The African continent is distinguished by a much higher fertility rate than other regions. Fertility in Africa has remained almost constant at slightly over six children per woman on average, while important declines have occurred elsewhere over the past 25 years. High fertility in Africa is often attributed to poor diffusion of family planning, early marriage, and low female educational attainment, but other cultural and economic factors are involved. The significant decline of infant mortality over the past several decades has produced growth rates never before observed. Africa's very young populations may be at the origin of uncontrollable political disorder, as young persons with bleak prospects fall easy prey to ethnic, religious, and political extremism. Demographic growth has become an additional barrier to development. High fertility is tolerated or encouraged as constituting a cultural trait, but the resulting population growth is not a cultural trait. Demographic pressure has increased environmental problems in many regions. It is estimated that over ten million rural residents of the Sahel have been affected by soil degradation. The per capita availability of arable land fell from one-half to one-third hectare between 1965 and 1987. Shortages of firewood and water have become more common. The relationship between demographic growth, environmental crisis, and poverty in the countryside depends on other factors such as production techniques, modes of access to land and water, and the degree of security of land tenure. Population pressure was not the initial factor that disturbed the balance of the traditional societies, but it exacerbated the effects of other forces such as the introduction of cash crops and monetarization of the economy. Rural exodus and accelerated urban migration have been prompted in large part by the higher incomes and greater availability of services of all types in the cities. Achieving control of fertility in Africa will require stabilization of rural populations, territorial management, and reduction of disparities between rural and urban areas.