Among chimpanzees, peeing is contagious
This is the first known case of copycat urination
Chimps at a sanctuary in Japan (some shown) have a surprisingly contagious bathroom behavior.
Kumamoto Sanctuary
Hate waiting in line for the bathroom? Chimpanzees have a social solution: Everyone go at once.
A study now shows that among chimps, peeing is contagious. It’s “the first study to investigate contagious urination in animals,” says Shinya Yamamoto. He studies animal behavior at Kyoto University in Japan.
His coworker, Ena Onishi, was first to get an inkling of this contagious tinkling. She, too, studies animal behavior at Kyoto University. And she spotted something odd while watching a group of captive chimps.
“I noticed a tendency for [them] to urinate at the same time,” she says. Onishi then wondered if peeing — like yawning and grooming — is contagious in these animals.
To find out, she and some coworkers spent more than 600 hours studying 20 captive chimps. These animals lived at the Kumamoto Sanctuary in Japan.
The team observed chimpanzees peeing more than 1,300 times. And the chimps were likely to pee together, these data revealed. If one chimp was near another that was peeing, it was more likely to start.
The researchers shared the new findings January 20 in Current Biology.
What causes group peeing?
This contagious peeing didn’t seem to depend on social closeness. That is, peeing was contagious among chimps that knew each other well and ones that didn’t. That was a surprise. It’s different from the species’ copycat grooming and yawning. In those cases, chimps that are socially closer are more likely to mimic such a behavior.
Contagious peeing instead was related to rank. Low-ranking chimps were more likely than others to start peeing if a nearby chimp did. “This was an unexpected and fascinating result,” Onishi says. And it might happen for a couple of reasons.
High-ranking chimps might influence the urination of others, she says. Or low-ranking chimps may just be more aware of others in social settings. As a result, they may be more likely to respond to others’ behaviors. That just might happen to include peeing.
Further research could show if contagious peeing is useful to chimpanzees in some way, says Zanna Clay. She’s a psychologist at Durham University in England. She did not take part in the new research. But she has studied the contagious nature of chimp grooming and play.
Onishi next wants to study other groups of chimps, including wild ones. That may reveal how factors like sex and age may play a role in this behavior, she says. Scientists could also see if other species, such as bonobos, show such contagious urination.
