Strong hereditary dispositions of character may be recognized in early infancy. When the ancestry of a man is well known the roots of his recent phylogeny may be traced to his ancestors. Here we observe the effect of crossing between varieties or different races, or on the contrary that of consanguinity. This effect is observed in character and in sexual disposition, as much as in the shape of the nose, or the color of the skin and hair, etc. It is important that men should learn to know themselves, and also study each other from this point of view before marrying. On the whole, we may say that the average civilized man of our race possesses as his "phylogenetic baggage" a strong sexual appetite, very variable sentiments of love, generally somewhat mediocre, (we have seen that conjugal love is more strongly developed in most monkeys than in man), lastly altruistic or social sentiments which are still deplorably weak. The latter, no doubt, form no part of the sexual life, but they must be taken into consideration for they are its most important derivatives, and it is indispensable for our modern social life to develop them in harmony with family and conjugal love.
Hereditary instincts can easily be observed in children. When one of them is good, it gives evidence at an early age of the sentiments of sympathy or altruism, such as pity and affection, as well as an instinctive sentiment of duty, the object of which is not yet social. All these sentiments are at first only applied to human individuals known to the child, domestic animals, or even inanimate objects. On the other hand, the ant, from the beginning of its existence, shows an inherited instinct or sentiment of complete social duty. In man, social sentiments properly so-called, have to be acquired by education, but they require for their expansion a considerable degree of inherited sentiments of sympathy and duty. A person without morals can easily acquire social phraseology but not social sentiment. A few more points require to be considered.
Monogamy is no doubt an old and well-established phylogenetic heritage, while polygamy is on the whole rather an aberration produced by individual power and wealth. But phylogenetic monogamy is by no means identical with the religious or other formality of our present legal monogamy. It assumes first of all an early marriage immediately after puberty, while our civilization has placed between this and marriage, which it only allows later as a rule, the unhealthy swamp of prostitution, which so often sows in the individual the destructive seed for his future legal union, before this has taken place. Again, phylogenetic monogamy imposes no legal constraint; on the contrary, it assumes a free, natural and instinctive inclination in each of the conjoints, when it is not the result of the brute force of the male. Lastly, it by no means excludes a change after a certain time. We are speaking only of man, and not of birds and monkeys, who are more monogamous than ourselves.
Monogamy without children has little reason for its existence and must be considered simply as a means to satisfy the sexual appetite or as a union for convenience. It is the same with certain marriages between individuals of very different ages, especially the marriage of a young man with a woman already old and sterile.
As far as we can ascertain, the majority of sexual perversions, of which we shall speak in Chapter VIII, are a sad pathological acquisition of the human race. We observe, however, especially in the higher mammals, acts of pederasty between males when the female is wanting.
The sexual repulsion which normally exists between animals of different species rests on a selective basis, the hereditary mneme of their reciprocal germs being unable to place itself in homophony, and their blood also having a mutual toxic action. In speaking of sodomy we shall see that this instinctive repulsion may disappear in pathological cases, both in man and in animals, owing to bad habits or unsatisfied sexual appetite. We cannot absolutely demonstrate the phylogenetic existence of an instinctive disgust for consanguineous sexual intercourse.
The sexual advances made by women in civilized countries, show how easily we may be deceived in attributing to a phylogenetic or hereditary origin, certain details which are only due to external circumstances. In man, the bearer of the active germ, the instinct of sexual advance has deep phylogenetic roots. It is quite natural to him and is evident among savage races, where the man risks more by remaining single than the woman. Violent combats between rivals to obtain the woman, who remains passive like most animals, are evidence of this.
Civilization has changed all this, and has developed two castes of women, the old maids and the prostitutes. The latter satisfy the appetites of men in an artificial and unhealthy manner, while marriage and family cares only bring them labor and burdens instead of riches. Owing to the promiscuous polyandry of prostitution, man can always obtain enough women, while woman can with difficulty obtain a suitable husband. These circumstances have more and more developed the art of flirtation, coquetry and advances on the part of girls, and we can now see, especially in the United States, that advances come more and more from the female side, if not in principle, at any rate in fact. This is not a question of a phylogenetic or hereditary transformation of the sexes among civilized peoples, but an unhealthy effect resulting from abnormal circumstances, that is the non-satisfaction of the sexual desires of woman, together with the satiety of those of men. Woman makes advances from the fear of remaining celibate; she will cease to do so when the unnatural causes which have produced this state of things have been done away with.
As a rule, a normal and adaptable man will conduct himself in sexual matters as in others according to the prevailing fashion. He will most often succeed in accommodating his sentiments to those of his conjoint. On the other hand, this average representative of normal mediocrity easily becomes the slave of routine and incapable of new ideas. However normal he may be, he has less faculty of adaptation or mental plasticity and less liberty, than a man of higher nature independent of prejudices.