Finding a balance between cooperative or prosocial behavior – such as social bonding and empathy – and conflict – or competitive-aggressive, self-interested behavior – is the fundamental challenge to the operation of societies and to the behavior of individuals in a social setting. But how do these apparent opposites relate to one other? As would many social or behavioral scientists, we initially approached this with the idea that they are two separate functions that need to be balanced against each other to varying degrees to construct a functioning social entity, and to some extent this holds true. But independently of one another, the contributing authors to this volume advanced a more sophisticated view of the relationship; that the poles of social interaction are in fact interconnected to the extent that what we view as antisocial or aggressive behavior are fundamental to establishing and maintaining positive or prosocial behavior within groups or individuals.