The concept of mariika (age sets; sing. riika ) is of central importance within Kikuyu society. Mariika provide a way of keeping track of groups of people (both male and female) who were circumcised in different years. The circumcision group (generation) is given a name that identifies it with a particular event or characteristic of the group. Members of a particular riika, circumcised at the same time, were given a rank in the age groupings. The rank defined the behavior of individual members within a riika and their behavior toward members of other age groups, both younger and older. The older a riika became, the more respect it was given. Mariika function as agents of gender-segregated social control.
A strong bond of friendship forms between members of the same riika during Irua (circumcision ceremonies) and continues as a form of mutual social aid throughout their lives. Younger Kikuyu, however, are usually circumcised in hospitals today, and have a much weaker concept of mariika than earlier generations. In place of Irua, modern young Kikuyu find peer bonds in the school setting. Furthermore, the strict social segregation between the sexes seems to be breaking down as young people of both sexes come into contact with one another in primary classrooms, on the playground, and through church activities.
In the past, the transition from one life stage to another in Kikuyu society was marked by rites of passage. Each stage was given a special name for both males and females. Stages of life for the Kikuyu included newborn, infant, uncircumcised boy or girl, circumcised boy or girl, married, married with children, and old age.
Political authority in precolonial Kenya was decentralized. No kings, chiefs, or bureaucratic institutions existed. For the most part, political authority was collective at every level, and decisions were generally reached by the oldest males of kin groups or political units in council. Although the councils made some important decisions for the group as a whole, their primary role was judicial—the settlement of disputes between kin groups. The collective prestige of the elders in council, as the representatives of tradition and the ancestors, gave their words weight and their decisions authority. Women also had a council, the function of which was to deal with domestic concerns, matters of the farms, and the discipline of female social and ritual life. Women were excluded from politics and were usually prevented from holding rights in land.
The imposition of foreign rule on the Kikuyu drastically altered their social and political structures and disrupted their traditional ways of life. European settlement policies had an even more drastic effect on the Kikuyu as land was virtually taken away from thousands of resident Kikuyu without adequate compensation.