Opening with an exploration of human conflict in palaeolithic times, this chapter charts the role that warfare has played in making us who we are. It portrays war, the ever-present expression of aggression, as at its root, a conflict over resources. Through an analysis of both modern and ancient war, this chapter balances the notion with the development of modern technology, showing how an increasingly complex world has still been blighted by war despite more equitable shares in resources among nations. The chapter then moves on to deal with psychological causes of aggression, with an in depth look at the psychological makeups of Hitler, Napoleon, and Genghis Khan, before offering a new perspective on how humans will be able to rise above conflict in the future.