On Growth and Form

D’Arcy Wentworth Thompson thought biologists had grown too quick to answer every question about an organism’s shape with the single word evolution. His 1917 book argues that physics and geometry do much of the work. A jellyfish takes the form of a drop of liquid falling through water, a bird’s bone is braced like an engineer’s truss, a shell grows along a logarithmic spiral, a sunflower head counts in Fibonacci numbers. The best known section shows how the skull of one fish becomes another’s when you stretch the grid it is drawn on. Biologists have argued with the book for a century, and nearly everyone who reads it comes away looking at living things a different way. Free PDF and EPUB editions are available here.