Sentiment of Kinship.—A higher degree of the sentiments of sympathy is developed when these do not remain limited to a temporary union, but when the union of the sexes is transformed into durable or even life-long marriage, as we see in monkeys and in most birds. In another manner the sentiments of sympathy are developed by extension of the family community to a greater number of individuals, who are grouped together for the common defense, as we see in swallows, crows, and to a higher degree, in the large organized communities of social animals, as the beavers, bees, ants, etc. In the latter, the sentiment of sympathy and duty nearly always affects all the individuals of the community, while anger and jealousy are extended toward every being which does not form part of it.
We must be blinded by prejudice not to comprehend that these same general facts, revealed by the study of biology and animal psychology, are repeated in the human mind. Some animals are even superior to the majority of men in the intensity of their sentiments of sympathy and duty, as well as in love and conjugal fidelity—monkeys and parrots, for example. In the social insects, such as the ants and bees, with their communities so solidly organized and so finely coördinated on the basis of instinct, the sentiment of social duty has almost entirely replaced the individual sentiments of sympathy. An ant or a bee only loves, so to speak, the whole assemblage of his companions. It does not sacrifice itself for any one of them in particular, but only for the community. In these animals the individual is only regarded as a number in the community whose motto is—one for all, but never all for one.
In bees especially, the degree of sympathy extended to a member or a class of the hive is exactly proportional to the utility of this member to the community. The working bees will kill themselves or die of hunger in order to nourish their queen, while in the autumn they ruthlessly massacre all the males or drones which have become useless.
Sentiments of Patriotism and Humanity.—The human brain, so powerful and so complicated, contains a little of all these things, with enormous individual variations. In man, the sentiments of sympathy and duty relate especially to the family, that is to say, they are to a great extent limited to individuals interested in a sexual community, viz., the conjoints and children, as occurs generally in mammals. It follows that sentiments of sympathy connected with larger communities such as remote relatives, the clan, the community, the country, those who speak the same language, etc., are relatively much weaker, and result from education and custom rather than from instinct. The weakest sentiment is certainly that of humanity, which regards each man as a brother and companion, and from which is evolved the general sentiment of solidarity or social duty. How can it be otherwise in a species which has lived for thousands or perhaps millions of years as small hostile tribes, separated from each other? Primitive men were so destitute of all humanitarian sentiment that they not only killed one another and practiced mutual slavery, but also martyred, tortured and even devoured one another.
In spite of all this, and as the result of custom and life in common, the individual sentiments of sympathy in man are easily extended to members of other races, especially as regards different sexes, so much so that enemies conquered and taken prisoners often became later on, owing to life in common, the friends or mates of their conquerors.
Antipathy.—Inversely, individual antipathies and enmity often occur not only between members of the same tribe but even between those of the same family. The latter may lead to parricide, fratricide, infanticide, or assassination of a conjoint.
Phylogeny of Love.—The social life of ants offers us some instructive analogies. In spite of the intense hostility of different colonies of ants among themselves, there may be obtained by habitude, often after many desperate combats, alliances between colonies which were hitherto enemies, even between colonies of different species. These alliances henceforth become permanent. This is very curious to observe at the time when the alliance begins to be formed. We then see certain individual hatreds persist, to a varying extent, for several days. Certain individuals of the weaker party are maltreated by other individuals of the conquering party. They cut off their limbs and antennæ and often martyrize them to death with a rabidness that sadly resembles human sentiments! Hatred and dispute between individuals of the same colony of ants are, on the other hand, extremely rare. I can guarantee the correctness of all these observations, having often repeated them myself and having recorded them in my works on the habits of ants. Moreover, they have since been confirmed by other writers.
After what we have just said, and especially if we take into consideration the numerous observations which have been made in biology, we can hardly doubt that the sentiment of sexual attraction, or the sexual appetite, has been the primary source of nearly all, if not all, the sentiments of sympathy and duty which have been developed in animals and especially in man. Many of these sentiments are no doubt little by little completely differentiated and rendered entirely independent of sexual sentiment, forming a series of corresponding conceptions adapted to divers social objects in the form of sentiments of amity. The latter in their turn have often become the generators of social formations and of a more generalized altruism. Many others, however, have remained more or less consciously associated with the sexual appetite, as is certainly the case in man.
This short sketch which we have given of the phylogenetic history of love and its derivatives is sufficient to show the immense influence which sexual life has exercised on the whole development of the human mind.
On the other hand, we must avoid exaggerating the actual importance of this influence. Young children, who possess neither sexual appetite nor corresponding sensations, already give evidence not only of intense sentiments of sympathy and antipathy, anger and jealousy, but also of commiseration, when they see those whom they love suffer; they may even show that they already possess the sentiment of duty or disinterested devotion. All these phylogenetic derivatives of the sentiments of sexual attraction are thus developed in the individual long before the sexual instinct itself, from which they have become absolutely independent. This does not prevent them being powerfully influenced by the sexual instinct when this awakes, or from being associated with its direct derivatives when the sexual appetite, properly so-called, is absent. Thus we see absolutely cold women become loving and devoted wives and mothers, and possessing a highly developed sense of kinship. Maternal love is a sentiment of sympathy derived from the sexual sentiment, adapted directly to children, who are the products of sexual life.