The individual is a member of two divisions of society throughout life. The first and more definite grouping is the kindred, a vertical division of society, based either on recognized lineal descent from a common ancestor or adoption. Descent is reckoned primarily through the patrilineal line, though the matrilineal line determines many social relations and activities. The second grouping is the generations, a horizontal division based on age, cutting across kindred. Five generations may live during the lifetime of the individual, but only three function actively in the life of society—the children, the adolescents and young married people who make the body of the community, and the older people who direct the welfare of society.

Each individual living a full span of life passes through these three periods and in each his position in the family and community changes. In childhood, he has few responsibilities. Through adolescence, he is a junior member of his family group and of society, a worker providing food, doing most of the menial labor, and caring for his elders. During this period marriage usually takes place and the individual establishes his own family. In the last period, the individual no longer does the manual labor but becomes head of his household and shares in the direction of the kindred and community affairs. The passage from one period to the next is marked by rites or initiatory preparations which allow the individual to pass safely into the following phase of life.