but — in the millions of years that encompass their evolutionary history, bonobos have remained virtually unchanged. They are still hairy, quadrupedal, bitsy-brained and barking. They still live in the jungles of Africa. Not a single bonobo, or its close relative the chimpanzee, has ever taken a step out of Africa the way that members of our species did some 60-100,000 years ago. In fact, not a single bonobo or chimpanzee has ever ventured across national borders within the continent to explore new opportunities or develop new cultures. Not a single bonobo or chimpanzee has even moved out of the forests and on to the beaches or deserts or alpine environments of Africa. Not one. When we took our steps out of Africa, we did so with confidence, ready to tackle new environments, create novel tools, engage in rituals to commemorate the dead, build fires to cook food and keep warm, join hands with unrelated strangers in the service of cooperation, and create oral histories that could be passed on to generations of children. What enabled this celebratory migration was a cerebral migration. Not only did our brain get much bigger than the one housed within bonobo and chimpanzee skulls, it evolved into an engine that generates an unlimited combination of thoughts and feelings. We uniquely evolved a promiscuous brain. What does promiscuity buy? In a word: “creativity.” It enables regions of the brain that evolved for highly specialized functions to intermingle with other regions of the brain to create new ways of thinking and new ways of experiencing what we see, hear, touch, taste and feel. A promiscuous brain paved the way for awe-inspiring bursts of creativity in art, music, literature and science. A promiscuous brain enabled Bach and Bono, Picasso and Pollock, Shakespeare and Shaw, and Descartes and Darwin. A promiscuous brain enables us to imagine things we have never directly experienced, to create once unimaginable worlds, including blissful heavens and living hells. M