Why Is Polygyny More Prevalent in Western Africa? An African Slave Trade Perspective

Polygyny rates are higher in western Africa than in eastern Africa. The African slave trades help explain this difference. More male slaves were exported in the transatlantic slave trades from western Africa, while more female slaves were exported in the Indian Ocean slave trades from eastern Africa. The slave trades led to prolonged periods of abnormal sex ratios, which affected the rates of polygyny across Africa. In order to assess these claims, we present evidence from a variety of sources. We find that the transatlantic slave trades have a positive correlation with historical levels of polygyny across African ethnic groups. We also construct an ethnic group level data set linking current rates of polygyny with historical trade flow data from the transatlantic and Indian Ocean slave trades. We find that the transatlantic slave trades cause polygyny at the ethnic group level, while the Indian Ocean slave trades do not. We provide cross-country evidence corroborating our findings.