SPINNING FOR FUN

Mice really do like running on exercise wheels. That’s the conclusion of a new study that assessed whether the activity is an expression of the rodents’ natural behavior or is prompted by the anxiety of being in captivity. Because the wheel plays a role in many lab studies, scientists were concerned that its use could tarnish research results as well as raise ethical concerns. Researchers in the Netherlands monitored two test wheels, one in a backyard garden and the other among remote sand dunes. Over two years of observation, scientists recorded nearly 1,000 incidents of mice running on the wheels. (Other animals that took a spin included frogs, shrews, and slugs.) At first the sites were baited, but researchers later removed the food to ensure the activity was natural. Without bait, the visits quadrupled. The wild mice reached speeds and ran for time periods similar to lab mice. They were also frequently observed leaving and then returning to the wheel, suggesting the activity is voluntary. “It seems that they see the running as rewarding in itself,” Leiden University Medical Center researcher Yuri Robbers tells LiveScience.com, “or maybe as a form of play.”

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