Peeing Like A Leader: What Chimpanzees Teach Us About Social Dynamics

According to the study’s lead author this behaviour may reveal evolutionary roots in social bonding.

Chimpanzees have more in common with us than we ever imagined, even in the bathroom department. Photo Credit: AFP

Think yawning is the only contagious behaviour? Think again. In a recent study, researchers from Kyoto University have discovered that chimpanzees are more likely to urinate when they see others doing it. And it’s not just random—it’s all about power and rank.

According to the study’s lead author, Ena Onishi, this behaviour may reveal evolutionary roots in social bonding. “In humans, urinating together can be seen as a social phenomenon,” she explained. Cultures worldwide reflect this idea, from the Italian proverb, “Whoever doesn’t pee in company is either a thief or a spy,” to the Japanese term “Tsureshon,” which refers to group peeing.

Scientists started the study after observing that chimps at Japan’s Kumamoto Sanctuary appeared to urinate in unison. Inquisitive, they examined more than 1,300 toilet excursions across 600 hours of video. The outcomes? Urination was not haphazard. Chimpanzees who were nearer to someone who had just urinated were much more likely to do the same.

But here’s the twist: lower-ranking chimps were the most likely to join the peeing parade. Onishi explained, “We observed a clear influence of social rank, with lower-ranking individuals more likely to follow the urination of others.”

Co-author of the study, Dr. Shinya Yamamoto, described the findings as “unexpected and fascinating.” He suggested it could point to hidden leadership within the group or even strategies for strengthening social bonds. “These behaviors might reflect attention bias, group synchronisation, or even subtle ways to reinforce social order,” he said.

The study also suggests practical purposes. Chimps may empty their bladders as a group before long-distance travel, much like humans do. And while urination as a social cue has been well-observed in humans, this is the first time it’s been documented scientifically in animals.

Published in Current Biology, the research raises big questions: Could this behaviour exist in other species? Is peeing together a subtle form of communication or even leadership? For now, what’s clear is this: when it comes to social dynamics, even something as basic as urination carries profound meaning.