Four-legged animals have at least as many back problems as humans. Think of the race horse with back-related lameness, or the Dachshund with a slipped disk. Any veterinarian will tell of the multitude of pets and livestock who had to be "put down" because of back problems. In the wild, animals fare no better.

Years ago, students were taught that the definition of science is "the search for truth." But things seldom stay the same. In recent years, some scientists have tried to equate science with naturalism—"the search for a naturalistic explanation for all things."