In sociobiology and zoology, researchers use polygamy in a broad sense to mean any form of multiple mating.Worldwide, different societies variously encourage, accept or outlaw polygamy.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.
Marriage is the moment at which a new household is formed, but different arrangements may occur depending upon the type of marriage and some polygamous marriages do not result in the formation of a single household.
In many polygynous marriages the husband's wives may live in separate households Polyandry is the practice wherein a woman has more than one husband at the same time.
Polyandry is much less popular than polygyny and is illegal in virtually every state in the world. For example, in the Himalayan Mountains polyandry is related to the scarcity of land; the marriage of all brothers in a family to the same wife allows family land to remain intact and undivided.
Polygyny is legally accepted in many Muslim majority countries and some countries with a sizeable Muslim minority; it is also accepted in some secular countries in varying degrees.
Polygyny is more widespread in Africa than in any other continent, especially in West Africa, and some scholars see the slave trade's impact on the male-to-female sex ratio as a key factor in the emergence and fortification of polygynous practices in regions of Africa.