In this timely collection, biological and behavioral scientists address questions emerging from new research about the origins and interconnections of altruism and aggression within and across species. They explore the genetic underpinnings of affiliative and aggressive orientations as well as the biological correlates of these behaviors. They consider environmental variables--family patterns, childrearing practices--that influence prosocial and antisocial behaviors. And they examine internal processes such as empathy, socio-inferential abilities, and cognitive attributions, that regulate...