May 23, 2014
Mice Run For Fun
Despite their oft-ill regarded reputation, rodents have given us some of the most adorable moments on the Internet, most often derived from their keen fondness for spinning wheels and tendency to overestimate their ability to keep up with said wheel. Almost any pet store that sells mice, rats, or hamsters will likely include one of these wheels with the purchase of such a pet, or at the very least strongly encourage their inclusion. It’s practically a staple of rodent cages, and is often the most common way that the little guys are able to get their exercise despite their domestic environment. However, according to a story appearing in the New York Times, it would appear that small rodents and their love of wheels extend beyond the bars of the household pet cage. Despite initial concern that running on an exercise wheel might actually be a behavioral manifestation of stress (such as an imprisoned bears’ tendency to pace back and forth), two scientists from the Netherlands have observed an interesting phenomenon that would suggest the exact opposite: mice run for fun.
Johanna Meijer, a brain electrophysiologist from Leiden University Medical Center, set up motion-detecting equipment and video cameras around several exercise wheels placed outdoors, curious whether the little creatures would approach and exercise with the same fervor as their caged friends. Twelve thousand video snippets later, they confirmed their suspicions. The video showed wild mice approaching the wheel, hopping on, spinning it, hopping off, and then returning to repeat the process. With no ulterior motivation, the wild mice were tentatively discovering, exploring, and embracing the wheel from between one and 18 minutes. Meijer, who studies the biological rhythms in mice, was delighted by the result: “When I saw the first mice, I was extremely happy … I had to laugh about the results, but at the same time, I take it very seriously. It’s funny, and it’s important at the same time.” Meijer even noted other animals, such as slugs and frogs, using the wheel, though these other animals accounted for less than one percent.
She said that the inspiration for this experiment came from the notes of Konrad Lorenz, one of the most influential progenitors of animal behavior studies, who had once noted that his escaped rats were returning to the gardens to run on the wheels placed there, despite having recently found their freedom. However, Lorenz never went into any more details (at least not in his notes), and the rats that were returning to the wheels had already spent time in captivity. Meijer took the observation a step further, introducing the man-made element into the wild.
Thus far, peer reviews for Meijer’s paper have been largely positive. Dr. Huda Akil of the University of Michigan compared it to children at play on a merry-go round, noting that active “play” stimulates certain reward-centers in the brain. Obviously, the neurological specifics differ greatly between rats and humans, but the basic primal instinct to expend mountains of energy on physical activities for the sake of recreation remains similar … though we humans have certainly gotten better at suppressing it.
Image Credit: Thinkstock