Oxytocin and vasopressin drive selective prosociality
Oxytocin and vasopressin drive selective prosociality in mammals. The selective aspect refers to prosociality being specifically encouraged in the individual’s in-group, while being discouraged in the out-group. Having initially evolved for inducing maternal and paternal behavior, the two hormones seem to have been exapted for more general use. However, just like testosterone, their effects are contingent.