By Ed Cara Published January 21, 2025 | Comments (0) | Chimpanzees at the Kumamoto Sanctuary holding orange slices. Kumamoto Sanctuary It looks like humans arent the only ones who occasionally go the bathroom in groups. A study out this week shows that peeing can sometimes be contagious among chimpanzees, too. Scientists at Kyoto University in Japan led the research, which was published Monday in the journalCurrent Biology. They observed captive chimpanzees living at the Kumamoto Sanctuary for hundreds of hours, noticing that when one chimp decided to pee, others would often follow suit. This phenomenon might be shaped by the social hierarchy of our primate cousins, the researchers say. As is often the case in science, lead researcher Ena Onishis inspiration to conduct this study came unexpectedly. While observing a group of captive chimpanzees as part of a different research project, I noticed a tendency for individuals to urinate at the same time. This resemblance to certain human behaviors piqued my curiosity, Onishi, a doctoral student at the Kyoto University Wildlife Research Center, told Gizmodo. In Japan, there is a specific term called Tsureshon (), which refers to the act of urinating in the company of others. Starting from there, I developed my research question, wondering if this might be one of the contagious phenomena, like contagious yawning or contagious scratching, and decided to investigate whether contagious urination existed. Onishi and her team studied the Kumamoto Sanctuary chimpanzees for more than 600 hours, ultimately documenting 1,328 urination events. They found that the chimps generally tended to pee more often after a fellow chimp had just peed. But there were certain patterns to this contagious urination.For one, a chimp was more likely to pee if they were closer in proximity to the original leaker (the researchers classified three levels of proximity: within arms reach, within 3 meters, and more than 3 meters). But social class also appeared to influence the odds of a chimp peeing after another. [We] found that lower-ranking individuals were more likely to follow others in urinating. This further supports the idea that urination has a contagious and socially influenced component in chimpanzees, Onishi said. By contrast, the researchers found no evidence that a chimps social closeness to another affected their odds of contagious peeing.The findings are based on a small sample size of a single chimp population, so more research will be needed to confirm whether this is a widespread behavior among chimps everywhere, including those in the wild. And at this point, the researchers only have hunches as to why contagious urination might be common to chimps. Its possible that the behavior promotes group cohesion by ensuring that chimps are more likely to have the same shared physiological state, for instance, Onishi said. The act of positively mimicking a fellow chimp might also itself strengthen bonds between them. Or group peeing could have emerged as an anti-predator strategy, since it might reduce the risk of other animals tracking the chimps through dispersed urine odors. Whatever the reason, the researchers have plenty of peeing-related mysteries left to uncover.There are so many things wed like to learn in the future. For instance, we want to observe other chimpanzee groups to explore how social factors like sex, familiarity, and age might influence contagious urination, Onishi said. Were also curious about how this phenomenon plays out in natural settingssuch as whether it serves as preparation for long-distance travel. Since people will sometimes pee together due to their closeness with one another, there do seem to be some inherent differences in the nature of group peeing between humans and chimpanzees, the researchers say. And that raises the question of whether other primates have their own unique version of contagious urinationanother question that the researchers hope they and others can explore.Apes have a wide variety of social structures and dynamics, study researcher Shinya Yamamoto, who is studying the evolution of sociality in humans and other animals at Kyoto University, told Gizmodo. These differences may also influence their decision to urinate and its contagious nature in social contexts, which should be one of the targets of future studies.Daily NewsletterYou May Also Like By Isaac Schultz Published January 7, 2025 By Ed Cara Published January 3, 2025 By Ed Cara Published July 22, 2024 ScienceBiology Some Chimpanzees Have a Bone in Their Heartand Some Humans Might, Too By George Dvorsky Published June 10, 2020 ScienceBiology Zoo Chimps Doing a Conga Line Could Teach Us How Humans Evolved to Dance By Ed Cara Published December 13, 2019 ScienceBiology How Does a Chimpanzee Eat a Tortoise? By Smashing It Like a Coconut By George Dvorsky Published May 23, 2019