Is exchange universal?

"Arab marriage" fits into a set of facts that Claude Levi-Strauss called "m arriage of a close degree". On the basis of ethnological data concerning th e Arabs as well as Tuaregs, Ancient Greeks, etc., questions are raised abou t the universality of the rule of exchange formulated in Les structures ele mentaires de la parente, a rule that assigns descent a structurally determi nant role. New ways of formalizing data in terms of the circulation of bodi ly substances are used in an attempt to show that the aforementioned system s of kinship and marital alliance refer to ways of handling, structurally a nd cognitively the masculine/feminine opposition, ways that follow a ration ale not of exchange but of sharing.