Is peeing contagious, like yawning? Scientists studying chimps may have the answer
More like “monkey see, monkey pee.”
Yawning isn’t the only bodily function that’s contagious. Japanese scientists have discovered that chimpanzees are more likely to urinate when they see other primates going No. 1 as well, as detailed in a study in Current Biology.
“Our results suggest that socially contagious urination may be an overlooked, and potentially widespread, facet of social behavior,” wrote the researchers, who hail from Kyoto University.
The researchers were inspired to conduct the study after observing that 20 captive chimpanzees at Kumamoto Sanctuary appeared to heed nature’s call at the same time as their fellow simians, according to a research release.
“We found that chimpanzees, our closest relatives, tend to urinate in response to the urination of nearby individuals,” said study author Ena Onishi of Kyoto University. “Our research suggests that this phenomenon may have deep evolutionary roots.” EIVIND – stock.adobe.com
While “humans across different cultures” and time periods and certain “nonhuman animals” have long been believed to ape each other’s peeing times, the theory had not yet been battle-tested — until now.
“Since there were no prior studies on contagious urination in any species, we drew parallels to contagious yawning, another semi-voluntary physiological behavior,” declared study author Ena Onishi of Kyoto University’s Wildlife Research Centre, Cosmos magazine reported.
To deduce whether urination was contagious, researchers analyzed 600 hours of video footage depicting the 20 chimps at Kumamoto. During that time, they documented more than 1,328 urination events.
Researchers recorded the number of leaks that occurred within a minute of each other and cross-referenced the results with randomized computer simulations.
Researchers hope the study will help shed light on the origin of contagious peeing in humans. Ruben Pinto – stock.adobe.com
They found that chimps indeed synchronized their pee breaks, rather than simply going with the flow at random times.
Contrary to researchers’ predictions, social closeness didn’t influence contagious urination — unlike contagious yawning, which is more commonly observed in tight-knit pairs.
Physical proximity, on the other hand, played a major role as the closer the chimps were to each other, the more likely they were to urinate in unison.
Peeing times seemed to trickle down from the top as well.
“We observed a clear influence of social rank, with lower-ranking individuals being more likely to follow the urination of others,” said Onishi.
The scientists documented over 1,328 urination events. lapis2380 – stock.adobe.com
From that, researchers deduced that peeing in tandem could be an evolutionary mechanism used to strengthen social cohesion — a group that sprays together stays together, so to speak.
“In humans, we know that our decision to urinate is influenced by social contexts that lead us to urinate simultaneously with others and that this simultaneous urination could also promote further social bonding,” study co-author Shinya Yamamoto, also from Kyoto University, told Live Science. “Our study with chimpanzees clearly shows that they share some similarities in this phenomenon, suggesting the deep evolutionary origin of contagious urination.”
Going to the bathroom in the same location also could deter predators by throwing the scent off a single pee trail, researchers posited.
More research is needed to understand the mechanism behind simultaneous urination in chimpanzees.
However, Onishi believes that by studying this habit in our closest living relatives, we can perhaps discover the origins of the behavior in humans as well.
