Monkey see, monkey do, monkey make friends

She-Devil, a 3 week-old Capucin monkey, rests on the shoulder of her mother at the Olmense Zoo in Olmen, Belgium October 18, 2007. Humans are not the only primates that see imitation as the highest form of flattery - capuchin monkeys also have a soft spot for those who copy their behavior, researchers reported.

CHICAGO (Reuters) - Humans are not the only primates that see imitation as the highest form of flattery -- capuchin monkeys also have a soft spot for those who copy their behavior, researchers reported on Thursday in the journal Science.

In a finding that could lend insight into human disorders like autism, U.S. and Italian behavioral psychologists said capuchin monkeys not only spent more time with researchers who imitated their behavior, but when given a choice, they picked the copycat to work with over another researcher.

The findings show imitation as a kind of "social glue" shared by both human and non-human primates, the team lead by Annika Paukner of the National Institute of Child Health and Human Development, one of the National Institutes of Health wrote.

For the study, each monkey was given a Wiffle ball -- a lightweight plastic ball with holes in it. Monkeys typically poked the ball with their fingers, put it in their mouths or used it to pound on something.

Each monkey was paired up with two human researchers, one that copied their ball-handling skills, and one that did not.

When the balls were put away, the monkeys appeared to prefer the company of the like-minded ball handler. And they preferred to work with the copycat researcher as well.

When both researchers held out a small trinket, the monkeys consistently took it from the researcher who imitated the monkey, even though both offered identical treats as rewards.

Imitation has long been considered a sign of cooperation in people. Finding the behavior in non-human primates suggests it may be common to all primates, helping to build tolerance and reducing aggression, they said.

"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," Dr. Duane Alexander, director of the National Institute of Child Health and Human Development, one of the National Institutes of Health, said in a statement.