The Social Leap: how and why humans connectOur chimpish ancestors were superbly adapted to a life of leaping through the trees. To survive on the savannah, they had to make a social leap a change that drives us still today. Human psychology is rife with contradictions. We work hard to achieve our goals, but when we succeed, our happiness is fleeting compared with our efforts. We hope our friends will do well in life, but can't help feeling jealous if they do too well. We're aghast at the