Can Evolution Explain Beauty?

A male flame bowerbird is a creature of incandescent beauty. The hue of his plumage transitions seamlessly from molten red to sunshine yellow. But that radiance is not enough to attract a mate. When males of most bowerbird species are ready to begin courting, they set about building the structure for which they are named: an assemblage of twigs shaped into a spire, corridor or hut. They decorate their bowers with scores of colorful objects, like flowers, berries, snail shells or, if they are near an urban area, bottle caps and plastic cutlery. Some bowerbirds even arrange the items in their collection from smallest to largest, forming a walkway that makes themselves and their trinkets all the more striking to a female—an optical illusion known as forced perspective that humans did not perfect until the 15th century.

Yet even this remarkable exhibition is not sufficient to satisfy a female flame bowerbird. Should a female show initial interest, the male must react immediately. Staring at the female, his pupils swelling and shrinking like a heartbeat, he begins a dance best described as psychotically sultry. He bobs, flutters, puffs his chest. He crouches low and rises slowly, brandishing one wing in front of his head like a magician’s cape. Suddenly his whole body convulses like a windup alarm clock. If the female approves, she will copulate with him for two or three seconds. They will never meet again.

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