In such cases, the deceased man's heir may inherit his assets and wife; or, more usually, his brothers may marry the widow.This provides support for the widow and her children (usually also members of the brothers' kin group) and maintains the tie between the husband and wives' kin groups.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 sought to monopolize the production of women "who are valued both as workers and as child bearers".This is a form of de facto polygyny that is referred to as concubinage.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.When a woman is married to more than one husband at a time, it is called polyandry.
For men, the benefits of polygyny are that it allows them to have more children, may provide them with more productive workers (where workers are family), and allows them to establish politically useful ties with a greater number of kin groups.
The sororate is like the levirate, in that a widower must marry the sister of his dead wife.
The wife's family, in other words, must provide a replacement for her thus maintaining the ties between them.
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.