Abstract
Laboratory rodents are gregarious in nature and have a feeling of empathy when witnessing a familiar conspecific in pain. The rodent observers express two levels of empathic responses: empathic contagious pain (ECP) and empathic consolation (EC). Here we examined the sex and species difference of ECP and EC in male and female mice and rats. We observed no species difference in both ECP and EC, but significant species difference in general prosocial (allo-mouth and/or allo-tail sniffing) and non-social (self-grooming) behaviors. For sex difference, male mouse observers showed more allo-licking and allo-grooming behaviors toward a familiar conspecific in pain during and longer time increase in pain sensitivity after the PDSI than female mouse observers. However, no sex difference was observed in rats. Our results highlighted an evolutionary view of empathy that social animals including rodents also have the ability to feel, recognize, understand and share the other’s distressing states.