When ya gotta go, ya gotta go, and if it sometimes seems like the urge to pee seems more pressing when others nearby are letting loose—well, there’s now a bit of science to back that up. It turns out that humans may not be the only species to experience “contagious urination,” according to a new paper published in the journal Current Biology. Chimpanzees living at the Kumamoto Sanctuary in Japan are also more likely to relieve themselves when others are doing so nearby, and the behavior seems to be hierarchical, “flowing down” from dominant chimps to more passive ones.
“In humans, urinating together can be seen as a social phenomenon,” said coauthor Ena Onishi of Kyoto University. “An Italian proverb states, ‘Whoever doesn’t pee in company is either a thief or a spy’ (Chi non piscia in compagnia o è un ladro o è una spia), while in Japanese, the act of urinating with others is referred to as ‘Tsureshon’ (連れション). This behavior is represented in art across centuries and cultures and continues to appear in modern social contexts. Our research suggests that this phenomenon may have deep evolutionary roots.”
Onishi, et al decided to study the phenomenon after noticing that many chimps in the sanctuary seemed to synchronize when they peed, and they wondered whether the phenomenon might be similar to how one person yawning can trigger others to follow suit—another “semi-voluntary physiological behavior.” There had been no prior research into contagious peeing. So they filmed the 20 captive chimps over 600 hours, documenting over 1,300 “urination events.”