Too hot to work? Or too sick to grow?
Why do tropical countries tend to have lower average IQs and economic growth rates? In a novel study, Professor Jakob Madsen contends that a high burden of parasitic and infectious diseases (PID) and iron and iodine deficiency (IID) significantly slows the cognitive development of children, with important implications for public policy design.
IQs vary substantially across nations, with the average IQ in many tropical countries often found to be below 70. While such variations have traditionally been attributed to differences in the quality of schooling and inherited ability, recent medical research has suggested that a high prevalence of PIDs (such as hookworm, tapeworm, malaria and giardia) and IID, especially in utero and early childhood, significantly impairs children’s cognitive development and their cognitive ability during adulthood.
In a novel study, Professor Jakob Madsen tests whether cross-country variations in the burden of PID-IIDs in infancy and in utero can explain differences in cognitive ability around the globe, and whether cognitive ability can also account for variations in nations' productivity. Significantly, he finds that both PID-IID prevalence and cognitive ability are highly influential determinants of average IQ and, consequently, productivity. Together, this reveals that a high burden of PID-IIDs within a nation impairs children’s cognitive development, and in turn hinders growth.
For tropical nations, this is significant because it suggests that being located in a tropical area is a major obstacle for – but not a permanent impediment to – economic progress and prosperity. Most importantly, it shifts attention from more traditional policy responses (such as investments in education and skills programs, which remain important) to highlight the critical role that public health measures, including health campaigns, vaccination programs and the provision of mosquito nets, clean water and mineral and iron fortified food, play in boosting cognitive ability and economic growth in tropical areas. Given that many of these interventions are inexpensive, progress remains readily achievable with the right policy response.
Download the paper here