While the female spider often kills and eats the male, monkeys, and parrots give proof of such a great mutual attachment that when one of the conjoints dies the other sinks into complete despair, ceases to eat, and perishes in its turn.
In this domain we find singular adaptations to special conditions of existence. Among the bees and ants, a third class of individuals, or neuters, formed by differentiation of females, do not copulate, and lay at the most a few eggs which are not fecundated and which occasionally develop by parthenogenesis.
Among the termites, another species of social ants, a similar state of things exists, but the neuters, or workers, are derived from the male sex as well as the female and their sexual organs are quite rudimentary. The third sex, or worker, not only has a cerebral development superior to the sexual individuals, but also inherits the social sympathetic irradiations of the sexual appetite, which results in his devotion to a brood which is not his own. Among the social insects the males are little more than flying sexual organs, which after copulation are incapable of leading an independent existence and die of hunger and exhaustion in the case of ants or termites, or are massacred by the workers in the case of bees.
The fecundated females, on their part, become breeding machines whose activity is incessant. Among the ants, however, the females are at first capable of nourishing a few larvæ by the aid of a portion of their eggs and their secretions, till the workers are hatched, who henceforth undertake all the work including the maternal care of the brood.
Whoever has observed the fidelity of a pair of swallows and the way in which the male and female nourish and rear their young, must be struck by the analogy to the conjugal and family love of the faithful type of human beings. This is especially remarkable when the same couple return every year to the old nest. This family life of the swallows does not prevent a certain social life, which manifests itself in organized attacks on birds of prey, and in combined emigration in the autumn and spring.
On the other hand, we are instinctively indignant at the want of fidelity in other animals, between conjoints, parents and offspring (dogs and rabbits, for instance), because we involuntarily expect to find in them our own moral sense, which is not at all just.
From the phylogenetic point of view we can only compare ourselves to the higher apes, by their analogies with primitive man. (Vide Chapter VI.) The question which concerns us here is as follows: If we consider the peculiarities of our sexual customs with those of our direct ancestors, what are those which are derived from ancient and profound phylogenetic instincts, those which are derived from less profound ancestral energies (i.e., relatively more recent) and lastly those which depend simply on old customs fixed by tradition, prejudice and habit? If we are careful we shall immediately recognize that it is not only the sexual appetite itself, but also a large part of its correlatives and irradiations, in which the phylogenetic roots are deep. Jealousy, coquetry, instinctive maternal love, fidelity and conjugal love, which are more or less developed in primitive man, are also present in monkeys and birds. We have even seen that the conjugal fidelity of these often exceeds our own. It is, therefore, not true that our animal ancestors are only allied to us by sexual appetite; on the contrary, we must admit that they have much more noble sentiments and instincts, derived it is true from this appetite, but belonging to the domain of a higher social morality. All that we can say in a general way concerning the complex entanglement of our sentiments and instincts is that, the most deeply rooted characters in human nature are at the same time, phylogenetically speaking, the most ancient.
Among the most profound instincts of sexual life, we find moral and intellectual incongruities. Along with excitement of the sexual appetite in the male by the odor of the female genital organs, or by the sight of erotic pictures, we find the most touching conjugal love, and life-long devotion of one conjoint for the other and for the children. Prostitution, marriage by purchase, religious marriage, disgrace attached to illegitimate births, conjugal and family rights of one or the other sex, etc., are, on the contrary, things which do not depend on recent phylogeny, but only on the customs and traditions of certain races. They are partly outgrowths from egoism, the spirit of domination, mysticism and hypocrisy, and partly the shifts of an overheated social life which is becoming more and more complicated.
Westermark's studies are very instructive in this respect. All the absurdities and contradictions, brought to light by the historical and ethnographical study of the customs and matrimonial abuses in man, allow us to clearly distinguish that which is due to fashion or custom, from that which is deeply rooted in our heredity. To avoid repetition I refer my readers to Chapter VI, to examine the differences between heredity and custom.
Between these two extremes there is, however, one important domain, viz., that of recent phylogeny, or in other words variation. The fixed appetites and instincts of the species which are proper to every normal man, and are as we have seen fundamentally connected with many animal forms, belong to ancient and profound phylogeny. But there is another group of very variable peculiarities, strongly developed in some men and little in others, sometimes completely absent, which do not depend on custom but on what is called individual hereditary disposition, or individual character. While some men have monogamous instincts others are polygamous. Some men are by instinct and heredity very egoistic, others more altruistic. This peculiarity is reflected in their sexual life and changes the character of their love (but not that of their sexual instinct). The egoist may love his wife, but this love is interested and very different from that of the altruist. Between the two extremes there is an infinite number of gradations according to the nature of the instincts and dispositions. The same man may be a good and generous father, and a social exploiter with neither shame nor pity. Another will pose as a social benefactor, while at home he is an egoist and a tyrant. The individual dispositions of recent phylogeny are combined in every way with education, customs, habit and social position to produce results which are often paradoxical, and the factors of which are ambition, vanity, temper, etc. Recent phylogeny is reflected also in many of the irradiations of the sexual appetite of which we have spoken in Chapter V. Audacity, jealousy, sexual braggardism, hypocrisy, prudery, pornography, coquetry, exaltation, etc., depend in each particular case, according to their degree of development, on a combination of individual sexual hereditary dispositions with individual dispositions in the other domains of sentiment, intelligence and will. In this way, the sexual individuality of one man is constituted in a very complex and very different way to that of other men, owing to the high development of the human brain, as well as to the infinite variability and adaptability of his aptitudes. It is impossible to give even an incomplete explanation of all the symphonic gradations (often cacophonic) which represent an individuality, or to fix clearly what distinguishes it from others. However, when the principle is understood, it is not difficult to estimate the sexual individuality of each person more or less correctly.