Discover, July 31, 1998
If you find yourself in prairie dog country, you may notice that one opening to their burrows is always built up a few inches aboveground. There’s a very good reason for this: thanks to the quirks of fluid dynamics, the higher aboveground you are, the faster the wind blows. This means that the air moving over the raised opening is at higher pressure than that moving over the other entrance, and since high pressure always flows to low, a cool breeze is pushed through the burrow. The prairie dogs get fresh air without using a single watt to power a fan or an air conditioner.
The natural reaction to such natural engineering is amazement. It springs from the same sense of wonder that led many biologists before Darwin to claim that the ingenious designs found everywhere in the living world could only be the direct result of a divine designer. Although biologists now recognize that things like prairie dog burrow architecture are the result of natural selection, the unquestioning admiration of natural design still has a tight hold over people, according to Steven Vogel, a biologist at Duke University. Any human technology, the thinking goes, pales in comparison with some far superior version in nature. Yet, as Vogel points out, you can get yourself into trouble with this belief. It may be true that spider silk is quite strong, but you wouldn’t want to make parachute cords with it. Because of its structure, when the silk stretches, it heats up. This isn’t a problem for a dangling spider, since a strand of silk is so thin the heat quickly dissipates. But a thick cord on a parachute might well snap.
Vogel is the author of several previous books on biomechanics, such as the excellent Vital Circuits and Life’s Devices, and can be counted on to bring clarity and pleasure to esoteric aspects of physics. In Cats’ Paws he once again fits in a dense collection of elegant case studies, ranging from the bending of daffodils to beetles that walk on water. His longtime followers may be familiar with some of these examples, but here he puts them to new use. He argues that nature can be an inspiration for invention only if the problem at hand is very close to the one biology has actually solved. Otherwise, we will be doomed to failure. “Nature may show what’s possible,” Vogel explains, “but she’s a poor guide to what’s worth doing.”
Copyright 1998 Discover Magazine. Reprinted with permission.