Cats' Paws and Catapults: Mechanical Worlds of Nature and People

Nature and humans build their devices with the same earthly materials and use them in the same air and water, pulled by the same gravity. Why, then, do their designs diverge so sharply? Humans, for instance, love right angles, while nature's angles are rarely right and usually rounded. Our technology goes around on wheels--and on rotating pulleys, gears, shafts, and cams--yet in nature only the tiny propellers of bacteria spin as true wheels. Our hinges turn because hard parts slide around each other, whereas nature's hinges (a rabbit's ear, for example) more often swing by bending flexible materials.

In this marvelously surprising, witty book, Steven Vogel compares these two mechanical worlds, introduces the reader to his field of biomechanics, and explains how the nexus of physical law, size, and convenience of construction determine the designs of both people and nature.

Steven Vogel teaches at Duke University.

"Life is what biology's all about. Technology is something else altogether. Or so I believed before I got into a kind of biology that's about technology as well as life," begins biomechanics expert Steven Vogel in the preface to Cats' Paws and Catapults. Vogel examines the "mechanical worlds of nature and people" in such chapters as "The Stiff and the Soft" and "The Matter of Magnitude." Lots of line-drawing illustrations help readers understand the examples used to answer questions of animal and machine efficiency, design and repair. Vogel clearly loves the puzzles of biology--why, for instance, do daffodil stems bend at only one precise spot? This book is filled with intriguing answers to such hidden questions, and curious readers will eagerly dive into Vogel's investigations of whether nature or human design is superior and why the two technologies have diverged so much. --Therese Littleton