As parents and educators struggle to understand the often reckless behavior of human teenagers, a new study has shed light on the age-old nature versus nurture debate. Researchers at the University of Michigan have found that adolescent chimpanzees exhibit some of the same risk-taking behavior as human teens, but may be less impulsive.
The study, published in the American Psychological Association, involved 40 wild-born chimpanzees at a sanctuary in the Republic of Congo. The chimpanzees voluntarily participated in two tests involving food rewards, and their emotional reactions and vocalizations were recorded, along with saliva samples to track hormone levels.
In the first test, adolescent and adult chimpanzees were presented with a choice between a container with peanuts, a food they somewhat liked, or a container that concealed either an unliked food (cucumber) or a favorite food (banana). The adolescent chimpanzees took the risky option more often than adult chimpanzees, but both groups had similar negative reactions when they received cucumber.
The second test, modeled after the famous “marshmallow test” with human children, examined the chimpanzees’ ability to delay gratification. Both adolescent and adult chimpanzees chose the greater delayed reward at a similar rate, but adolescent chimpanzees threw more tantrums during the one-minute delay than adult chimpanzees.
Lead researcher Alexandra Rosati, PhD, said, “Adolescent chimpanzees are in some sense facing the same psychological tempest that human teens are. Our findings show that several key features of human adolescent psychology are also seen in our closest primate relatives.” The study suggests that risk-taking behavior in both adolescent chimpanzees and humans appears to be deeply biologically ingrained, but increases in impulsive behavior may be specific to human teens.