Heritable IQ is Boosted by Environment, Just Like Height

hough it’s not easy to pinpoint the causes of the rise in IQ scores, it’s no paradox that a heritable trait can be boosted by changes in the environment. That’s what happened with height, a trait that also is highly heritable and has increased over the decades, and for some of the same reasons: better nutrition and less disease. Brains are greedy organs, consuming about a fifth of the body’s energy, and they are made of fats and proteins that are demanding for the body to produce. Fighting off infections is metabolically expensive, and the immune system of a sick child may commandeer resources that would otherwise go to brain development. Also helping with brain development is a cleaner environment, with lower levels of lead and other toxins. Food, health, and environmental quality are among the perquisites of a richer society, and not surprisingly, the Flynn effect is correlated with increases in GDP per capita.