Where did the mice come from? - briefly
Mice usually come from adjacent nesting locations such as fields, barns, or storage areas and enter buildings in search of food and shelter. Their intrusion often exploits structural gaps that provide easy access.
Where did the mice come from? - in detail
The inquiry concerns the provenance of the common house mouse and its wild relatives. Scientific investigation identifies three principal sources: indigenous populations, accidental transport, and deliberate introduction.
• Indigenous populations – several species originated in distinct biogeographic zones. Mus musculus domesticus evolved in the Near East, M. m. musculus in Central Asia, and M. m. castaneus in Southeast Asia. Fossil records and radiocarbon dating place their emergence between 10 000 and 5 000 years ago, coinciding with early agricultural settlements.
• Accidental transport – grain shipments, timber, and other commodities provided vectors for passive dispersal. Archaeological layers at medieval ports reveal mouse remains shortly after the introduction of bulk trade, indicating rapid colonisation of new regions without direct human intention.
• Deliberate introduction – historical documents describe intentional placement of rodents for laboratory research, pest control experiments, and as food sources. These actions accelerated spread into isolated islands and remote colonies, as confirmed by genetic bottleneck signatures in contemporary populations.
Genetic analyses support this framework. Mitochondrial DNA haplotypes cluster according to the three lineages, with admixture zones corresponding to trade routes such as the Silk Road and Atlantic shipping lanes. Population‑genetic models estimate a median dispersal distance of 30 km per generation in natural habitats, contrasted with jumps of several thousand kilometres via maritime cargo.
The synthesis of paleontological evidence, historical records, and molecular data provides a comprehensive explanation of how the mouse attained its present global distribution.