外刊阅读20240902｜如何提高世界智商

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People today are much cleverer than they were in previous generations. A study of 72 countries found that average IQs rose by 2.2 points a decade between 1948 and 2020. This stunning change is known as the “Flynn effect” after James Flynn, the scientist who first noticed it. Flynn was initially baffled by his discovery. It took millions of years for the brain to evolve. How could it improve so rapidly over just a few decades?

The answer is largely that people were becoming better nourished and mentally stimulated. Just as muscles need food and exercise to grow strong, so the brain needs the right nutrients and activity to develop. Kids today are much less likely to be malnourished than they were in past decades, and more likely to go to school. Yet there is no room for complacency .

Globally, 22% of under-fives—roughly 150m children—are malnourished to the point of stunting . That means their brains are likely to be stunted, too. Half the world’s children suffer micronutrient deficiency, which can also impede brain development. Poor nutrition and a lack of stimulation can translate into a loss of as many as 15 IQ points. This has woeful consequences: one study found stunting led to incomes being 25% lower. Damage incurred during the “golden window” of the first 1,000 days after conception is likely to be permanent.

The world grows enough food, but several obstacles stop nutrients getting into young brains. One is war. Families sheltering from shrapnel cannot venture out to plant or harvest, and some governments intentionally starve restive regions into submission. Another is disease. Hungry children fall sick more often, and the energy they spend battling bugs cannot be devoted to growing grey matter. Poverty is a big part of the problem. But global data from UNICEF, an aid agency, show that although half the children with very restricted diets (including no more than two food groups) are indeed from poor families, the other half are not. Other factors, such as poor eating habits, are also to blame.

Several tactics would work. The simplest is to fortify basic foods, such as flour, with micronutrients, such as iron, zinc and folic acid. This is cheap and can make a big difference. Adding iodine to salt has made cretinism (a severe form of mental retardation ) a thing of the past in places where it was once common, from China to Switzerland.