Does Milk Matter? Genetic Adaptation to Environment: The Effect of Lactase Persistence on Cultural Change

Abstract

Considering diet as often a product of adaptation to geographic environment, this paper suggests that not only the amount of food (food abundance) is important, but what kind of foods people eat may also affect social change. One of the reasons for variation in diet is food intolerances as a result of adaptation to the environment. This paper investigates one case – lactase persistence. This trait is associated with different genotypes of the LCT gene. Lactase persistence is mostly spread among northern Europeans, and is also found among some African and Asian nomadic populations. Such a unique trait is usually explained in the gene-culture coevolution framework: selective pressure for it had to be followed by the expansion of dairy production and herding. Empirical analysis based on 78 populations reveals strong and positive association between a lactase persistent population and the distribution of emancipative values. The suggested causal mechanism is a change in demographic trends: the effect of lactase persistence on the emancipative values is mediated through historically lower fertility and lower child mortality rates. This demographic transition results in higher value of human life, formation of human capital, economic development and finally cultural change.