They may not have raped and pillaged, but 鈥淰iking鈥� mice conquered the outer reaches of the British Isles all the same.
Rodents living in Wales, Scotland and Ireland can trace their ancestry to Norwegian house mice, presumably stowaways on Viking ships.
Because grain-eating house mice 鈥� Mus musculus domesticus 鈥� depend on dense human populations, they serve as a reliable proxy for human settlement and migration, says , an evolutionary biologist at the University of York, UK, who led the new study.
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鈥淚t鈥檚 just a completely different angle to look at and potentially add new pieces of evidence that historians and archaeologists can use,鈥� he says.
The discovery that mice made the journey to the northern and western British Isles at the time of the Vikings isn鈥檛 much of a surprise in itself. The Orkney Islands served as a major Norwegian Viking settlement in the 11th and 12th centuries, and rodents probably sailed between Scandinavia and Scotland.
Earlier settlers
What surprised Searle鈥檚 team was the difference in mitochondrial DNA from these 鈥淰iking鈥� mice and those recovered in other parts of Britain. When they examined the ancestry of rodents from elsewhere in the British Isles, they found a link to Bronze Age human migrations, beginning about 2300 BC.
This probably means that the Vikings were the first humans to live densely enough in Scotland and Ireland to support house mice, Searle says.
鈥淚f a place is empty of mice the first that come are the winners,鈥� agrees Fran莽ois Bonhomme, an evolutionary biologist at Montpelier University, France, not involved in the study. 鈥淥ne boat with three mice 鈥� that鈥檚 sufficient to start a population.鈥�
Other such human and house mice populations should prove more interesting and enlightening, Searle says. 鈥淣ow that we鈥檝e got a Viking mouse, if you like, we can actually focus on much more specific aspects of Viking history.鈥�
For instance, mice could solve two puzzles about the settlement of Iceland. Some historians think that Iceland was home to multiple Viking settlements, each with a different home base in the Viking kingdom, a contention that mice could bolster.
Also, the Hebrides may have served as a pit stop from Norway to Iceland, where Viking men picked up women for second leg. This theory might be confirmed if DNA from Icelandic mice most closely matches that of Hebridean mice.
Journal reference:
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