Facing the World

An essay in twenty chapters on the branch of the tree of life we inhabit: the bilateral animals. Why does an animal have a front? Why are most built around a single axis, with a mouth at one end and a gut running through to the other? Why do senses and brain gather at the leading end? Tracing the story from the Burgess Shale back through the Cambrian and forward through a cascade of inventions — through-gut, head, coelom, segmentation, skeletons, walking, the warm body — the book argues that bilaterality is the widest answer ever found to a single problem: how to extract energy from the world.

Contents