But such cases are rare. Besides, most of them imply only that the children in a certain way belong to the uncle, not that the father is released from the obligation of supporting them. Even where succession runs through females only, the father is nearly always certainly the head of the family. Thus, for instance, in Melanesia, where the clan of the children is determined by that of the mother, “the mother is,” to quote Dr. Codrington, “in no way the head of the family. The house of the family is the father’s, the garden is his, the rule and government are his.”[202] Nor is there any reason to believe that it was generally otherwise in former times. A man could not of course be the guardian of his sister’s children, if he did not live in close connection with them. But except in such a decidedly anomalous case as that of the Malays, just referred to, this could scarcely happen unless marriages were contracted between persons living closely together. Nowadays, however, such marriages are usually avoided, and I shall endeavour later on to show that they were probably also avoided by our remote ancestors. It might, further, be objected that the children were equally well or better provided for, if not the fathers only, but all the males of the tribe indiscriminately were their guardians. The supporters of the hypothesis of promiscuity, and even other sociologists, as for instance Herr Kautsky,[203] believe that this really was the case among primitive men. According to them, the tribe or horde is the primary social unit of the human race, and the family only a secondary unit, developed in later times. Indeed, this assumption has been treated by many writers, not as a more or less probable hypothesis, but as a demonstrated truth. Yet the idea that a man’s children belong to the tribe, has no foundation in fact. Everywhere we find the tribes or clans composed of several families, the members of each family being more closely connected with one another than with the rest of the tribe. The family, consisting of parents, children, and often also their next descendants, is a universal institution among existing peoples.[204] And it seems extremely probable that, among our earliest human ancestors, the family formed, if not the society itself, at least the nucleus of it. As this is a question of great importance, I must deal with it at some length. Mr. Darwin remarks, “Judging from the analogy of the majority of the Quadrumana, it is probable that the early ape-like progenitors of man were likewise social.”[205] But it may be doubted whether Mr. Darwin would have drawn this inference, had he taken into consideration the remarkable fact that none of the monkeys most nearly allied to man can be called social animals.