We have still to consider certain secondary sexual characters which, according to Mr. Darwin, must be regarded as ornaments. With these he classes the great horns which rise from the head, thorax, and clypeus of many male beetles; the appendages with which some male fishes and reptiles are provided; the combs, plumes, crests, and protuberances of many male birds; and various crests, tufts, and mantles of hair which are found in certain mammals. But some of these characters may be of use to the males in their fights for females, or serve as means of recognition. Mr. Wallace suggests that crests and other erectile feathers may have been useful in making the bird more formidable in appearance, and in thus frightening away enemies; while long tail or wing feathers might serve to distract the aim of a bird of prey.[1510] Moreover, characters of which we cannot yet perceive the use may in the future be brought under the law of utility, as has been the case in so many other instances. According to Mr. Wallace, the ornamental appendages of birds and other animals are due to a surplus of vital energy, leading to abnormal growths in those parts of the integument where muscular and nervous action are greatest.[1511] And where these “ornaments” are of no positive disadvantage to the species, certainly no other explanation is needed.
For other arguments which may be advanced against Mr. Darwin’s theory of sexual selection, reference may be made to Mr. Wallace’s criticisms in ‘Tropical Nature’ and ‘Darwinism.’ We have sufficient evidence that females are pleased or excited by the males’ display of their sexual colours,[1512] and are charmed by their songs. But Mr. Darwin’s theory presupposes, amongst many other things, that almost all the females of a species, over a wide area and for many successive generations, prefer exactly the same modification of the colour, or ornament or sounds.[1513] Moreover, if the secondary sexual characters are due to female choice, how shall we explain the strange fact that the taste of the females varies so much that there are scarcely two species in which the standard of perfection is exactly the same? This difficulty did not escape Mr. Darwin. “It is a curious fact,” he says, “that in the same class of animals sounds so different as the drumming of the snipe’s tail, the tapping of the woodpecker’s beak, the harsh trumpet-like cry of certain waterfowl, the cooing of the turtle-dove, and the song of the nightingale, should all be pleasing to the females of the several species.” And further, “What shall we say about the harsh screams of, for instance, some kinds of macaws; have these birds as bad taste for musical sounds as they apparently have for colour, judging by the inharmonious contrast of their bright yellow and blue plumage?”[1514]
The theory now suggested accounts fully for this difference in taste. The immense variability of the secondary sexual characters is precisely what might be expected, if their object is to make it easier for the sexes to find and recognize each other. And it is natural that the females should be pleased by colours, odours, or sounds which, by the association of ideas, are to them the symbols of the most exciting period of their lives. On the other hand, we know that differently coloured races of the same species may be disinclined to pair together.[1515] And here, I think, we may draw an important conclusion. The great stability of the secondary sexual characters which we find in wild species, but certainly not in animals under domestication, seems to be due chiefly to the fact that those males which most typically represent the peculiarities of their species have the best chance of finding mates.
The reader may have felt some surprise at this strange jump from the patria potestas to a discussion of merely zoological facts, which have nothing to do, directly, with the history of human marriage. But we have now to deal with the sexual selection of man, and, for the right understanding of this, it was necessary to show that the sexual selection of the lower animals is entirely subordinate to the great law of natural selection. Mr. Darwin discussed the origin of the secondary sexual characters as a preliminary to the statement of his theory regarding the origin of man, and of the different races of men. At the end of the next chapter we shall consider whether this theory appears to be in accordance with facts or not.
[CHAPTER XII]
THE SEXUAL SELECTION OF MAN: TYPICAL BEAUTY
By the “Sexual Selection of Man” is meant the choice made by men and women as regards relations with the opposite sex. Mr. Darwin has shown that such selection takes place among the lower Vertebrata, and, judging from what we know of domesticated animals, it is much more common in the case of females than in that of males. The male, indeed, as a rule, seems to be ready to pair with any female, provided she belongs to his own species.[1516] As this probably depends upon the great strength of his sexual impulse, we may infer that in primitive times, when man had a definite pairing season, he displayed a like tendency, and that the sexual instinct, in proportion as it has become less intense, has become more discriminating.
Even now woman is more particular in her choice than man, provided that the union takes place without reference to interest. A Maori proverb says, “Let a man be ever so good-looking, he will not be much sought after; but let a woman be ever so plain, men will still eagerly seek after her.”[1517] With regard to the Negroes of Sogno, Merolla da Sorrento states, “Women would have experience of their husbands before they married them, in like manner as the men were to have of them; and in this particular I can aver that they are commonly much more obstinate or fickle than men, for I have known many instances in which the men were willing to be married, while the women held back, and either fled away or made excuses.”[1518] Among the Eastern Central Africans, according to Mr. Macdonald, many cases are known of slave wives running away from free husbands, but none of slave husbands running away from free wives.[1519] In the crossings between unequal human races, the father almost always belongs to the superior race. “In every case,” says M. de Quatrefages, “and especially in transient amours, woman refuses to lower herself; man is less delicate.”[1520] Thus, cases in which negresses form unions with the indigenous men of America are very rare;[1521] and Dr. Nott, who wrote in the middle of this century, never personally met any one who was the offspring of a negro man and a white woman, because of the extreme rarity of such half-breeds.[1522] In New Zealand it sometimes happens that a European man marries a Maori woman; but Mr. Kerry Nicholls never came across an instance where a European woman had married a Maori man.[1523] Even in civilized society men are less particular in their connections than women of corresponding education, no doubt, would be, even if the rules of everyday morality were the same for both sexes.