Chimpanzees seem to have a contagious need to urinate. A recent study published in the journal Current Biology on January 20 discovered that when one chimpanzee urinates, others in the group are more likely to follow suit. This behavior, known as “contagious urination,” may have deep evolutionary roots in both humans and chimpanzees, our closest relatives.
The study’s co-author and evolutionary biologist from Kyoto University, Ena Onishi, stated in a press release that in human culture, urinating together is considered a social phenomenon. Cultural references from Italy and Japan highlight the significance of this behavior in society. This act is not only represented in art across various cultures but also continues in modern social contexts.
The researchers decided to investigate this behavior further after noticing that chimpanzees in a sanctuary tended to urinate simultaneously. They wanted to determine if urination could exhibit a similar contagious aspect to yawning observed in humans.
In their study, they monitored urination patterns in 20 chimpanzees at the Kumamoto Sanctuary, observing over 1,300 instances of urination in more than 600 hours. They analyzed the data and found that urination events were significantly synchronized, indicating a contagious aspect. The likelihood of contagious urination was higher when a chimpanzee was closer to the initial urinator.
Individuals with lower ranks in the group were more inclined to urinate when others were doing so, suggesting that social hierarchy influences urination patterns. The study revealed that social rank, rather than social closeness, played a significant role in this behavior.
This unexpected finding regarding social hierarchy and urination patterns could indicate a hidden leadership structure that synchronizes group activities or reinforces social bonds. The study suggests that seemingly mundane behaviors like urination may have underlying social significance that is often overlooked.
Further research is necessary to understand the specific functions and mechanisms behind contagious urination in chimpanzees and potentially in other species.
