A new study published in Current Biology has found that chimpanzees at a Japanese sanctuary exhibit a behavior known as “contagious urination,” where they are more likely to relieve themselves when others around them are doing so. Researchers believe this phenomenon may have deep evolutionary roots, similar to how yawning can trigger others to follow suit.
In Japan, there is an Italian proverb that says “Whoever doesn’t pee in company is either a thief or a spy.” This behavior is also referenced in art across cultures and continues to appear in modern social contexts. Researchers studied the phenomenon after noticing that many chimps at the sanctuary seemed to synchronize their peeing habits.
The study, led by Kyoto University’s Ena Onishi, involved filming 20 captive chimps over 600 hours, documenting over 1,300 “urination events.” The results suggest that this behavior is hierarchical, with dominant chimps triggering the others. The findings provide new insights into the evolutionary roots of human social behaviors and challenge existing understanding of contagious urination in humans.
Source: https://arstechnica.com/science/2025/01/peeing-is-contagious-among-chimps