Origin of Species Variorum

Comparison with 1869

sexual differences to this agency: for we see peculiarities arising and becoming attached to the male sex in our domestic animals (as the greater development of the wattle in male carrier-pigeons, horn-like protuberances in certain fowls, &c.), which are in no way useful. We see analogous cases under nature,— for instance, the tuft of hair on the breast of the turkey-cock, which cannot be useful and can hardly be orna- mental;— indeed, had the tuft appeared under domestication, it would have been called a monstrosity. ↑

Illustrations of the Action of Natural Selection, or the Survival of the Fittest.

In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by cralt, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf was hardest pressed for food. I can under such circumstances see no reason to doubt that the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected,— provided always that they retained strength to master their prey at this or at some other period of the year, when they might be compelled to prey on other animals. I can see no more reason to doubt this, than that man can improve the fleetness of his greyhounds by careful and methodical selection, or by .. unconscious selection which results from each man trying to keep the best dogs without any thought of modifying the breed.

Text in this page (from paragraph 1300, sentence 500 to paragraph 1400, sentence 100, word 19) is not present in 1869

sexual differences to this agency: for we see peculiarities arising and becoming attached to the male sex in our domestic animals (as the wattle in male carriers, horn-like protuberances in the cocks of certain fowls, &c.), which we cannot believe to be either useful to the males in battle, or attractive to the females. We see analogous cases under nature, for instance, the tuft of hair on the breast of the turkey-cock, which can hardly be either useful or ornamental to this bird;— indeed, had the tuft appeared under domestication, it would have been called a monstrosity. ↑

Illustrations of the action of Natural Selection. —

In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by craft, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf is hardest pressed for food. .. Under such circumstances ... the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected,— provided always that they retained strength to master their prey at this or at some other period of the year, when they might be compelled to prey on other animals. I can see no more reason to doubt this, than that man can improve the fleetness of his greyhounds by careful and methodical selection, or by that unconscious selection which results from each man trying to keep the best dogs without any thought of modifying the breed.

Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might