Survival of the foolest: population dynamics, income policies, and IQ trends

Abstract

This paper examines how different income distribution policies may influence the future distribution of intelligence quotient (IQ) in a population. Using a multi-period individual-based simulation model, and assuming the inheritance of IQ from one generation to the next, we report simulation results under five different income distribution policies: egalitarian, quasi-egalitarian, liberal egalitarian, liberal quasi-egalitarian, and libertarian. Our model has two main assumptions on the fertility rate in line with the findings from the relevant literature: (i) there is a negative correlation between intelligence and fertility (i.e., dysgenic fertility) and (ii) there is a U-shaped correlation between income and fertility. Our results indicate that overall intelligence in a population always tends to decline in the presence of dysgenic fertility. The quasi-egalitarian income distribution policy performs the best in decelerating that decline in IQ levels, even when intelligence has a significantly higher influence on the fertility rate than income. On the other hand, if dysgenic fertility can be suppressed to a sufficient extent, then the libertarian income distribution policy is revealed to be the best policy to improve the population’s overall intelligence.