The concept of family extends across virtually all cultures and all documented time periods, and family structures organize groups as diverse as primitive hunter/gatherer communities and modern, industrial societies. The word family originally referred to a group of slaves, which marks this concept's early association with authority relations. But for modern societies, family has increasingly referred to a unit organized by love, marriage, and the blood ties that result from these customs.

Members of a family typically function according to their specific role in the unit. The roles that members play out in the family have to do with the division of labor, which results from both natural patterns (women bearing children) and cultural customs (such as the male's tradition of dominance in the industrial marketplace). Social scientists have argued that the family system enhances an individual's survival. For instance, scientists claim that...