THE EVOLUTION OF ANTS
(species), some of which are very similar, though distinct—such as the various kinds of oaks, pines, deer, and ducks—and even the superficial observer knows that these species, though they may be very constant in many of their characteristics, are nevertheless more or less variable in others. And third, everybody knows that many of our breeds of domesticated animals and plants have given rise and are still giving rise under human control to other breeds, some of which show great differences from their ancestors, such as those, for example, seen among our dogs, pigeons, roses, and grapes. The facts of the first and the third group we can observe directly; those of the second group, showing classification, require explanation.
The resemblances and the differences between the kinds of animals and plants might be accounted for in two ways: either these several kinds were created independently, simultaneously or successively, or they were derived by natural descent from common ancestors, in the same manner as the various breeds of domestic animals and plants were derived from their ancestral forms. The first explanation is supernatural and nongenetic; the second is natural and genetic. There is no question as to which of these explanations the scientist and the philosopher must prefer, for, as Joseph McCabe says, “no plea for the supernatural origin of anything is valid so long as there is a possibility of a natural explanation of its origin.”
The changes noted in the three groups of facts discriminated above all come under the head of “development” in its general sense, but those of the first group comprise the development of individual organisms, whereas those of the second and third comprise the development of races. The term “development”, or “ontogeny,” is now commonly used of individual development; the terms “evolution,” or
[ 211 ]
