gray, with a square patch on the loins, the tail and the fore arms being of a pure white; a gorget of chestnut surmounts the chest; the thighs are black, with the legs chestnut red. I will mention only two other monkeys for their beauty; and I have selected these as presenting slight sexual differ. ences in color, which renders it in some degree probable that

FIG. 78.-Cercopithecus diana (from Brehm).

both sexes owe their elegant appearance to sexual selection. In the mustache-monkey (Cercopithecus cephus) the general color of the fur is mottled greenish with the throat white; in the male the end of the tail is chestnut, but the face is the most ornamented part, the skin being chiefly bluish gray, shading into a blackish tint beneath the eyes, with

the upper lip of a delicate blue, clothed on the lower edge with a thin black mustache; the whiskers are orange colored, with the upper part black, forming a band which extends backward to the ears, the latter being clothed with whitish hairs. In the Zoological Society's Gardens I have often overheard visitors admiring the beauty of another monkey, deservedly called Cercopithecus diana (Fig. 78); the general color of the fur is gray; the chest and inner surface of the forelegs are white; a large triangular defined space on the hinder part of the back is rich chestnut; in the male the inner sides of the thighs and the abdomen are delicate fawn colored, and the top of the head is black; the face and ears are intensely black, contrasting finely with a white transverse crest over the eyebrows, and a long, white, peaked beard, of which the basal portion is black."

47

In these and many other monkeys, the beauty and singular arrangement of their colors, and still more the diversified and elegant arrangement of the crests and tufts of hair on their heads, force the conviction on my mind that these characters have been acquired through sexual selection exclusively as ornaments.

Summary. The law of battle for the possession of the female appears to prevail throughout the whole great class of mammals. Most naturalists will admit that the greater size, strength, courage, and pugnacity of the male, his special weapons of offence, as well as his special means of defence, have been acquired or modified through that form of selection which I have called sexual. This does not depend on any superiority in the general struggle for life, but on certain individuals of one sex, generally the male, being successful in conquering other males, and leaving a larger number of offspring to inherit their superiority than do the less successful males.

47 I have seen most of the above monkeys in the Zoological Society's Gardens. The description of the Semnopithecus nemæus is taken from Mr. W. C. Martin's "Nat. Hist. of Mammalia," 1841, p. 460; see, also, pp. 475, 523.

There is another and more peaceful kind of contest, in which the males endeavor to excite or allure the females by various charms. This is probably carried on in some cases by the powerful odors emitted by the males during the breeding season, the odoriferous glands having been acquired through sexual selection. Whether the same view can be extended to the voice is doubtful, for the vocal organs of the males must have been strengthened by use during maturity, under the powerful excitements of love, jealousy, or rage, and will consequently have been transmitted to the same sex. Various crests, tufts, and mantles of hair, which are either confined to the male or are more developed in this sex than in the female, seem in most cases to be merely ornamental, though they sometimes serve as a defence against rival males. There is even reason to suspect that the branching horns of stags, and the elegant horns of certain antelopes, though properly serving as weapons of offence or defence, have been partly modified for ornament.

When the male differs in color from the female, he generally exhibits darker and more strongly contrasted tints. We do not in this class meet with the splendid red, blue, yellow, and green tints, so common with male birds and many other animals. The naked parts, however, of certain Quadrumana must be excepted; for such parts, often oddly situated, are brilliantly colored in some species. The colors of the male in other cases may be due to simple variation, without the aid of selection. But when the colors are diversified and strongly pronounced, when they are not developed until near maturity, and when they are lost after emasculation, we can hardly avoid the conclusion that they have been acquired through sexual selection for the sake of ornament, and have been transmitted exclusively, or almost exclusively, to the same sex. When both sexes are colored in the same manner, and the colors are conspicuous or curiously arranged, without being of the least apparent use as a protection, and especially when they are associated with

various other ornamental appendages, we are led by analogy to the same conclusion, namely, that they have been acquired through sexual selection, although transmitted to both sexes. That conspicuous and diversified colors, whether confined to the males or common to both sexes, are as a general rule associated in the same groups and sub-groups with other secondary sexual characters serving for war or for ornament, will be found to hold good, if we look back to the various cases given in this and the last chapter.

The law of equal transmission of characters to both sexes, as far as color and other ornaments are concerned, has prevailed far more extensively with mammals than with birds; but weapons, such as horns and tusks, have often been transmitted either exclusively or much more perfectly to the males than to the females. This is surprising, for, as the males generally use their weapons for defence against enemies of all kinds, their weapons would have been of service to the females. As far as we can see, their absence in this sex can be accounted for only by the form of inheri tance which has prevailed. Finally, with quadrupeds the contest between the individuals of the same sex, whether peaceful or bloody, has, with the rarest exceptions, been confined to the males; so that the latter have been modified through sexual selection, far more commonly than the females, either for fighting with each other or for alluring the opposite sex.

PART THREE

SEXUAL SELECTION IN RELATION TO MAN

AND CONCLUSION

CHAPTER XIX

SECONDARY SEXUAL CHARACTERS OF MAN

Differences between man and woman-Causes of such differences and of certain characters common to both sexes-Law of battle-Differences in mental powers, and voice-On the influence of beauty in determin. ing the marriages of mankind-Attention paid by savages to ornaments -Their ideas of beauty in woman-The tendency to exaggerate each natural peculiarity

WT

ITH mankind the differences between the sexes are greater than in most of the Quadrumana, but not so great as in some, for instance, the mandrill. Man on an average is considerably taller, heavier, and stronger than woman, with squarer shoulders and more plainly pronounced muscles. Owing to the relation which exists between muscular development and the projection of the brows,' the superciliary ridge is generally more marked in man than in woman. His body, and especially his face, is more hairy, and his voice has a different and more pow erful tone. In certain races the women are said to differ slightly in tint from the men. For instance, Schweinfurth, in speaking of a negress belonging to the Monbuttoos, who inhabit the interior of Africa a few degrees north of the Equator, says, "Like all her race, she had a skin several shades lighter than her husband's, being something of the

1 Schaaffhausen, translation in "Anthropological Review," Oct. 1868, pp. 419, 420, 427.

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