Even today the correct marriage is one with the daughter of the mother’s brother (real or classificatory). On the other hand, marriage with the daughter of the father’s sister, or the interchange of daughters, is forbidden. When Sternberg made his registration of families he discovered how greatly this custom preponderates even now.1

Buffalo-bird-woman laughed outright at the query whether Goodbird might marry Wolf-chief’s daughter, i.e., his maternal uncle’s daughter, whom he calls "daughter." The idea of a man marrying his daughter! It would be the same as though he were marrying his own child. She had never heard of such a case. People would regard such a married couple as dogs.2

In Arosi a boy must never speak to his cross-cousin: if he wants something from her he must get a friend to go and ask for it; he must never play with her; if they meet by chance on a path she will step aside into the bush to let him go by and they must not look at one another; he must never take food from her even if he is hungry, nor must he eat food she has cooked; if she is in a house he does not go in, but stands near the house, and when she observes him she goes out and then he can enter; he must not go on a voyage with her in a canoe or boat, and he must be very careful never to touch anything of hers—her bag, her lime-box, her sleeping mat, or to tread upon the last. The meaning of these restrictions is quite plainly seen when it is remembered what the mark of betrothal is in Arosi. If a boy feeds a girl and she eats the food this is consent to marry, and if afterwards the girl wishes to marry someone else, half a fathom of white shell money must be paid: in the case of young people it is only half a fathom, with older men and women a whole fathom; and exchange of bags is a public sign of agreement to marry.3

The fact that cross-cousin marriage is so prevalent and ortho-cousin marriage so frequently prohibited is probably due to the fact that under a classificatory system the children of a brother and sister always belong to different social groups, while the children of two brothers or two sisters will or may belong to the same social group. The cross-cousin marriage seems therefore to represent a conservative tendency in the development of exogamy, where the members of families are married out, but not in a distant way.

The above items seem to make it plain that the employment and development of exogamy, if not its origin, were closely associated with the extension of social relations. Nevertheless we may examine what grounds there may be for supposing that disinclination to marriage, say between brother and sister, is associated with daily contact in the family circle.

1Czaplicka, M.A.n/an/an/an/a, , 99 (Clarendon Press. By permission).

2 Lowie, "Notes on the Mandan, Hidatsa, and Crow Indians," 39.

3 Fox, op. cit., 117.