Among chimpanzees, thrill-seeking peaks in toddlerhood

Toddlers are the daredevils of the chimp world.

Chimps ages 2 to 5 are more likely than older chimps to free-fall from tree limbs in the forest canopies or leap wildly from branch to branch, researchers report January 7 in iScience. Past age 5, those dangerous canopy behaviors decrease by roughly 3 percent each year.

Among humans, teens are the real daredevils. They are, for instance, more likely than other children to break bones and die from injuries. But human toddlers might behave as recklessly as chimp toddlers were it not for parents and caregivers putting the kibosh on all the fun — and broken bones, says biologist Lauren Sarringhaus of James Madison University in Harrisonburg, Va. “If humans scaled back their oversight, our kids would be way more daredevilish.”

Humans and chimpanzees show markedly different caregiving patterns, say Sarringhaus and others. Chimp moms largely parent alone. Dads don’t help. Nor, typically, do grandmothers, older siblings or other group members. Chimpanzees cling to their moms for the first five years of life, but by age 2 or so, they begin to explore more independently. Moms can’t readily help kids swinging high up in the air.

By comparison, the presence of alloparents, or caregivers beyond the parents, are a defining feature of human groups, Sarringhaus says. In modern times, alloparents have come to include teachers and coaches for a plethora of supervised after-school activities. Nowadays, many developmental experts in the Western world have been decrying the rise of intensive or helicopter parenting in which kids spend less time unsupervised and playing outside than those in generations past.

“It’s a really exciting avenue of research of how caregiving influences risk-taking behavior. There’s not a lot of research out there addressing this point,” says Lou Haux, a psychologist and primatologist at the Max Planck Institute for Human Development in Berlin, who was not involved with the study.

Sarringhaus and her team recorded over 100 chimpanzees ranging in age from 2 to 65 as they swung through the tree canopy. The chimps are part of the Ngogo Chimpanzee Project in Uganda’s Kibale National Park. The researchers then quantified how often each member lost contact with tree branches, whether by falling to a lower branch or leaping across a gap to another branch.

Chimpanzees ages 2 to 5 were three times as likely as adult chimpanzees (15 and older) to attempt such death-defying maneuvers. Chimp “teens,” ages 10 to 14, were no chumps either, engaging in such behaviors twice as often as adults.

Risky maneuvers in the canopy come with a tradeoff, though. Roughly a third of chimpanzees show evidence of previous bone fractures, other research shows. But with their malleable bones and lighter weights, smaller chimps — and humans — are less likely to suffer grave injuries from falls than larger ones, making toddlerhood an ideal time for dangerous exploration.

“My goal is not for this to lead to parenting advice,” Sarringhaus says.

Instead, Haux says, this sort of research helps put the intensive parenting observed in Western countries today in broader perspective. “We try to build a very safe space around our children…. How did all this evolve?”