Teenagers are known to take more risks than adults. New research has found that adolescent chimpanzees too can be inclined towards taking risks similar to human teenagers. What is different, however, is that adolescent chimpanzees can be less impulsive than their human counterparts.
The study has been published in the Journal of Experimental Psychology: General.
The study examined the behaviour of adult and adolescent chimpanzees (usually ages 8-15) using two tests. All 40 chimpanzees in the study had been born in the wild. Both tests, which were conducted in a sanctuary in the Republic of Congo, involved rewards that were given based on the chimpanzees’ behaviour.
In the first test, the chimpanzees were given a choice between two containers, one of which contained peanuts, a food that chimpanzees like to a certain extent. While the peanuts were always fixed, the other container could contain any one of two food items. This could be a slice of banana (a favourite for chimpanzees) or a slice of cucumber (which the chimpanzees would not find very tasty).
For the chimpanzees, it was a gamble. If they played it safe and went for the peanuts (which were certain), they would get at least something that they liked to an extent. On the other hand, if they went for the second container, whose contents were not certain, they could either get the tasty banana slice or end up disappointed, getting only an undesirable cucumber slice.
The test, conducted over several rounds, found that adolescent chimpanzees took the risky option more often than adult chimpanzees. This was similar to the behaviour of human teens compared to adults.
This test also examined the emotional responses of the chimpanzees after their choice was revealed. They would moan, whimper, scream, or bang on the table or scratch themselves, depending on what they had got. In this respect, although they differed in their risk-taking behaviour, adolescents and adults showed similar negative reactions when they got cucumber.
In the second test, the chimpanzees were given another choice. If they wanted bananas immediately, they would get only one slice. If they were willing to wait for one full minute, they would get three slices.
Here, the chimpanzees differed from humans in terms of the comparative behaviour between adults and teenagers. Among humans, teenagers would be more likely than adults to choose the riskier option. However, among the chimpanzees, the rate of choosing the delayed reward (and the more fruitful one) was similar among adolescents and adults.
Chimpanzees are known to be patient animals.
However, even in this test, there were differences between adult and adolescent chimpanzees. Although they preferred to wait for the larger reward, the adolescents were not happy about it. They threw more tantrums than the adult chimpanzees.
The study was led by Alexandra Rosati, a psychologist and anthropologist at the University of Michigan. A press release from the university quoted her as saying: “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.”
Risk-taking behaviour in both adolescent chimpanzees and humans appears to be deeply biologically ingrained, but increases in impulsive behaviour may be specific to human teens, Rosati said.