'We were surprised': University of Michigan chimpanzee study in Africa reveals developmental similarities to human teenagers

Chimpanzees, like human teenagers, are more impulsive, risk-seeking, and less able to regulate their emotions than adults, according to a new study by researchers at the University of Michigan.

The study, which appears in the Journal of Experimental Psychology: General, examined if chimpanzees face similar psychological challenges as human teens, according to a University of Michigan press release. Researchers examined 40 chimpanzees in a sanctuary in the Republic of Congo. Both young and adult chimps were presented with two games: a ‘gambling’ task where they could either play it safe and get a specific reward or gamble on possibly getting a better payoff; and a delay of gratification task where they could choose between a smaller reward they could have right away, versus a larger reward they had to wait one minute to access.

In both tasks, researchers collected saliva samples to track everyone’s hormone levels and measured the chimpanzees’ emotional reactions to their choices by tracking if the primates scratched themselves or made an emotional vocalization (like a child whining). The results showed that younger chimpanzees were more risk-prone than adults, but they were similarly successful at waiting for delayed rewards. Yet younger chimpanzees were more likely than the older chimpanzees to get emotional while they were waiting for the bigger reward.

“This means they are very similar to us in terms of how they experience a long developmental period, unlike many other animals who grow up much more quickly,” said the study’s lead author, Alexandra Rosati, University of Michigan associate professor of psychology and anthropology. “We were surprised to find that younger chimpanzees were just as able to forgo the temptation of immediate rewards and wait for bigger future payoffs as were adults.

The study’s co-authors were Melissa Emery Thompson, University of New Mexico; Rebeca Atencia, Jane Goodall Institute Congo; and Joshua Buckholtz, Harvard University.