Speaker
Description
Previous research shows that pigs (Sus scrofa domesticus) are sensitive to each other’s emotional states and provide targeted aid, including helping and consolation. However prosocial behavior in pigs varies greatly across individuals and experiments. We present data from two studies indicating an important role of emotional arousal in mediating prosocial behavior. In the first study, n = 74 adolescent pigs were tested in two separation-reunion contexts. In the helping context, pen-mates could first observe and then help a trapped pig to return to the group, while in the direct-reunion, pen-mates did not receive cues from the separated pig until the reunion. In the helping context, responses satisfied criteria for consolation, while direct-reunions elicited increases in bi-directional affiliative and non-affiliative interactions with reunited pigs (GLMM, p < 0.001), who showed more anxiety behavior (GLMM, p = 0.03). In a second study, we measured helping responses to n = 219 trapped pigs, representing different breeds tested at different institutes, who first received either a high-stress or a low-stress intervention. We found site-specific differences in helping (GLMM, p = 0.04), due to differences in propensities to help pigs who had received the high-stress intervention (post-hoc Tukey, p = 0.02). The combined results suggest that emotional contagion of cues from mildly-distressed partners promotes prosocial behavior, while emotional contagion of cues from highly-distressed partners promotes prosocial reactions in some individuals while inhibiting them in others. Future work will address causes of this variation, including potential variation in capacities for emotional regulation in pigs.
