For decades, scholars have puzzled over why polygyny in Africa is concentrated in the continent's western countries -- Guinea, Togo, and Mali, among others. There are competing theories, rooted in variables such as relative infant mortality rates and the agricultural roles women play in different parts of Africa. A new study, however, argues that the answer may be found somewhere else, darker and uglier: the slave trade. 

The trans-Atlantic trade wildly disrupted West Africa's gender ratios,argue John Dalton and Tin Cheuk Leung, economists from Wake Forest University and the Chinese University of Hong Kong, respectively.

West African slaves were mostly sent to the New World, where buyers strongly preferred men capable of performing backbreaking tasks on plantations. By contrast, buyers in slave trades centered on the Indian Ocean and Red Sea were often looking for women who could work as domestic servants or concubines.