to that of the house mice."

The researchers said lessons could be gained from both where ancient mouse DNA is found today and where it is not.

"Absence of traces of ancestral DNA in modern mice can be just as important," Jeremy Searle from Cornell University said. "We found no evidence of house mice from the Viking period in Newfoundland.

"If mice did arrive in Newfoundland, then like the Vikings, their presence was fleeting and we found no genetic evidence of it."