Capuchin monkeys are not prosocial in an instrumental helping task

Comparative research can shed light on the evolutionary roots and cognitive underpinnings of prosocial behavior by revealing not only positive instances of prosocial motivations in other species, but also the boundary conditions of these motivations. To explore factors that may constrain prosocial behavior, we examined whether brown capuchins (Cebus apella), which demonstrate regard for the welfare of conspecifics in other contexts, would behave prosocially in a minimal-cost instrumental helping task. We observed that when given the opportunity to share tokens that allow a conspecific to obtain food from an apparatus, capuchins showed no regard for another individual's welfare. Subjects transferred tokens to an adjacent chamber when the apparatus was present, but did so just as often when the chamber was empty as when there was a recipient present to obtain food. While capuchins are sensitive to others' welfare in some contexts, the current results suggest that they do not spontaneously produce goal-specific helping actions on behalf of a conspecific. The lack of regard for others exhibited in this context provides insights into the factors that may constrain prosocial behavior in capuchins and other primate species.