One Chimpanzee Urinates, Everyone Follows... Contagious Like a Yawn

Japanese Researchers Focus on Chimpanzees Urinating Simultaneously
Over 600 Hours of Observation on Urination Behavior
Lower Social Rank Leads to More Imitation... "Contagious Urination"

A study has found that urination, like yawning, can be contagious among groups of chimpanzees. On the 20th (local time), the British Daily Mail reported, "Researchers from Kyoto University in Japan discovered that chimpanzees are more likely to urinate after seeing another nearby chimpanzee urinate."

Chimpanzees in the Kumamoto Wildlife Sanctuary, Japan. Kumamoto Sanctuary Homepage

The researchers focused on the fact that chimpanzees in a protected area in Kumamoto, Japan, often urinate almost simultaneously, investigating whether this behavior is similar to contagious yawning. Previous studies showed that in pygmy chimpanzees, when one chimpanzee yawns, others yawn within a minute regardless of their relationship. There is also research indicating that 90% of people yawn when someone close to them yawns.

After observing and analyzing the urination behavior of 20 chimpanzees for over 600 hours, the researchers found that the chimpanzees' urination was much more synchronized than expected. In particular, the closer the physical distance to the chimpanzee that urinated, the higher the likelihood of following the urination.

Hierarchy within the group also influenced urination. Chimpanzees with lower social status were more likely to imitate the urination of others. The researchers explained, "In chimpanzee groups, urination behavior tends to flow downward influenced by hierarchy."

The researchers named this phenomenon "contagious urination." However, unlike yawning, contagion was not more pronounced among socially closer individuals. Dr. Ena Onishi, who led the study, said, "Initially, we expected social closeness to affect contagiousness as with yawning, but we found no evidence for this. Instead, we observed a clear influence of social rank." She added, "More research is needed to understand the specific functions and mechanisms of contagious urination," and expressed curiosity about whether this phenomenon occurs in other species as well.