In cultural anthropology, reciprocity refers to the non-market exchange of goods or labour ranging from direct barter (immediate exchange) to forms of gift exchange where a return is eventually expected (delayed exchange) as in the exchange of birthday gifts. It is thus distinct from the true gift, where no return is expected. When the exchange is immediate, as in barter, it does not create a social relationship. When the exchange is delayed, it creates both a relationship as well as an obligation for a return (i.e. debt). Hence, some forms of reciprocity can establish hierarchy if the debt is not repaid. The failure to make a return may end a relationship between equals. Reciprocal exchanges can also have a political effect through the creation of multiple obligations and the establishment of leadership, as in the gift exchanges (Moka) between Big Men in Melanesia. Some forms of reciprocity are thus closely related to redistribution, where goods and services are collected by a central figure for eventual distribution to followers. Marshall Sahlins, an American cultural anthropologist, identified three main types of reciprocity (generalized, balanced and negative) in the book Stone Age Economics (1972). Reciprocity was also the general principal used by Claude Lévi-Strauss to explain the Elementary Structures of Kinship (1949), in one of the most influential works on kinship theory in the post-war period. The history of the "norm of reciprocity" in European economic thought Annette Weiner argued that the "norm of reciprocity" is deeply implicated in the development of Western economic theory. Both John Locke and Adam Smith used the idea of reciprocity to justify a free market without state intervention. Reciprocity was used, on the one hand, to legitimize the idea of a self-regulating market; and to argue how individual vice was transformed into social good on the other. Western economic theorists starting with the eighteenth century Scots economists Sir James Stuart and Smith differentiated pre-modern natural (or self-subsistent) economies from civilized economies marked by a division of labour that necessitated exchange. Like early sociologist Émile Durkheim, they viewed natural economies as characterized by mechanical solidarity (like so many peas in a pod) whereas the civilized division of labour made producers mutually dependent upon one another resulting in organic solidarity. These oppositions solidified by the late nineteenth century in the evolutionary idea of primitive communism marked by mechanical solidarity as the antithesis and alter ego of Western "Homo economicus".