EXCHANGE MARRIAGE. As workers and potential wives and mothers, all women are valuable to the community of which they are members. For this reason, amongst many primi tive peoples a man can only get a mate by compensating the group from which he takes her. This compensation can be in the form of goods or service or of another woman. Though sometimes a woman has much frecdom in choosing a husband, where marriageable women are scarce (owing to polygyny or, to restrictive marriage prohibitions) she is more or less at the disposal of her guardian, generally her father or maternal uncle or brother, who may use her as a means of procuring a wife for himself by exchanging her for another man's sister or daughter. In Australia and New Guinea and parts of the Pacific this is the most widely recognized way of arranging marriages. Commonly two men will marry each other's sisters (almost always real, not "classificatory"). If a man has several sisters, he has generally the right to dispose of all of them and so can obtain an equal number of wives; but if there are several of each sex in a family every brother in age order has a right to one sister, though, in Australia, a man will sometimes deprive his sons by exchanging a daughter for a wife for himself. In the island of Erromanga (West Pacific), where there is local exogamy (see EXOGAMY), the transaction concerns districts not families. If a man of district A wishes to marry a girl of district B, a girl of his own district, not necessarily his own sister, must be set aside for a return match, and both girls must be approved by the district chiefs.
In other parts of the world marriage by exchange is substituted for "marriage by purchase." If a man is too poor to collect the necessary "bride-price" for a wife, he may seek out another similarly circumstanced and effect an exchange of sisters. This is done to-day in many parts of India, by the Fellahin of Pales tine and by less cultured peoples. Even where "marriage by pur chase" is general we may see another form of exchange in the custom, found in East Africa and elsewhere, of regarding the wealth obtained by the marriage of a woman as belonging by right to her brother, wherewith he may obtain a bride.
Among some tribes who normally practise exchange marriage, part of the ceremony consists in what appears to be the paying of a bride-price, which would be superfluous, if the exchange of women were for economic reasons. It is often the case with so called "marriage by purchase," however, that the woman is not "bought" from her people, but that the exchange of gifts which takes place is of purely sociological not economic significance and has as its object the ceremonial uniting of the groups of bride and bridegroom. In Erromanga, when, after a marriage between two districts, a return marriage is made, part of the "bride-price" paid consists of the very goods which changed hands during the first marriage. Thus in some places the ex change of women may have originated for a similar reason.
In Australia, and among many tribes in India, exchange mar riage is definitely associated with the marriage of cross-cousins (see COUSIN MARRIAGE). If two men exchange sisters, and if sons and daughters result from each union, then it would be natural for the boy cousins again to marry each other's sisters. This would result in a marriage between people who were doubly cross-cousins and, if persisted in from one generation to another, would create a permanent bond between the two branches.