Mice living with humans the longest found to be the best at problem-solving

A team of researchers at the Max Planck Institute for Evolutionary Biology, has found that mice that have been living a commensal life with humans for the longest amount of time are the best at problem-solving. In their paper published in Proceedings of the Royal Society B, the group describes experiments they conducted with mice from different regions.

House mice, as their name suggests, are mice that live in people's homes. The researchers noted that different species of house mice have been living with people for different amounts of time. Mice living in houses in India, for example, have been doing so for much longer than mice living in houses in the U.S. In this new effort, the researchers wondered if mice that have a longer history of sharing their lives with humans in such close proximity are more successful at it.

Mice that live in human houses must have several characteristics to survive—they must be quick (and quiet) so as not to be seen or caught. They must learn how to adapt quickly to changing situations—people are noisy, dart into rooms and turn on lights and behave erratically at times. And they must have some degree of ingenuity—to figure out how to open human-made food packages, for example. In short, they need to be good problem solvers. It was this last characteristic that the researchers chose to study. Have mice that have been living longer with people become better problem solvers than mice who are still relatively new to the game?

To find out, the researchers obtained species of mice from three locales around the world—the mice from each location represented their historical legacy, going back 3,000 to 11,000 years. The researchers tested each of them using a variety of contraptions with the goal of measuring general problem-solving, novelty seeking (behaviors in response to unique conditions) and control of unsuccessful motoric actions (the ability to refrain from engaging in activities that would alert humans to their presence—such as not gnawing on noisy cereal).

The researchers found that the mice that have been living with humans the longest were the best at problem-solving. Further testing showed that the differences were not due to environment but to evolutionary cognitive changes.