kinship

Kinship is one of the main organizing principles of human society, and kinship systems have been extensively studied by social anthropologists , for whom they are of particular importance because of their primacy in non-state societies. Kinship systems establish relationships between individuals and groups on the model of biological relationships between parents and children, between siblings, and between marital partners. Relationships established by marriage , which form alliances between groups of persons related by blood (or consanguineous ties), are usually referred to as affinal relationships. Some social scientists make a distinction between the study of kinship and the study of affinity. All such studies depend on the assumption that these relationships are systematic, entailing the observation of norms relating to behaviour between those related by kin or affinity. The relationships between parents and children (and by extension between grandparents and grandchildren) determine modes of inheritance as well as the overall political relationships between generations. Like links between siblings, the parent and child dyad can be crucial in establishing incest rules, which determine not only sexual relationships but also the rules underlying affinity, by denoting prohibited or prescribed marital partners. As the social relationships between husband and wife set up relationships between their respective consanguineous groups, the entire complex of kinship and affinal relationships can be seen to be fundamental to the analysis of political, economic, and social relations in non-state societies.

It should be noted that actual biological relationships are not necessary for status within a kinship system to be established. For instance, it may be more important to establish that a child has a social father, who will take responsibility for its welfare and have a right to the product of its labour, than to find out who the biological father might be. Nevertheless, most kinship systems do operate to establish rights in the sexual, reproductive, economic, and domestic services of women. In patrilineal societies, where sons inherit from their fathers, all these rights in women rest with the father until a girl marries, at which point they pass in totality to her husband. Matrilineal societies, on the other hand, focus on the importance of the sibling group. Inheritance passes from mother's brother to sister's son-in other words from uncle to nephew. The variety of ways in which this is organized have been referred to as solutions to the ‘matrilineal puzzle’. In the basic forms it means that brothers have rights over their sisters until they marry. At this point they retain reproductive rights, thus controlling their sisters' sons for inheritance purposes; however, sexual rights pass to the husband, as may rights to domestic services. Economic rights to the products of the sister's labour are likely to remain with the brother or sibling group.

Inheritance apart, kinship and affinity rules may also affect residence, relationships between individuals, modes of address, and various other economic and political behaviours. The rules themselves have been investigated through the study of genealogy, kinship terminology, marriage preferences and cycles of social reproduction. Within social anthropology, kinship theories tend to be grouped according to the relative emphasis they place on rules of descent or rules of affinity. In other words, they concentrate on either parent and child relationship rules or on the bonds between groups established through marriage.

Between the 1930s and 1960s, descent theory was predominant, associated largely with the work of Africanist anthropologists, such as Meyer Fortes , and the theoretical work of A. R. Radcliffe-Brown . Descent theorists suggest that kinship systems function to make sure that lineage groups persist over time as political entities. This means that relationships within lineage groups must be established and maintained through actual or fictional descent links traced through either or both parents. Parent-child and sibling bonds are therefore the focus of attention. Descent and succession are stressed in these studies, which are also highly empirical and related to functionalist theory, entailing that, for descent theorists, kinship systems exist in order to allocate rights and duties in societies.

Alliance theory is more theoretical, being interested in how the rules setting up links between groups through marriage are generated. Marriage and incest rules are therefore central. This means that, for alliance theorists, kinship systems exist in order to generate marriage possibilities or impossibilities. Much of this perspective is derived from the work of Claude Lévi-Strauss, who designated kinship systems as being either ‘elementary’ or ‘complex’. In the former case, a spouse is selected according to social rules, whereas in the latter the marriage partner is not determined by structural rules but rather by individual choice. However, these are abstract principles rather than descriptions of empirical reality: in practice, all societies have incest rules that define marriage partners according to elementary structures, and all have complex aspects that allow for a measure of situational choice.

In the 1960s and 1970s, controversy between alliance and descent theorists was heated, being part of the debate between functionalist and structuralist schools in social anthropology. Since then the discussion has cooled, and it is now generally acknowledged that the difference lies more in the level of theory applied, than in either any fundamental difference in concrete kinship systems or necessary adherence to a particular theoretical perspective.

Almost any of the works of Rodney Needham provide a good entry into the relevant anthropological literature (see, for example, Rethinking Kinship and Marriage, 1971, or Remarks and Inventions: Skeptical Essays about Kinship, 1974). See also family, sociology of.