Enhanced problem-solving ability as an adaptation to urban environments in house mice.

Humans have a large impact on the distribution and abundance of animal species worldwide. The ecological effects of human-altered environments are being increasingly recognized and understood, but their effects on evolution are largely unknown. Enhanced cognitive abilities and the ability to innovate have been suggested as crucial traits for thriving in human-altered habitats. We tested if house mice (Mus musculus) subspecies have evolved enhanced innovative problem-solving abilities throughout their commensal lives with humans. The time that subspecies lived commensally with humans ranges between approximately 3000 years to more than 11 000 years, thus providing an excellent example of human-animal coexistence. In addition, we tested whether differences in problem-solving were mediated by differences in object and place exploration, motivation, persistence or inhibitory control. We found that populations of subspecies living commensally the longest excelled in problem-solving across seven food-extraction tasks over subspecies living commensally short or intermediate times. These differences were not mediated by exploration, motivation, persistence or inhibitory control suggesting that subspecies have evolved better cognitive abilities when living commensally in urban environments. This suggests that the ability to problem-solve may be an important trait promoting prosperity in human-altered environments.