Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
IQ scores differ substantially across nations. This study argues that cross-country variations in IQ scores, to a large extent, reflect the burden of parasitic and infectious diseases (PIDs) and iron and iodine deficiency (IID) in infancy and in utero. Furthermore, it is shown that the prevalence of health insults, through the channel of cognitive ability, is influential for the level as well as the growth in productivity across the world. Using data for 181 countries and an instrumental variable approach, regressions reveal that the prevalence of PID–IIDs is influential for growth and income inequalities globally.