The African Slave Trade and the Curious Case of General Polygyny

General polygyny -- near universal marriage and polygyny -- is common in Africa. But why would men marry n wives for 1/n:th of the time instead of monogamously? Downsides include prolonged bachelorhood and a high degree of step-parenting. We point to the African slave trade which disproportionately removed young men, thus allowing old men to take young wives. Modeling endogenous social stigma, we argue that this temporary perturbation permanently changed the equilibrium to one where all men marry late and polygynously. Data are supportive: polygyny in Africa delays first marriage for men, raises under-five mortality, but does not predict life-long bachelorhood.