Long Run Health Effects of the Neolithic Revolution: The Natural Selection of Infectious Disease Resistance Working Draft C. Justin Cook∗ January 15, 2013 Abstract This paper argues that genetic differences arising since the Neolithic Revolution can explain variation in life expectancy before the advent of effective medicines and vaccines. The differential timing of the Neolithic Revolution, along with the varied distribution of domesticate animals, resulted in historical differences in the exposure to a class of infectious pathogens. This historical difference in disease environments led to differences in the natural selection of resistance. To measure the resulting genetic differences, we construct a measure of genetic variation within the human leukocyte antigen (HLA) system, a key component of the immune system. Our estimations show that a ten percent increase in HLA genetic diversity is roughly associated with a five percent increase in pre-medicinal life expectancy. JEL Classification: N30, I12, Z13. Keywords: Life Expectancy, Infectious Disease, Genetic Diversity, Neolithic Revolution, Natural Selection. ∗Postdoctoral Associate, Division of Health Policy and Management,Yale School of Public Health;60 College St., New Haven, CT 06510; e-mail:
[email protected]. 1 Introduction The role of infectious diseases in low income economies is devastating in both a humanitar- ian and, arguably, an economic sense. In the developed world the majority of diseases are associated with aging, e.g. cancer and heart disease, but in developing states preventable infectious diseases remain the primary cause of mortality (Cutler et al. 2006). Why are these diseases so prevalent and destructive in developing states? The most obvious answer is tied to the socioeconomic conditions that continually plague inhabitants of less devel- oped countries.