Humans are more impulsive than chimpanzees in adolescence

The chimpanzees -who can live up to 50 years- reach the adolescence between the ages of 8 and 15, a stage in which, like humans, they experience hormonal changes, form new bonds, become more aggressive, and compete for social status.

However, despite the fact that chimpanzee and human adolescents face the same psychological storm, the former are less impulsive than the latter, according to a study by the American Psychological Association.

The study, published this Monday in the journal “Journal of Experimental Psychology: General”addresses the age-old question of why teens take more risks: Is it the environment or the biological predisposition?

“Our findings show that several key features of human adolescent psychology are also observed in our closest primate relatives.”explains lead researcher Alexandra Rosati, an associate professor of psychology and anthropology at the University of Michigan.

The team conducted two food reward trials with forty free-born chimpanzees in a sanctuary in the Republic of Congo.

In the first, adolescent and adult chimpanzees had to choose between two containers: one always contained peanuts (one of their favorite foods), and the other could contain a disliked food (a slice of cucumber) or a favorite food (a banana slice).

The chimpanzees could play it safe and choose peanuts or take a chance and go with the choice of banana or cucumber.

The researchers recorded the emotional reactions and vocalizations of the chimpanzees, such as moans, moans, screams, banging on the table or scratching, and collected saliva samples to study hormone levels.

After repeating the test several times, they found that adolescent chimpanzees took risks more frequently than adults, and observed that the reaction of adolescents and adults was very similar when receiving the cucumber.

The second test, based on the famous “marshmallow test” with human children, examined delayed gratification: The chimpanzees could receive one banana slice immediately or wait a minute and receive three.

Adolescent chimpanzees and adults chose the larger delayed reward in similar proportions while human adolescents tend to be more impulsive than adults, making them more likely to choose the immediate reward, the study says.

“We knew that chimpanzees are quite patient compared to other animals. This study shows that, unlike humans, their ability to delay gratification is already mature at a fairly young age.”Rosati says.

Mind you, the adolescent chimpanzees weren’t happy waiting for the extra banana slices and had more tantrums during the one-minute delay than the adult chimpanzees, according to the study.

“Risk-risk behavior in both adolescent chimpanzees and humans appears to be deeply ingrained biologically, but increased impulsive behavior may be specific to human adolescents.”concludes Rosati.

(With information from EFE)