Whether or not we know it, our daily lives are shaped by powerful current of instinct. The conscious and unconscious decisions we make are deeply affected by an ancient and universal genetic programme. Our ambition and lust, our drives to compete and to co-operate are essential components of the human mind, forged among our ancestors on the African savannah. Instincts were instrumental in the evolutionary success of the species, and success meant a fondness for sex and violence, for status and wealth - and a will to survive. From ordering lunch to one night stands, human behaviour is still heavily influenced by this genetic agenda. But how well do instincts equip us for the 21st century? Do instincts help or hinder us as we deal with large anonymous cities, low-level stress, the battle of the sexes, and the fracturing of communal life?