Twin Transitions

We provide a new explanation for sub-Saharan Africa’s slow demographic and economic change. In a model where children die from infectious disease, childhood health affects human capital and noninfectious-disease related adult mortality. When child mortality falls from lower prevalence, as in western Europe, labor productivity improves, fertility falls and the economy prospers. When it falls mainly from better cures, as in sub-Saharan Africa, survivors are less healthy and there is little economic payoff. The model quantitatively explains sub-Saharan Africa’s experience. More generally it shows that life expectancy at birth is a poor indicator of population health unless morbidity falls with mortality.