Capuchin monkeys living in Brazil. [Image courtesy of Elisabetta Visalberghi]
An old adage holds that imitation is the highest form of flattery, and new research published in Science finds that some monkeys appear to feel the same way. The study seems to prove capuchin monkeys appreciate it when humans imitate their actions—and that they often repay that imitation with their friendship.
During a series of experiments with the highly social capuchins, researchers discovered that they much preferred humans who imitated their actions immediately, compared with other humans who performed similar actions as the monkeys, but not at the same time.
Since imitation has long been associated with cooperative behavior among humans—and since it provides a way to connect with others and communicate likeness or affinity—this discovery of a link between imitation and friendly social behavior in non-human primates suggests that imitation could be an underlying mechanism of productive social behavior in all primates, including humans.
Annika Paukner from the National Institutes of Health Animal Center in Poolesville, Maryland, along with colleagues in Italy, performed this series of studies with the capuchins.
"Observational and experimental evidence suggests that capuchins are easily influenced by others' behavior, and are thus likely to recognize when others display behaviors matching their own actions," Paukner writes in the 14 August issue of Science. "Moreover, because capuchins are strongly bonded into social groups, they may share with humans this mechanism to facilitate social group living; namely, increasing affiliation toward those who display matching behaviors. We investigated whether capuchins recognize imitation and whether imitation positively affects capuchins' social interactions."
The researchers found that the monkeys looked much longer at their human mimics, spent more time near them, and also interacted with them more often in a token-for-food exchange—compared to how they responded to other humans who weren't directly imitating them.
Through a series of follow-up experiments, the researchers also confirmed that it was, in fact, the human act of imitation that gained the capuchin's affection, and not simply increased familiarity or perceived attentiveness to the monkeys.
"Matching or coordination of behaviors may lead to higher levels of tolerance and affiliation as well as decreases in aggressive behaviors, thereby increasing group cohesion," Paukner writes. "Behavior matching can therefore be regarded as a type of 'social glue,' helping to bind individuals together."
Since their studies were all performed in a laboratory, the researchers recognize that more thorough data on this phenomenon is needed from the capuchins' natural group environments in the wild. However, it is already known that wild capuchins often synchronize their behavior for certain tasks, like traveling, feeding, and predator defense.
"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," Paukner and her colleagues say. "We propose that the same principle also holds for other group-living primates."