It should scarcely be necessary to point out that this is a mistake.

On whichever side, indeed, we approach it, the implication that sex in man and animals is identical cannot be borne out.

From the point of view of those who accept this identity it would be much more correct to say that men are inferior, rather than on a level with animals, for in animals under natural conditions the sexual instinct is strictly subordinated to reproduction and very little susceptible to deviation, so that from the standpoint of those who wish to minimize sex, animals are nearer to the ideal, and such persons must say with Woods Hutchinson: "Take it altogether, our animal ancestors have quite as good reason to be ashamed of us as we of them." But if we look at the matter from a wider biological standpoint of development, our conclusion must be very different.
So far from being animal-like, the human impulses of sex are among the least animal-like acquisitions of man.

The human sphere of sex differs from the animal sphere of sex to a singularly great extent.[59] Breathing is an animal function and here we cannot compete with birds; locomotion is an animal function and here we cannot equal quadrupeds; we have made no notable advance in our circulatory, digestive, renal, or hepatic functions.

Even as regards vision and hearing, there are many animals that are more keen-sighted than man, and many that are capable of hearing sounds that to him are inaudible.