The astonishing behavior of human adolescents may seem like a unique aspect of human maturation.
But scientists believe the slapstick and bravado could be a throwback to our primate ancestors as young people reconnect to their “inner chimpanzee” during a tumultuous adolescence.
A study of young chimpanzees showed that they exhibit the same risky behaviors and mood swings as human teenagers.
“Adolescent chimpanzees kind of face the same mental storm as human teenagers,” said lead researcher Dr. Alexandra Rosati, associate professor of psychology and anthropology at the University of Michigan.
“Our findings show that several key features of human adolescent psychology are also evident in our closest primate relatives.”
Chimpanzees can live up to 50 years and experience puberty from about 8 to 15 years.
Adolescent humans and chimpanzees are looking for a risky option
Like humans, chimpanzees show rapid changes in hormone levels during puberty, begin to form new bonds with peers, show increased aggression, and compete for social status.
To find out if other aspects of their behavior mirrored human teenagers, the researchers played two games with 40 wild-born chimpanzees in a sanctuary in the Republic of Congo.
In the first test, the chimpanzees were asked to choose between a box that always contained peanuts or a box that might have either a slice of cucumber or a slice of banana inside.
The chimpanzees could play it safe and pick the peanuts, or play to win a delicious banana, risking ending up with an unappetizing piece of cucumber.
Over several rounds of the test, adolescent chimpanzees were 55 percent more likely to take a risky option than adults.
This suggests that, like human teenagers, adolescent chimpanzees will also seek out a riskier option if a greater reward is offered.
The second test tested the chimpanzees’ ability for “delayed gratification” by allowing the chimpanzees to immediately receive one slice of banana or wait one minute to receive three slices.
Risky behavior ‘biologically deeply rooted’
Human teenagers are more impulsive than adults, so they will more readily accept immediate reward.
Although the young chimpanzees delayed their reward by about the same amount as the adults, they had more tantrums per minute than the adult chimpanzees.
This suggests that, unlike humans, adolescent chimpanzees are not more impulsive than adults, but they handle losing just as well as human teenagers.
“Previous research indicates that chimpanzees are quite patient compared to other animals, and our study shows that their ability to delay gratification is already mature at a fairly young age, unlike humans,” Rosati said.
“Risk-taking, in both adolescent chimpanzees and humans, appears to be deeply rooted biologically, but an increase in impulsive behavior may be characteristic of adolescents.”
The study was published online in the Journal of Experimental Psychology: General.