Chimpanzees have once again amazed scientists by exhibiting contagious "wet" behavior.

Humans and non-human animals share many social phenomena associated with group living. In simple terms, the presence of others significantly influences us, even in mundane actions—such as yawning, walking, tapping our feet, and even pupil dilation. In a recent study, researchers discovered another fascinating behavior of chimpanzees, as reported by IFLScience.

According to the lead author of the study and PhD student at the Kyoto University Wildlife Research Center, Ena Onishi, their work revealed that urination in chimpanzees is contagious. The team conducted observational research in a sanctuary and noticed that the monkeys not only exhibited contagious urination, but it was also more likely among individuals with lower dominance and those who were physically closest to the initiator of the act.

It is worth noting that contagious urination is incredibly common among humans, even earning its own Italian proverb: "he who does not urinate in company is either a thief or a spy." This behavior is also widespread in Japan and has been recognized in art and culture. As a result, researchers wondered: could something so prevalent have evolutionary roots?

During the study, the researchers observed that chimpanzees in the Kumamoto sanctuary seemed to urinate at roughly the same time. Consequently, they decided to focus more on this behavior. They conducted 600 hours of observational research, recording 1,328 acts of urination and providing them with a wealth of data to analyze.

The team's results indicate that urination acts were significantly more synchronized than one would expect if chimpanzees were simply urinating randomly. The authors also noted that contagious urination was more likely among those who were physically closest to the initiator of urination. At the same time, the researchers believe that social rank did not influence the likelihood of the behavior spreading. However, individuals with lower dominance were more likely to urinate if someone else did.

According to Onishi, the researchers are unsure why this occurs only among individuals of lower rank, but one theory suggests that higher-ranked individuals may actually influence the urination of others more often, although the researchers lack evidence for this. If true, such behavior could indicate a form of subtle leadership, where higher-ranking individuals play a role in synchronizing the group's behavior.

Another theory posits that lower-ranked individuals may have a bias in attention. In simple terms, they are more likely to notice and react to the behavior of others. A third possibility is that this could also be linked to traits associated with lower rank, such as differences in personality or a greater motivation to bond with other group members.