polyandry

Polyandry is a mating system in which a female has sexual relationships with multiple male partners, often within a single breeding season. It can be social polyandry, where a female cohabits with several males who may jointly contribute to care, or genetic polyandry, where offspring are sired by more than one male. The opposite of polyandry is polygyny, where males mate with multiple females.

Across the animal kingdom, polyandry occurs in varying forms and frequencies. It is relatively common in birds, where females may pair with several males while males provide parental care or defend territory. Notable examples include species such as jacanas and some shorebirds, as well as red phalaropes. In other groups such as insects and crustaceans, polyandry also occurs and is often driven by sperm competition and genetic benefits to offspring. In mammals and many other taxa, polyandry is less frequent but documented in specific species and ecological contexts.

In humans, polyandry is rare and typically context-dependent. Ethnographic and anthropological accounts include cases of fraternal polyandry, where a woman is married to brothers who share resources and parental duties, notably among some Himalayan communities. Genetic studies in humans reveal multiple paternity in some families, indicating that polyandrous unions can occur under certain social arrangements.

Genetically, polyandry results in offspring sired by multiple males, which can enhance genetic diversity and provide reproductive insurance. It can also complicate paternity and parental investment decisions, leading to varying social and evolutionary consequences for both females and males.