Page:Carroll Lane Fenton - Darwin and the Theory of Evolution.djvu/41

 38 enthusiasts one would gain the idea that there were no traits in animals that were either useless or harmful, but that every structure and habit had been carefully selected with regard to their usefulness. For a while evolutionists and particularly amateur evolutionists, made a fad of sexual selection, and the more significant features of Darwin's work were slighted.

But the hypothesis contained a great weakness—it depended too much on the accuracy of the human mind as a gauge of the animal mind. It supposed that the thoughts of a man, looking upon the gorgeous plumage of a cock pheasant, were akin to those of the hen pheasant. It made possible the explanation of altogether too many things, and on a basis for which there was but the slightest psychological support. To hold that the minds of a beetle, a bird, an elephant, and a man were similarly affected by similar things was going too far, particularly when there was no way of proving the stand, or of testing it by experiment. Gradually sexual selection lost popularity, and in the reaction dragged with it the theory of natural selection. Indeed, though careful experiments in breeding have demonstrated too clearly for question the efficiency of selection, the part which selection, of whatever kind, played in evolution is far from settled. As Dr. A. F. Shull, one of the leaders among the younger zoologists of America, recently wrote, "There is no marked inclination among leading biologists to attribute to selection in nature, through the struggle for existence, anything but a minor and negative role in evolution."

In the years following 1874 Darwin wrote sev-