FIGURE 7.23 Population pyramids for Nigeria and South Africa. Note that the two pyramids are at the same scale. Nigeria had a population of 170.1 million people in 2012 and a growth rate of 2.6%, as indicated by its very wide pyramid base. It has the largest population on the continent, nearly twice that of Ethiopia, the second largest in terms of population. South Africa, on the other hand, has a population of 51.1 million and a growth rate of only 0.9%; its population is beginning to decline, as shown by the shrinking of the pyramid base. The decline is in part due to the AIDS epidemic.