Capuchin Monkeys Display Affiliation Toward Humans Who Imitate Them

Monkey See Human Do Imitation has been put forth as one mechanism through which cultural learning occurs. Paukner et al. (p. 880; see the Perspective by Call and Carpenter) now demonstrate that imitation may also contribute to prosocial behaviors. Capuchin monkeys behaved in a more affiliative manner—as assessed by direction of gaze, physical proximity, and token exchange—toward humans who imitated them as compared to humans who performed the same movements, but did not do so simultaneously. The chameleon effect also operates in monkeys. During social interactions, humans often unconsciously and unintentionally imitate the behaviors of others, which increases rapport, liking, and empathy between interaction partners. This effect is thought to be an evolutionary adaptation that facilitates group living and may be shared with other primate species. Here, we show that capuchin monkeys, a highly social primate species, prefer human imitators over non-imitators in a variety of ways: The monkeys look longer at imitators, spend more time in proximity to imitators, and choose to interact more frequently with imitators in a token exchange task. These results demonstrate that imitation can promote affiliation in nonhuman primates. Behavior matching that leads to prosocial behaviors toward others may have been one of the mechanisms at the basis of altruistic behavioral tendencies in capuchins and in other primates, including humans.