Capuchin monkeys appear to negatively evaluate humans who explicitly refuse to help others reports a study in Nature Communications this week. The findings provide evidence that social evaluation based on third-party interactions is not unique to humans.
In humans, acting upon information gained through ‘eavesdropping’, or ‘reputation’ starts at an early age. However, the evaluation of social traits, based on other species’ third-party social interactions has received little experimental analysis. James Anderson and colleagues place capuchin monkeys in front of two actors that interact with each other in helpful or unhelpful ways. They then study the monkeys’ readiness to accept food from the different performers. They find that the monkeys accepted food less frequently from the performers who persistently rejected another performer’s requests for help.
Although these studies were of monkeys observing human behaviour, the authors conclude that the monkeys are likely to apply these evaluations in the context of normal group life with other monkeys. They also hope that their experimental approach could play a role in gaining further insight into the evolution of social behaviours in nonhuman primates.