Cross Cousin Marriage

The presence of elaborate systems for arranging and regulating marriages in widely different cultures suggests to anthropologists that marriage often serves to create and maintain alliances and exchanges between groups. Many of these exchanges are made on an ad hoc basis to cultivate strategic relationships, such as "political marriages" between the children of important leaders. More extensive, stable, and permanent transgeneration ties among allies can be developed ed by a widely instituted system of cross-cousin marriage. Relevant rules specify a man must or should marry either:

his mother's brother's daughter, matrilateral cross cousin,
father's sister's daughter, patrilateral cross cousin, or
under special circumstances, a relative who is simultaneously his mother's brother's and father's sister's daughter, bilateral cross cousin.

These simple matrilateral and patrilateral relationships can be diagrammed as follows:

Standard Cousin Relationships

Ego's cross cousins (in yellow) are distinguished from his parallel cousins (in green) as the children of opposite and same sexed siblings, respectively. Patrilateral cousins are related to Ego on his father's side of the family. Matrilateral cousins are related to ego on his mother's side of the family.

The same relationships would of course obtain for a female ego. However, cross cousin marriage rules per se are specified from a male perspective. Thus for matrilateral cross cousin marriage, a man marries his mother's brother's daughter, although his wife is marrying patrilaterally, i.e., to her father's sister's son. In the patrilateral case, a man marries his father's sister's daughter and a woman, her mother's brother's son.

Male and Female Perspectives

While not necessarily recognized as such, matrilateral and patrilateral cross cousins are present in every kinship network, bilateral cross cousins occur only in special marriage situations, where two men marry each other's sisters.

Bilateral Cross Cousins

In the above diagram, two men (1 and 3) marry each other's sisters (2 and 4), a practice referred to as direct exchange marriage. (Note that marriages are indicated by lines joining partners from below rather than by equal signs.) Couple 2 and 3 beget Ego. Couple 1 and 4 have two children, 5 and 6, who assume a compound relationship to Ego. In one direction they are his father's sister's children; in another, they are his mother's brother's children. (Each pathway is indicated in the diagram in yellow.) As such they are related to ego both patrilaterally and matrilaterally and are therefore termed his bilateral cross cousins.

The widespread presence of cross cousin marriage in its varous forms has been of special importance to the structuralist anthropologist, Claude Levi-Strauss, and to his formulation of alliance theory (Levi-Strauss 1969). He views marriage as a form of exchange that simultaneously expresses differences between groups and unites them into coherent social systems. His observations focus on the significance of the three alternative marriage rules for the emergence of different social dynamics.

Bilateral cross cousin marriage results in a system of direct exchange marriage between paired lineages.
Matrilateral cross cousin marriage results in a system of indirect exchange marriage between an indefinite number of descent lines, also called asymmetrical exchange.
Patrilateral cross cousin marriage results in a system which can be viewed as a combination of both of the others systems.