Anthropologist Jack Goody's comparative study of marriage around the world utilizing the Ethnographic Atlas demonstrated an historical correlation between the practice of extensive shifting horticulture and polygamy in the majority of sub-Saharan African societies. Drawing on the work of Ester Boserup, Goody notes that the sexual division of labour varies between the male-dominated intensive plough-agriculture common in Eurasia and the extensive shifting horticulture found in sub-Saharan Africa. In some of the sparsely-populated regions where shifting cultivation takes place in Africa, women do much of the work. This favours polygamous marriages in which men seek to monopolize the production of women "who are valued both as workers and as child bearers". Goody however, observes that the correlation is imperfect and varied, and also discusses more traditionally male-dominated though relatively extensive farming systems such as those that exist in much of West Africa, especially in the West African savanna, where more agricultural work is done by men, and where polygyny is desired by men more for the generation of male offspring whose labor is valued.