Monkey See, Monkey Do, Monkey Like

14 August 2009
Posted by Chris Smith.

Capuchin monkeys prefer humans who imitate them over those that do not, according to research published in Science this week.

"We often unintentionally imitate the body postures, gestures and mannerisms of our social interaction partners," according to Annika Paukner from the National Institutes of Health Animal Centre in America, who led the study along with colleagues in the US and Italy.  When someone imitates us, we like them more, empathise with them more and are even likely to be more generous to them.  Imitation clearly plays an important role in inter-personal relationships and social existence, and is thought that the ability to make strong social bonds have an evolutionary advantage over social rejects.  If that is the case, it could also be true for non-human primates, such as capuchin monkeys.

To determine if this is the case, Paukner and colleagues tested whether capuchins recognise imitation, and if this leads to a change in social interactions.

Capuchin monkeyTo determine if the monkeys could tell the difference between someone directly imitating them compared with someone doing something merely similar, both the monkeys and the experimenters were given a ball.  One experimenter then imitated the capuchins directly, while the other just played with the ball in a way similar to normal capuchin behaviour.  The monkeys paid significantly more attention to the imitator, indicating that they are sensitive to imitation.  In another experiment, the monkeys chose to be closer to the imitator than a non-imitating experimenter, another indication of a developing affiliation.

Knowing that the capuchins responded positively to imitation, a token exchange experiment was set up.  This relies on social interaction between monkey and experimenter, as the monkey must present a token in exchange for some food.  The monkeys were significantly more likely to approach the experimenter who had imitated them, despite having shown no preference before the experiments began.

According to Paukner, "These experimental results demonstrate that imitation significantly affects the behaviour of capuchin monkeys", and warrants further study to see if similar effects are seen in the wild.  As imitation is seen far more often in humans than in other ape species, observing the effects in non-human primates could help to understand how imitation has acted as a 'social glue' throughout our evolution, and could be an underlying mechanism of protective social behaviour in all primates.

In a related 'Perspectives' article, Josep Call and Malinda Carpenter explain that imitation could be communicating a different type of social information, such as dominance structure.  If this is the case, the experimenter who is imitating the primates may make himself or herself more approachable not through building affiliation, but by a reduction in social status - The capuchins may then appear to be affiliated merely because they are less fearful.

Either way, it offers a tantalising glimpse into our world as "the ape who apes".

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