In an article on whale evolution (Natural History 5/94) peppered with negative remarks toward creationists, S. J. Gould (d. 2002) of Harvard, perhaps one of the more strident anti-creationists, stated:

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.

There is much misinformation about these two words, and yet, understanding them is perhaps the crucial prerequisite for understanding the creation/evolution issue.

As one might imagine, different answers to this question come from different "authorities." Obviously, creationists and evolutionists disagree, but major schools of thought vie among evolutionists.

Darwin's book Origin of Species, published in 1859, proposed the concept of evolution by purely naturalistic causes, especially natural selection. His idea was that the small variations observed within a population of plants or animals would lead to large changes, given a fortuitous environmental change which favored the variant's opportunity for survival and reproduction.