Ambition, genius, thought, imagination, love, hate, greed and, above all, consciousness ourselves as alive and as part of our world--all this is somehow enabled by the brain. The brain is the person, and if it goes wrong, a person is ruined. This book is about part of what the brain does -- a role of which many of us are hardly aware, but one that has ensured, the survival of mankind. Despite famine, drought, wars, cold, infections and hostile environments, we survive as a species -- though not always as individuals. All this time, our brains have been coping with what fate throws at us -- a...

We inherit mechanisms for survival from our primeval past; none so obviously as those involved in reproduction. The hormone testosterone underlies the organization of activation of masculinity: it changes the body and brain to make a male. It is involved not only in sexuality but in driving aggression, competitiveness, risk-taking - all elements that were needed for successful survival and reproduction in the past. But these ancient systems are carried forward into a modern world. The ancient world shaped the human brain, but the modern world is shaped by that brain. How does this world, with...