Two researchers in the Netherlands have gone and done the thing that will screw us all in our efforts to remain pleasantly and mildly unhealthy. They've discovered that, when in the wild, mice actually seek out the running wheel as a leisure activity.
Ignoring the sadistic strangeness that is putting a rodent wheel in the beautiful wild for mice to then be drawn to, the researchers found that mice felt rewarded after their wheel-turning, even in the fresh air. As the study was chronicled in the New York Times,
"When I saw the first mice, I was extremely happy," said Johanna H. Meijer at Leiden University Medical Center in the Netherlands. "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."
The premise of the study was simple:
For the experiment, the wheels were enclosed so that small animals could come and go but so that larger animals could not knock them over. Dr. Meijer set up motion sensors and automatic video cameras. Several years and 12,000 snippets of video later, she and Yuri Robbers, also a Leiden researcher, reported the results. They were released online Tuesday in the Proceedings of the Royal Society B.
Sounds fair—put mice in a nice area and then trap them with familiarity. The study even turned up a few other species of animal ready to get their jog on.
As to why the mice, frogs or perhaps even slugs run, or move, on the wheel, Dr. Meijer said she thought that "there is an intrinsic motivation for animals, or should I say organisms, to be active."
The running, according to the study, was rewarding for the rodents, just like it might be if/when humans go running. Their brains responded positively to the physical activity.
Another way to look at these findings, however, is that when mice are released into the wild, they return to familiar structures and the inevitability of the rat race, like tiny rodent Sisyphuses who cannot escape their fate.