We evolved to have a profound sound acuity. This was a must if our species was to survive in the jungles and the savannahs by protecting ourselves from predators and enemies and finding food and safe shelter. Being attuned to the natural world meant not only seeing things but hearing them. At night, seeing with our ears, building a spatial perception of our surroundings unaided by images, was a matter of life or death. Our ancestors could reconstruct a whole environment — the kinds of animals, the direction of the wind, if water was near or far, the weather patterns — by quietly listening.