Proc. R. Soc. B doi:10.1098/rspb.2008.0958; 10.1098/rspb.2008.0959; (2008)

Mus musculus, the house mouse, has been colonizing new lands for several thousand years by hitchhiking with the humans whose crumbs it has come to rely on. Jeremy Searle of the University of York, UK, and his colleagues have used mouse mitochondrial DNA to retrace human migration.

They write that mice on the northern and western peripheries of the British Isles, particularly on the Orkney Islands, share a genetic lineage with Norwegian mice. These mice probably arrived with the Vikings — unlike mice from elsewhere in Britain, which are genetically more similar to German mice and probably reflect Iron Age migrations.

House mice on New Zealand, however, come from a mixture of countries, mirroring the complex history of migration to the archipelago from the late eighteenth century onwards. Before that, New Zealand was mouse-free.