Page:Popular Science Monthly Volume 67.djvu/71

Rh nothing to do with the origin of species, but with the survival of already formed species. Not selection of the fittest individuals, but the survival of the sufficiently fit species.

There is a fundamental difference between the idea that fluctuating variations become specific characters through accumulation by selection, and the idea that new species arise as definite variations, which, with their appearance, characterize the new form as a new species. According to the Darwinian theory, natural selection performs a double duty, first, to build up new species, and, second, to maintain them in competition with other species. According to the other view, species are not formed by any kind of selection, and the question of survival only concerns the maintenance of species, already formed. The primary problem is the problem of the 'origin of species.' The central idea is not what species survive, but how species originate; no matter whether they are going to become victorious or not.

After a species has appeared it will surely be admitted by every one, that forms that can survive will survive! If Darwin's theory meant only this to those who adopted it, is it not surprising that such a truism should have been hailed as a great discovery? Was not the theory heralded because it seemed to explain how new species arose? What shall we say then when we find a situation like that existing at the present time, when we are told that after all the only difference between Darwin's theory of natural selection and the theory of the survival of definite variations is that in the one case fluctuating variations are selected, and in the other mutations, and that in both cases natural selection is the key to the evolutionary process! Is not the 'origin of species' still the real point at issue?

I yield to no one in admiration for what Darwin has done in behalf of the biological sciences, for he succeeded, where the great French zoologists failed, in establishing the principle of evolution. Furthermore no other hypothesis, that has as yet been proposed, accounts so well for the widespread occurrence of adaptation of organisms to the environment as does the principle of natural selection. But appreciation of Darwin's claims in these directions need not blind us to the insufficiency of the theory of natural selection to account for the origin of species; nor to the fact that his followers have been especially concerned in propounding and making application of this side of the theory. They have shown little interest in selection as the great conserving factor of evolution, and the reason for this is not far to seek, because of the much greater importance that they have attributed to natural selection as a creative factor in building up individual differences into specific characters.