Let us first examine the balance of forces by which these two great processes, self-preservation and race-preservation, are conducted in the world. Self-preservation involves the expenditure of energy in those acts, and their ensuing modifications of structure and function, which tend to the maintenance of the individual life. Race-preservation involves the expenditure of energy in those acts, and their ensuing modifications of structure and function, which tend to the maintenance of the racial life, even to the complete sacrifice of the individual. This primal distinction should be clearly held in mind. Self-preservation and race-preservation are in no way identical processes, and are often directly opposed. In the line of self-preservation, natural selection, acting on the individual, develops those characteristics which enable it to succeed in “the struggle for existence,” increasing by use those organs and functions by which it directly profits. In the line of race-preservation, sexual selection, acting on the individual, develops those characteristics which enable it to succeed in what Drummond has called “the struggle for the existence of others,” increasing by use those organs and functions by which its young are to profit, directly or indirectly. The individual has been not only modified to its environment, under natural selection, but modified to its mate, under sexual selection, each sex developing the qualities desired by the other by the simple process of choice, those best sexed being first chosen, and transmitting their sex-development as well as their racial development.
The order mammalia is the resultant of a primary sex-distinction developed by natural selection; but the gorgeous plumage of the peacock’s tail is a secondary sex-distinction developed by sexual selection. If the peacock’s tail were to increase in size and splendor till it shone like the sun and covered an acre—if it tended so to increase, we will say—such excessive sex-distinction would be so inimical to the personal prosperity of that peacock that he would die, and his tail-tendency would perish with him. If the peahen, conversely, whose sex-distinction attracts in the opposite direction, not by being large and splendid, but small and dull—if she should grow so small and dull as to fail to keep herself and her young fed and defended, then she would die; and there would be another check to excessive sex-distinction. In herds of deer and cattle the male is larger and stronger, the female smaller and weaker; but, unless the latter is large and strong enough to keep up with the male in the search for food or the flight from foes, one is taken and the other left, and there is no more of that kind of animal. Differ as they may in sex, they must remain alike in species, equal in race-development, else destruction overtakes them. The force of natural selection, demanding and producing identical race-qualities, acts as a check on sexual selection, with its production of different sex-qualities. As sexes, they perform different functions, and therefore tend to develop differently. As species, they perform the same functions, and therefore tend to develop equally.
And as sex-functions are only used occasionally, and race-functions are used all the time—as they mate but yearly or tri-monthly, but eat daily and hourly—the processes of obtaining food or of opposing constant enemies act more steadily than the processes of reproduction, and produce greater effect.
We find the order mammalia accordingly producing and suckling its young in the same manner through a wide variety of species which obtain their living in a different manner. The calf and colt and cub and kitten are produced by the same process; but the cow and horse, the bear and cat, are produced by different processes. And, though cow and bull, mare and stallion, differ as to sex, they are alike in species; and the likeness in species is greater than the difference in sex. Cow, mare, and cat are all females of the order mammalia, and so far alike; but how much more different they are than similar!
Natural selection develops race. Sexual selection develops sex. Sex-development is one throughout its varied forms, tending only to reproduce what is. But race-development rises ever in higher and higher manifestation of energy. As sexes, we share our distinction with the animal kingdom almost to the beginning of life, and with the vegetable world as well. As races, we differ in ascending degree; and the human race stands highest in the scale of life so far.
When, then, it can be shown that sex-distinction in the human race is so excessive as not only to affect injuriously its own purposes, but to check and pervert the progress of the race, it becomes a matter for most serious consideration. Nothing could be more inevitable, however, under our sexuo-economic relation. By the economic dependence of the human female upon the male, the balance of forces is altered. Natural selection no longer checks the action of sexual selection, but cooperates with it. Where both sexes obtain their food through the same exertions, from the same sources, under the same conditions, both sexes are acted upon alike, and developed alike by their environment. Where the two sexes obtain their food under different conditions, and where that difference consists in one of them being fed by the other, then the feeding sex becomes the environment of the fed. Man, in supporting woman, has become her economic environment. Under natural selection, every creature is modified to its environment, developing perforce the qualities needed to obtain its livelihood under that environment. Man, as the feeder of woman, becomes the strongest modifying force in her economic condition. Under sexual selection the human creature is of course modified to its mate, as with all creatures. When the mate becomes also the master, when economic necessity is added to sex-attraction, we have the two great evolutionary forces acting together to the same end; namely, to develop sex-distinction in the human female. For, in her position of economic dependence in the sex-relation, sex-distinction is with her not only a means of attracting a mate,
