Geological age of Africa

I, find it interesting the way African people live.
Most of the population in Africa live on plateaus (high plains), which are of altitudes in excess of 1000 meters above sea level. Altitude moderates temperature; consequently, although most of Africa is tropical (approximately 80% of Africa lies between latitudes 23 ½ degree north, the Tropic Cancer, and 23 ½ degrees south, the Tropic of Capricorn) the climate is quite moderate and not indicative of the tropics. In well-watered areas, dominant crops grown and animals raised are similar to those in temperate zones.