12. This theory, which bases exogamy on the unconscious result of natural selection, gradually weeding out those groups which persisted in the practice of endogamy, and replacing them by a healthier and more vigorous race, seems on the whole best to account for existing facts. It is, however, perhaps premature to suppose that in all cases the same end was reached by the same course. All through the myths of early India nothing comes out more clearly than the instructive hatred of the Arya or white man for the Dasyu, or the man of the black skin. The balance of opinion now seems to be moving in the direction of assuming that the so-called Aryan invasion was much more moral than physical, that the attempt to discriminate between the ethnological strata in the population is practically impossible. The conversion may have been the work, not of armies of invaders moving down the valleys of the Ganges and Jumna, but of small bodies of missionaries who gradually effected a moral conquest and introduced their religion and law among a population with whom they ultimately to a large extent amalgamated. That some form of exogamy was an independent discovery made by the autochthones prior to their intercourse with the Aryans seems certain; but it is possible that the special form of prohibited degrees which was enforced among the higher races may have been to some extent the result partly of their isolation in small communities among a black-skinned population, and partly, as Dr. Tylor suggests, as a means of enhancing the political importance and establishing the influence of these groups. That this procuring of suitable brides from foreign groups was sometimes impossible is proved by the curious Buddhistic legend that the Sakyas became endogamous because they could get no wives of their own rank, and were in consequence known as “pigs” and “dogs” by their neighbours. [49] [Exogamy and Totemism.] 13. There is, however, another side to the discussion on the origin of exogamy which must not be neglected. In another place I have collected some of the evidence as to the existence of totemism in Northern India. [50] The present survey has given indication of the existence of totemistic sections among at least twenty-four tribes, most of whom are of Dravidian origin. Now we know that one of the ordinary incidents of totemism is that persons of the same totem may not marry or have sexual intercourse with each other, [51] and it is perhaps possible that, among the Dravidians at least, one basis of exogamy may have rested on their totemistic group organization. The indications of totemism are, however, too vague and uncertain, being mainly based on the fact that the names of many of their sections are taken from those of animals and plants, to make it possible at present to express a definite opinion on such an obscure subject. CHAPTER VI. FORMS OF HINDU MARRIAGE.