Surely one of the most charming sights is of an adult struggling to reach an object, only for a toddler to pick up that object and hand it to the adult, as research has shown they so often will. Psychologists think such ingrained altruism has evolved as a consequence of our species' dependence on group living for survival. Supporting this account, Harriet Over and Malinda Carpenter have shown that subtle exposure to the sight of two apparently companionable dolls, stood side by side, is enough t