The analysis of our own nuclear family structure reveals certain patterns of differentiation that we also see in other societies if we clearly distinguish the nuclear family from the extended kinship groupings in which, in a great many societies, they are incorporated. Parsons has pointed out that in this particular instance it is fruitful to begin analysis with the more highly differentiated social system of the United States, rather than the so-called "simple" nonliterate societies, because in our society the nuclear family is structurally isolated from extended kin solidarities and functionally differentiated from other systems. But the nuclear family is not something characteristic only of our society. Murdock, for instance, has stated flatly that it is a discernible functioning group in all societies entering his sample, and there have been only one or two exceptions reported in the entire anthropological literature.'