We have seen that the prohibitions against incest are very often more or less one-sided, applying more extensively either to the relations on the father’s side or to those on the mother’s, according as descent is reckoned through men or women. We have also seen that the line of descent is intimately connected with local relationships; and we may now fairly infer that the same local relationships exercise a considerable influence on the table of prohibited degrees. Among the Rejangs of Sumatra, says Marsden, a marriage must not take place between relations within the third degree; “but there are exceptions for the descendants of females who, passing into other families, become as strangers.”[1958] A Chinese woman, on marriage, alienates herself from her own family to be incorporated into that of her husband; hence, as Mr. Medhurst observes, children of brothers and sisters may marry at pleasure, while those of brothers cannot be united on pain of death.[1959]
In a large number of cases, prohibitions of intermarriage are only indirectly influenced by the close living together. Aversion to the intermarriage of persons who live in intimate connection with each other has provoked prohibitions of the intermarriage of relations; and, as kinship is traced by means of a system of names, the name comes to be considered identical with relationship. This system, as Dr. Tylor remarks,[1960] is necessarily one-sided. Though it will keep up the record of descent either on the male or female side, it cannot do both at once. The other line, not having been kept up by such means of record, even where it is recognized as a line of relationship, is more or less neglected, and is soon forgotten; hence the prohibited degrees often extend very far on the one side, but not on the other. We have seen many instances of a common surname being a bar to intermarriage. This is especially the case with peoples among whom the clannish feeling is highly developed. Thus even the commonest Chinese are often able to trace their descent through lines of ancestry more remote than any that England’s most ancient families can claim.[1961] And, among the Ossetes, a man is bound to take blood-revenge for a cousin a hundred times removed who bears his name, whereas relationship on the mother’s side is not recognized.[1962]
Generally speaking, the feeling that two persons are intimately connected in some way or other may, through an association of ideas, give rise to the notion that marriage or intercourse between them is incestuous. Hence the prohibitions of marriage between relations by alliance and by adoption. Hence, too, the prohibitions on the ground of what is called “spiritual relationship.” The Emperor Justinian passed a law forbidding any man to marry a woman for whom he had stood as godfather in baptism, the tie of the godfather and godchild being so analogous to that of the father and child as to make such a marriage appear improper.[1963] In the Roman Church sponsorship creates a bar to the marriage even of co-sponsors, and the restriction can be removed only by a dispensation.[1964] In Eastern Europe, the groomsman at a wedding comes under a set of rules which forbids intermarriage with the family of the bride to exactly the same extent as if he were naturally the brother of the bridegroom.[1965] A similar cognatio spiritualis, according to the old law-books of India, occurs between a pupil and his “guru,” that is, the teacher who instructs him in the Veda. The pupil lived in his guru’s house for several years, and regarded him almost as a father.[1966] Hence adultery with a guru’s wife was considered a mortal sin.[1967]
But how, then, are we to explain the exceptions, apparent or real, to the rule that close living together inspires an aversion to intermarriage? How are we to explain the fact that, besides tribes that are exogamous, there are others that are endogamous, and that, besides peoples with very extensive laws against intermarriage, there are others among whom unions take place between very near relations, such as brothers and sisters, and even parents and children.
In the next chapter we shall examine the psychological principle which underlies the endogamous marriage. For the present it is sufficient to say that endogamy never, except in cases of extreme isolation, seems to occur among peoples living in very small communities with close connections between their members. Concerning the Australians, Mr. Curr expressly states that those tribes which are endogamous are, as a rule, stronger in numbers than those in which exogamous marriage obtains.[1968]
The marriage of brother and sister means, as we have seen, in most cases, marriage between a half-brother and a half-sister, having the same father but different mothers. Such marriages are not necessarily contrary to the principle here laid down. Polygyny breaks up the one family into as many sub-families as there are wives who have children, and it is not possible for the father of these sub-families to be a member of each of them in the same sense as the father is a member of the monogamous family. Nor are the children of the different mothers brought into such close contact as the children of one mother, every wife with her own family forming a little separate group, and generally living in a separate hut.[1969] On the contrary, hatred and rivalry are of no rare occurrence among the members of the various sub-families. In the Pelew Islands, according to Herr Kubary, it very seldom happens that the several wives of the same man even see each other.[1970] After speaking of the marriage of half-brother and half-sister allowed among the ancient Arabs, Professor Robertson Smith remarks, “Whatever is the origin of bars to marriage, they certainly are early associated with the feeling that it is indecent for housemates to intermarry.”[1971]
Most of the recorded instances of intermarriage of brother and sister refer to royal families, to the exclusion of others; and there is no difficulty in accounting for incestuous unions of this sort. Among lower races, as well as in Europe, it is considered improper for royal persons to contract marriage with persons of less exalted birth. But whilst European princes may go to some friendly Court for their consorts, a similar course is not open to African or Asiatic potentates.
Incestuous unions may also take place on account of necessity, as among the Wa-taïta, or on account of extreme isolation, as among the Karens of the Tenasserim Provinces,[1972] several of the small tribes of Brazil, and especially the Veddahs of Ceylon. Among the wild Veddahs, the different families are separated from each other by great distances, and it is only accidentally or occasionally that any others besides the members of one family are brought together.[1973] The reason for the practice of marrying a sister, says Professor Virchow, “was probably the same everywhere, in the royal families as with the naked Veddahs, the lack of suitable women or of women altogether.”[1974]
Certain instances of incestuous connection are evidently the results of vitiated instincts, the origin of which we are not able to trace. It is a remarkable fact that several of the peoples among whom incestuous intercourse is said to be practised are, at the same time, expressly stated to indulge in bestiality or other unnatural vices.[1975] This shows that their sexual feelings are altogether in a perverted state.
Much stress has been laid by anthropologists on the few instances of peoples who habitually or occasionally contract unions which we should consider criminal. They have been taken for surviving types of the primitive condition of man, proving that “sentiments such as those which among ourselves restrain the sexual instincts are not innate.”[1976] But it is obvious that they prove nothing of the kind. Students of early history have often paid too much regard to exceptions, and too little to rules, overlooking the fact that there is no rule which has no exceptions.