(note - this article comes from ASM's 2010 Public Communications Award winner Debora MacKenzie)
Could playing in the dirt make you smarter? Studies in mice suggest that it could.
Mice given peanut butter laced with a common, harmless soil bacterium ran through mazes twice as fast and enjoyed doing so. So says Dorothy Matthews of the Sage Colleges in Troy, New York state, who presented her results at the annual meeting of the American Society for Microbiology in San Diego, California, this week.
In a classic test of learning ability, Matthews gave mice a treat – white bread with peanut butter – as a reward to encourage them to learn to run through a maze. When she laced the treat with a tiny bit of Mycobacterium vaccae, she found that the mice ran through the maze twice as fast as mice that were given plain peanut butter. This suggests that they had learned to navigate the maze faster, Matthews says.
Moreover, the mice given the bacteria continued to run the maze faster than those without it for 18 more trials over the next six weeks, showing they weren't just made more alert by a surprise change to their treat. This effect lasted for four weeks after the last piece of doctored peanut butter was given to the mice.