To the common eye, it appears that when they fly, birds just flap their wings down and push themselves up by creating flat pressure underneath. But, in fact, something radically different and absolutely fascinating happens — something Destin of Smarter Every Day explains with computational fluid dynamics:

Feathers, indeed, are among evolution’s greatest masterpieces of design. In the recently released Feathers: The Evolution of a Natural Miracle (public library), conservation biologist Thor Hanson marvels:

Animals with backbones, the vertebrates, come in four basic styles: smooth (amphibians), hairy (mammals), scaly (reptiles, fish), or feathered (birds). While the first three body coverings have their virtues, nothing competes with feathers for sheer diversity of form and function. They can be downy soft or stiff as battens, barbed, fringed, fused, flattened, or simple unadorned quills They range from bristles smaller than a pencil point to the thirty-five-foot breeding plumes of the Ongadori, an ornamental japanese fowl. Feathers can conceal or attract. They can be vibrantly colored without using pigment. They can store water or repel it. They can snap, whistle, hum, vibrate, boom, and whine. They’re a near-perfect airfoil and the lightest, most efficient insulation ever discovered. … Natural scientists from Aristotle to Ernst Mayr have marveled at the complexity of feather design and utility, analyzing everything from growth patterns to aerodynamics to the genes that code their proteins. Alfred Russel Wallace called feathers ‘the masterpiece of nature…the perfectest venture imaginable,’ and Charles Darwin devoted nearly four chapters to them in Descent of Man, his second great treatise on evolution.

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