The absence of secondary sexual characters in man, such as the brightly coloured areas which are so conspicuous a feature of many of the lower apes, is to be explained by his fundamentally different mode of life. Such vivid hues obtain only in species which live in troops, and they serve as aphrodisiacs, ensuring mating to every female forming a part thereof, which would be by no means certain were there no external signs of her condition. Primitive man, like the higher apes, was instinctively monogamous, and of necessity solitary, till he had acquired a tolerable measure of self-control and neighbourliness. When lust possessed him, he was obliged, in making his maiden venture to scour the country in the search for the object of his desire. This found, and won, probably only after desperate conflict with the head of the family, the nuptial ceremonies would be short. The greater physical strength of the male and his higher brain capacity are probably the result of Natural, rather than of Sexual Selection. The former would weed out all the weakly and dull-witted in the ordinary course of the struggle for existence, the latter, during the early days of man’s development, would award the prizes of life to the most amorous and cunning, and to the most ambitious of the competitors. The secondary sexual characters of the female are chiefly negative characters, the absence of those which are conspicuous in the male. She retains more of the primitive characters of the race. This is the rule in regard to the animal kingdom. Wherever we desire to find the onward tendency of evolution, the latest developments of the race, we turn to the male; when we desire to learn something of the past history of the species we turn to the female and young. This standard, of course, yields by no means uniform results, for we find every gradation of progress on the part of the latter, till male and female and young are externally indistinguishable. But the order is almost invariably the same—first the male, then the female, then the young. Thus progress is more or less automatic or “Orthogenic,” as the scientific text books have it, new characters, as they appear, tending to go on increasing in amplitude till checked by Natural selection. It is to be noted, however, that this transference is limited, for the female never inherits characters which are concerned with aggressiveness to the same degree as in the males, as witness, for example, the brow-ridges and huge canines in the case of the gorilla.