Just like humans, chimpanzees considered smarter are usually those better at exerting self-control, U.S. researchers said Thursday.
The study, published in the U.S. journal Current Biology, was the first of its kind to examine the relation between general intelligence scores and delayed gratification abilities to receive a better reward later in chimpanzees.
"The fact that this link between self-control and intelligence exists in species other than humans may demonstrate an evolutionary basis for the role that willpower plays in general intelligence," lead author Michael Beran of the Georgia State University said in a statement.
"Future research could clarify whether the relationship also exists in other primates and even non-primate species."
The research finding related back to the famous "marshmallow test," an experiment originally performed at Stanford University in the 1960s.
In the test, children were given the choice of taking a small, immediate reward of a single marshmallow placed in front of them or waiting to earn a larger reward of two marshmallows.
Previous research has found that children who performed well on the marshmallow test and other tests of delayed gratification tended to also perform well on tests of general intelligence.
Beran and colleagues found the same link existed in chimpanzees.
In their study, chimpanzees performed the Hybrid Delay Task, which tracks how often chimpanzees choose to wait for a larger, better reward rather than taking a smaller reward right away.
It also measured how well the chimpanzees managed to wait during the delay period, when there is a constant temptation to capitulate and accept the smaller reward.
The chimpanzees then completed the Primate Cognitive Test Battery, a test of general intelligence that measures a variety of individual social and cognitive factors, such as the capacity to follow pointing gestures.
Those chimpanzees who showed the highest levels of generalized intelligence were also the most efficient in the delayed gratification test.
Intelligence scores were related not only to how often chimpanzees chose to try to wait for the better reward, but also to how well the chimpanzees could wait when they chose to do so.
"In short, more intelligent chimpanzees have better self-control abilities," the researchers wrote in their paper. "This strongly suggests that self-control and intelligence have a common, but as of yet unidentified, neurobiological foundation within chimpanzees."
