Why polyandry fails: Sources of instability in polyandrous marriages

Polyandry has long been viewed as an anomalous form of marriage that raises fundamental questions about variability in human kinship systems. This paper integrates and evaluates a set of hypotheses derived from sociocultural anthropological and evolutionary biological theories of polyandry against data collected on the Nyinba, a well-studied ethnically Tibetan population living in northwestern Nepal. In this population, polyandry is fraternal; it is the normative form of marriage and highly valued culturally. Nonetheless, certain polyandrous marriages fail-men occasionally leave their natal households and abandon their joint marriages. In exploring the reasons for these marital breakdowns and the characteristics of men who instigate them, this paper offers a new perspective on the presumed contradictions of polyandry and a more fruitful approach to understanding how polyandrous practice comes to be perpetuated from one generation to the next. It also contributes to discussions about how sociocultural and evolutionary perspectives may provide complementary viewpoints for ethnographic data analysis.