The Role of Lactase Persistence in Precolonial Development

Abstract

This paper establishes a link between natural selection since the Neolithic Revolution and economic conditions in the precolonial era. The ability to digest milk, or to be lactase persistent, is conferred by a gene variant, which is unequally distributed across the Old World. Digesting milk conferred qualitative and quantitative advantages to early farmers' diets, which ultimately, led to differences in the carrying capacities of respective countries. It is shown through a number of specifications that country level variation in the frequency of the ability to consume milk is positively and significantly related to population densities in 1500 CE; specifically, a one standard deviation increase in the frequency of lactose tolerant individuals (roughly 24 percentage points) is associated with roughly a 40 percent increase in precolonial population density. This relationship is robust to a large number of sample specifications and potentially omitted variables. Furthermore, a causative effect of dairying on population density is confirmed with the use of an exogenous, environmental instrument, solar radiation.