Back in 2014, NASA sent 20 mice to the International Space Station, dividing them into young and old age groups. The young mice began to run around the habitat walls in circles within 9 to 11 days of launch. They ran as a collective and appeared to be well-coordinated with one another. In contrast, the older mice were floating in the same environment but did not seem to care about the exercise at all. Researchers have proposed several possible explanations for this behavior, but none has been confirmed.
