How normal is aggressive behavior? And at what level of violence can it no longer be classified as normal? Questions like these arise in the wake of events such as the mass shooting in Norway in July 2011, where an individual killed over seventy people. Or in the case of the youth riots in London a few weeks later, when shops were looted, houses were burned down, and people were threatened. Is this the release of a primal instinct or a reaction to adverse life circumstances? Recent neurobiological research contradicts Freud's theory of mere human drives and emphasizes that aggression generally requires a trigger. This could be a physical attack, humiliation, or a socially degrading situation. Thus, aggression is primarily a reaction. Learn about aggression and the various theories surrounding it with this book!.