A study published Wednesday in Proceedings of the Royal Society B: Biological Sciences has gifted us with a piece of information that deserves only one response: "Thank you, internet!" It turns out our pet hamsters are not alone in their love of exercise wheels. Wild animals like to run on them too.
The study's authors, self-proclaimed 'exceedingly curious' scientists Johanna H. Meijer and Yuri Robbers of Leiden University wanted to better understand how giving wheels to lab animals affects their health – and more specifically, if wheel running is a natural behavior or simply a compulsion that develops in captivity.
"I have the proverbial curiosity of a cat,” Robbers says. "This started when I was very young. As soon as I could read I became a voracious reader, and an equally voracious experimenter. I always wanted to find out more about my surroundings. Whether it was reading about space travel … or blowing up all of the fuses in the house, I was eager to find out more."
In order to get to the bottom of the wheel-running mystery, they turned to one of our favourite research tools ... camera traps.
A small wheel was placed in an outdoor cage, with an opening large enough for small animals to access it. The team fitted the cage with motion sensors and camera equipment, as well as with a food tray to attract anything lurking nearby.
Here's the kicker: over 200,000 animals, including mice, shrews, rats, frogs and slugs, stopped by for a wheel-running rendezvous over a period of three years – and many of them came back for seconds.
"This observation indicates that wheel running may well be intentional for these animals," the authors say.
Even though the non-rodent animals each accounted for less than one percent of total time spent running (mice accounted for about 88 percent), we can’t get enough of watching them do it.
"I had to laugh about the results," Meijer says. "But at the same time, I take it very seriously. It's funny and it's important."
Your first instinct might be to assume the animals were simply drawn to the wheel by the sweet aroma of free food (which we admit makes sense). And the study's results do indicate that the number of visits to the recording site decreased when no food was present. But without food, more visitors engaged in running during their time spent in the cage.
The authors explain that this suggests that running itself may be rewarding for mice – an important thing to consider when designing and evaluating lab setups.
"In a time when ... lack of exercise in particular [is] a major cause of disease in the modern world, research into physical activity is of utmost importance. Our findings may help alleviate the main concern regarding the use of running wheels in research on exercise," they say.
Reproduction
