The evolutionary roots of prosociality: the case of instrumental helping.

Comparative studies with closely related primate species are crucial to understand the origins of human prosociality. One type of prosocial behaviour that probably relies on evolutionary ancient skills and motivations is instrumental helping. Recent experimental studies have shown that bonobos and chimpanzees will help others achieve their action goals. Chimpanzees have shown to help others picking up and giving objects to a recipient, opening locked doors for conspecifics struggling to open them, and releasing stuck rewards that recipients were trying to reach. Recent studies have now replicated some of these results with bonobos. However, whereas chimpanzee's helping emerges mainly in response to recipients' signals of need, bonobos also help proactively. This difference could rely on bonobos' enhanced socio-cognitive skills.