We hypothesize that the timing of the fertility transition is an important determinant of comparative physiological development. In support, we provide a model of long-run growth, which elucidates the links between population size, average body size and income during development....

Conventional R\&D-based growth theory suggests that productivity growth is positively correlated with population size or population growth, an implication which is hard to see in the data. Here we integrate microfounded fertility and schooling into an otherwise standard R\&D-based growth model....

We examine the long-run relationship between fertility, mortality, and income using panel cointegration techniques and the available data for the last century. Our main result is that mortality changes and growth of income per capita account for a major part of the fertility change...