But Africa’s head start in our mutual story did allow it more time to develop something else that to this day holds it back: a virulent set of diseases, such as malaria and yellow fever, brought on by the heat and now complicated by crowded living conditions and poor health-care infrastructure. This is true of other regions—the subcontinent and South America, for example—but sub-Saharan Africa has been especially hard-hit, for example by HIV, and has a particular problem because of the prevalence of the mosquito and the tsetse fly.
