Basic to both Industrial and Foraging societies. Both kinds of societies require great mobility. Industrial society mobile because labor is purchased for cash. Individuals not tied to land or single immobile resource. Families of procreation set up their own, independent households independent of parents.
Bands are fluid with changing membership.
In harsh areas, like Great Basin deserts occupied by Shoshone Indians, bands split into nuclear families to forage independently and reunite with band when seasons and resources permit. Like industrialized societies, mobility is main factor in deciding emphasis on nuclear family. Foragers not tied to one territory or single resource. Descent groups provide mechanism for inheritance of property. In non-industrial societies, marriage often serves to join two kin groups in an economically, socially or politically relationship beneficial to both.