Young demographics. Compared with other regions of the world, Africa has a much younger median age, which means African governments aren't as burdened by elderly populations and pension plans. It also means that Africa has a young, vibrant workforce, Seruma says. Africa's most populous nation is Nigeria, which Seruma accounts for about a quarter of Africa's total population. Nigeria's median age is 19 years old. Compare that with 37 in the United States, 40 in the U.K., and 45 in Japan.