How to make friends with a monkey

Posted by Emma Woollacott

Washington, DC - It's well-known that mirroring the posture and behaviour of others predisposes them to like you. And apparently the same phenomenon holds true for monkeys.

A team of scientists at the National Institutes of Health and two Italian research institutions have found that capuchin monkeys preferred the company of researchers who imitated them to that of researchers who didn't.

 The monkeys not only spent more time with their imitators, but also preferred to engage in a simple task with them even when provided with the option of performing the same task with a non-imitator.

"Researchers have known that human beings prefer the behavior of other people who subtly imitate their gestures and other affects," said Duane Alexander, Director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. "Observing how imitation promotes bonding in primates may lead to insights in disorders in which imitation and bonding is impaired, such as certain forms of autism."

Apparently, it's the first time anyone has established this - although you might think that the fact that "to ape" is a synonym for "to copy" would have provided a clue.

Each monkey was given a wiffle ball. They commonly displayed three behaviors: poking the ball with their fingers, putting it in their mouths, or pounding it on a surface.

In sequence, each monkey was paired with two human investigators, each of which also had a wiffle ball. One investigator would mimic the monkey’s behavior, poking, mouthing, or pounding the ball, as appropriate. The other investigator would adopt a different behavior, for example, pounding the ball when the monkey poked it. (It must have been entertaining to watch.)

Afterwards, the monkeys consistently spent more time near the investigator who imitated them than with the investigator who did not. They also consistently chose to accept a reward from an imitator rather than a non-imitator.

Wild capuchin monkeys have been observed to match each other's behaviors when feeding, traveling, or avoiding predators.

"It has been argued that the link between behavior matching and increases in affiliation might have played an important role in human evolution by helping to maintain harmonious relationships between individuals," the authors wrote. "We propose that the same principle also holds for other group-living primates."

The study appears in Science.