Where has polyandry been studied most closely?

Polyandry, the marriage of a woman to two or more men simultaneously, has been studied most closely in two primary regions: the Plateau of Tibet—a region spanning parts of India, Nepal, and the Tibet Autonomous Region of China—and the Marquesas Islands in the South Pacific.1

Additionally, the Toda people of the Nīlgiri Hills in southern India are well-documented for their practice of polyandry, where several men, typically brothers, share one wife.2

While historically considered rare, recent anthropological research has identified 53 additional nonclassical societies across the globe that practice various forms of polyandry, ranging from formal marriage to informal arrangements where multiple men are recognized as co-fathers. The practice is generally understood as a social response to specific environmental and economic conditions, such as sex ratios, male mortality, and social stratification.1