ABSTRACT
The story of human origins summarised in the last chapter is clearly that of ‘Out of Africa’. Why was that continent humanity’s nursery?
Africa today has a more varied range of ecosystems than any other continent (Figure 1.4). Spanning 70 degrees of latitude, 35 either side of the Equator, it encloses a more or less symmetrical set of climatic zones and their associations of natural vegetation. At least, that is the impression given by small-scale ecological maps in school atlases. In truth it is the most ecologically varied on any scale of all continents. Figure 10.1 reveals one reason why this is so. Despite much of it being a low dome rising imperceptibly from its coastline to regional swells 1 to 1.5 km high, sudden changes in topography interrupt Africa’s general shape. Superimposed upon it are several large upland areas and intervening basins. The most striking feature of all is a huge cleft with high flanks that runs in a curved and branching form from Mozambique to the Red Sea and terminates at the Gulf of Suez. This East African Rift system sharply divides the continent into two regional climate systems.
