Chimps take risks as babies—way before human teens. Here's what that tells us.

Are helicopter parents the reason kids don’t turn rebellious until their teenage years, when they finally get some autonomy? Very possible, according to scientists who recently studied the development of risky behavior in chimpanzees as a model for that of humans.

For the study, published Wednesday in iScience, University of Michigan researchers observed recordings of 119 chimps in the wilds of Kibale National Park in Uganda. They found that risky behavior—namely, recklessly flinging themselves between the branches of elevated tree canopies as they move around the forest—peaks when chimps are infants, then decreases gradually as they age, with behavior the same in both male and females.

Human children are the opposite, with many types of risky behavior peaking in adolescence, and with boys typically more likely than girls to engage in risk taking.

The work suggests it may be because human parents and caregivers are able to keep a closer eye on human babies, while chimp mothers can curtail their children’s behavior for only as long as they can keep them within arm’s reach.

“We hypothesize that a similar pattern would be exhibited in humans if oversight were relaxed earlier in childhood, as it is among chimpanzees,” notes the study.

As Laura MacLatchy, U-M professor of anthropology and co-senior author of the study, explained in a news release, “One implication of this work is that human behavior might be having a really big impact in terms of mitigating the consequences of risky physical behavior in humans.” 

The chimp infants (ages birth to 5), in fact, were three times more likely than adults to engage in risky behavior. Juveniles (ages 5 to 10) were 2.5 times more likely and adolescents (10 to 15) were 2.1 times more likely to engage in risky behavior. 

Risky physical behavior in humans is difficult to study: It’s unethical to ask people to risk hurting themselves in a lab setting, which is why it usually relies on looking at survey data.

“However, there’s not really any behavior in humans that is constant across development. For example, sky diving is not something you can legally do until you’re 18,” said coauthor and recent U-M graduate Bryce Murray. “On the other end of the spectrum, we don’t really see something like monkey bar use in adults.”

It’s why the researchers observed chimpanzees, defining risky behavior as “free flight,” when the chimps intentionally dropped from a branch, or when the chimps leapt from branch to branch while completely letting go of any support. 

“Bryce found that in fact the youngest chimps were doing all of these crazy leaps and drops, and it declined gradually as they aged. We were really scratching our heads thinking, ‘What is going on?'” MacLatchy said. “We realized that the littlest chimps were unrestricted in what they do, as soon as they were out of arm’s reach of their mom and no longer clinging and riding around on their mom.”

“Chimps just don’t have the capabilities that we do to restrict behavior,” lead author and biologist Lauren Sarringhaus said. “We’re not cooperatively rearing children, but my kids right now are in middle school, and someone is watching them and tasked with making sure they’re not doing whatever they want to do in gym class.”

And while supervision with humans isn’t just a Global North phenomenon, Murray said, it’s “definitely gotten stronger with helicopter parents over the last few decades.”