Polygynous households

Commonespecially in sub-Saharan Africa, they are family units in which one man ismarried to more than one woman.  Polygynousextended households were probably a recurring feature of family life duringmost of human evolution. Persistent questions about such households in contemporarysociety included, for example, whether they involve more interpersonal cooperation (e.g., among co-wives), are beneficial for women and for the developing infant and child relative to monogamous families.  

See Nuclear family, Parenting