The key to maintaining this ecological and economic equilibrium was mobility. As long as land was abundant, more land could be gradually brought into the farming cycle to accommodate the slowly growing populations. But in most of Sub-Saharan Africa the scope for further expansion of crop land has drastically narrowed. Women's Time, and Their Role in Rural Production and Household Maintenance Systems. But the burdens on rural women are increasing, as population growth outpaces the evolution of agricultural technology and growing numbers of men leave the farms for urban and industrial jobs.
Many factors underlie the persistence of very high human fertility rates.
The fundamental problem is low demand for fewer children. Environmental degradation, agricultural problems, food insecurity and poverty, and the heavy work burdens of woman all play a part in this respect. High infant and child mortality rates are a major factor explaining the persistent high demand for large number of children in Africa. Where girls are kept our of school to help with domestic tasks, this negatively affects their fertility preferences and their ability to make informed decisions about family planning once they reach childbearing age. Land and Tree Tenure Systems.