Chimpanzees help others with what they want; children help them with what they need.

Humans, including young children, are strongly motivated to help others, even paying a cost to do so. Humans' nearest primate relatives, great apes, are likewise motivated to help others, raising the question of whether the motivations of humans and apes are the same. Here we compared the underlying motivation to help in human children and chimpanzees. Both species understood the situation and helped a conspecific in a straightforward situation. However, when helpers knew that what the other was requesting would not actually help her, only children gave her what she needed instead of giving her what she requested. These results suggest that both chimpanzees and human children help others but the underlying motivation for why they help differs. In comparison to chimpanzees, young children help in a paternalistic manner. The evolutionary hypothesis is that uniquely human socio-ecologies based on interdependent cooperation gave rise to uniquely human prosocial motivations to help others paternalistically.

Chimpanzees' (Pan troglodytes) internal arousal remains elevated if they cannot themselves help a conspecific.

Chimpanzees help conspecifics achieve their goals in instrumental situations, but neither their immediate motivation nor the evolutionary basis of their motivation is clear. In the current study, we gave chimpanzees the opportunity to instrumentally help a conspecific to obtain food. Following recent studies with human children, we measured their pupil diameter at various points in the process. Like young children, chimpanzees' pupil diameter decreased soon after they had helped. However, unlike children, chimpanzees' pupils remained more dilated upon watching a third party provide the needed help instead of them. Our interpretation is that chimpanzees are motivated to help others, and the evolutionary basis is direct or indirect reciprocity, as providing help oneself sets the conditions for a payback. This is in contrast to young children whose goal is to see others being helped-by whomever-presumably because their helping is not based on reciprocity. (PsycInfo Database Record (c) 2021 APA, all rights reserved).