Introduction

Africa is the continent where the earliest remains of the human race have been found. Africa's agriculture is very old, dating back at least 5,000 years in the case of yam cultivation in the "Yam Belt" of Nigeria and Cameroon. African agriculture appears to be singularly resistant to change. Its crops and tools are largely the same as those used by farmers thousands of years ago. Techniques and practices of tilling the soil encountered in African villages date back many generations. Attempts from outside to impose change at a more rapid pace have invariably deceived their proponents. An observation about low-resource agriculture in Africa frequently made by economists is that factor (or input) productivities are low. If this is true of all factors, then the scope for factor substitution is very limited, and technological change raising the productivities of land, labor, and other factors would seem to be a necessary condition for achieving sustained increases in food production.