More than thousand years ago, marauding Vikings terrorized Europe and struck as far west as Newfoundland in their long ships, leaving their mark on the countries they raided and sometimes put down roots.
Now it turns out the axe-wielding, horny-helmeted Norsemen weren't the only adventurers on those vessels.
A new study has found the common house mouse hitched a ride on those ships and conquered their own frontiers in the places the Vikings colonized.
With one exception, according to Postmedia News's Randy Boswell.
Just like the Vikings, the house mouse apparently couldn't handle the harsh climate of northern Newfoundland, where the famed Leif Ericsson established a settlement at L'Anse aux Meadows.
The Vikings abandoned their embryonic colony after clashing with local aboriginal people, leaving few traces of their presence. And no mice.
The study was led by evolutionary biologist Eleanor Jones and published in the journal BMC Evolutionary Biology.
The research team found no genetic connection between modern Newfoundland mice and those found in Iceland and Greenland, which shared DNA markers from mice remains linked with Norwegian Vikings.
According to Postmedia, the scientists found proof that bloodlines from the species Mus musculus domesticus already known to have been carried by Vikings from Norway to medieval Scotland and Ireland also found their way to Iceland and Greenland.
When investigating the defunct Newfoundland colony, researchers found no DNA evidence of Viking-era mice. The Rock's current resident mice are thought to have descended from later English and European ships.
"If mice did arrive in Newfoundland, then like the Vikings, their presence was fleeting and we found no genetic evidence of it," said Cornell University researcher Jeremy Searle, who co-authored the study.
The research article said that while evidence suggests Norwegian house mice present in other locations, scientists could only speculate whether house mice arrived in the Viking period at all, since they had no remains to work with.
"Had the mice been introduced onto Newfoundland, it is uncertain whether they would have been able to survive in a free-living state on the island when the Viking people left," the study said. "In some situations house mice are able to form long-term outdoor populations and in others they are not.''
The Viking mice's adventures tickled The Register, which reported the study this way: "Virile Norse mice rampaged through Scotland, Ireland and Iceland impregnating locals and mixing their Viking mouse genes in the native rodent populations ..."