A life-style. that apparently exists in all societies is marriage--a socially sanctioned u

nion between a woman and a man with expectation that they will play the roles of wife and husband. After studying extensive cross-cultural data, the anthropologist George P. Murdock concluded that reproduction, sexual relations, economic cooperation, and the socialization of offspring are functions of families throughout the world. We now recognize that Murdock overstated the matter, since there are a number of societies--for instance, Israeli kibbutz communities--in which the family does not encompass all four o[ these activities. What Murdock describes are commonly encountered tendencies in family functioning in most cultures.

Societies differ in how they structure marriage relationships. Four patterns are found: monogamy, one husband and one wife are found; polygyny, one husband and two or more wives; polyandry, two or more husbands and one wife; and group marriage, two or more husbands and two or more wives. Although monogamy exists in all societies, Murdock discovered that other forms may be not only allowed but preferred. Of 238 societies in this sample, only about one-fifth were strictly monogamous.

Polygyny has been widely practiced throughout the world. The Old Testament reports that both King David and King Solomon had several wives. In his cross-cultural sample of 238 societies, Murdock found that 193 of them permitted husbands to take several wives. In one-third of these polygynous societies, however, less than one-fifth of the married men had more than one wife. Usually it is only the rich men in a society who can afford to support more than one family.

In contrast with polygyny, polyandry is rare among the world's societies. And in practice, polyandry has not usually allowed freedom of mate selection for women; it has often meant simply that younger brothers have sexual access to the wife of an older brother. Thus where a father is unable to afford wives for each of his sons, he may secure a wife for only his oldest son.