Can animal models provide insights into human empathy and promote nurturance? There is a growing recognition of how animals respond to the affective states of other animals (1, 2), including the show of empathy, a state once thought to be unique to primates. On page 1427 of this issue, Ben-Ami Bartal et al. (3) demonstrate that captive rats controlled experiments act prosocially to help other rats, even when they receive no explicit social rewards. This raises questions about the affective experiences of animals other than humans.
