Diagnosing deep roots of development: Genetic, disease, and environmental factors

We examine the association between real GDP per capita and the ACP1 genetic adaptation to disease and ultraviolet radiation environment.

To our knowledge this paper is the first to explore the link of a specific genetic marker to development. The markers for the genetic adaptation we explore are the prevalence of acid phosphatase locus 1 (ACP1) A, B and C alleles in human populations. The assembled data on the frequencies of ACP1*A, ACP1*B, and ACP1*C alleles is a compilation of 153,090 global genotypes (the largest such genetic undertaking ever), in the populations of 117 countries. The specific mechanism we propose rests on three mutually reinforcing linkages. Ultra-violet radiation (UVR) exposure lowers folate, increases oxidative stress, and increases immune suppression (switch from pro- to anti-inflammatory immune system). Lower folates raise ACP1, which in turn combats oxidative stress (by raising glutathione reductase) and strengthens the switch from pro- to anti-inflammatory immune system. In order to defend against DNA and tissue damage, equatorial populations have been under substantial selection pressure. Alleles that increase anti-inflammatory responses were positively selected for, while pro-inflammatory alleles were selected against, with considerable behavioral and reproductive cost. The mechanism that is in operation is that geography selects disease environment; disease environment results (through natural selection) in genetic adaptation; the genetic adaptation has productivity implications. The obvious endogeneity issues implied are extensively tested and controlled for through instrumental variable estimation (IV) strategies in the paper.

We find a strong impact that varies across the A, B, and C alleles. The result is robust to controlling for reversal of fortunes, migration, and potential endogeneity of the genetic adaptation. It is also robust to controlling for other potential deep roots of development, geography, early adoption of technology, the population proportion that is European, and genetic diversity, as well as a range of factors held to be relevant by the economic growth literature. Policy prescriptions point to the importance of protection against ultraviolet radiation, control of tropical diseases, and the possible use of folic acid therapy and nutirent supplements in clearly identifiable geographic areas.

¹Measurement follows the Cummins et al (2010) method. Measures are for technology adoption in agriculture, communications, transportation, military and industry individually, as well as in terms of a summary "average" measure across all sectors.