Chimpanzees Tend To Go To The Bathroom In Groups, Which Is Similar To How We Flock to Restrooms Together

happy chimpanzee family
estima - stock.adobe.com - illustrative purposes only, not the actual chimpanzees

After noticing that chimpanzees living at the Kumamoto Sanctuary in Japan tend to pee in groups, researchers from Kyoto University decided to study this behavior. It was similar to how humans go to the bathroom together, which can be seen as a social phenomenon.

They referred to the behavior as “contagious urinations.” Since chimpanzees are the closest living relatives to humans, this social behavior could be traced back to a common ancestor.

“An Italian proverb states, ‘Whoever doesn’t pee in company is either a thief or a spy, while in Japanese, the act of urinating with others is referred to as ‘Tsureshon.’ This behavior is represented in art across centuries and cultures and continues to appear in modern social contexts,” said Ena Onishi from Kyoto University.

“Our research suggests that this phenomenon may have deep evolutionary roots. We found that in chimpanzees, our closest relatives, tend to urinate in response to the urination of nearby individuals.”

The research team documented the peeing habits of 20 captive chimpanzees over a span of more than 600 hours, which included a total of 1,328 urination events.

Then, they analyzed the observational data and compared it with randomized computer simulations to determine whether peeing among the chimpanzees was synchronized in time. They also investigated whether it was influenced by social factors or nearby individuals.

The evidence revealed that the contagious urination behavior increased with physical proximity. When chimpanzees see another chimpanzee near them peeing, they are more likely to follow suit.

Additionally, the findings suggest that urination patterns are influenced by social hierarchy, which the researchers were surprised to discover.

Initially, they expected that any social influences would resemble those seen in yawning, but they realized that was not the case.

happy chimpanzee family
estima – stock.adobe.com – illustrative purposes only, not the actual chimpanzees

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Instead, social rank played a clear role. Chimpanzees with lower dominance ranks showed a greater likelihood of peeing when others were peeing.

There are multiple interpretations for contagious urination. For instance, it could reflect hidden leadership or be important for reinforcing social bonds.

Another theory is that several chimpanzees urinating in a single location can confuse or deter predators. It lowers the risk of being tracked through scattered urine odors.

“We are greatly influenced by the presence of others, even in mundane activities,” said Onishi. “For example, in both chimpanzees and humans, behaviors like yawning, walking, rhythmic tapping, and even pupil size are known to be contagious.”

By studying contagious urination, scientists can improve their understanding of the common ancestors of humans and chimpanzees, as well as the human origin of the social custom.

Further research is needed to learn more about the specific mechanisms of contagious urination in chimpanzees and whether the phenomenon exists in other species.

The details of the study were published in the journal Current Biology.

Emily  Chan is a writer who covers lifestyle and news content. She graduated from Michigan State University with a ... More about Emily Chan

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