Why Do IQ Scores Vary By Nation? Global differences in intelligence is a sensitive topic, long fraught with controversy and still tinged by the disgraceful taint of pseudosciences such as craniometry that strove to prove the white “race” as the most clever of them all. But recent data, perplexingly, has indeed shown cognitive ability to be higher in some countries than in others. What’s more, IQ scores have risen as nations develop—a phenomenon known as the “Flynn effect.” Many causes have been proposed for both the intelligence gap and the Flynn effect, including education, income, and even nonagricultural labor. Now, a new study from researchers at the University of New Mexico offers another intriguing theory: intelligence may be linked to infectious-disease rates. The Idea The brain, say author Christopher Eppig and his colleagues, is the “most costly organ in the human body.” Brainpower gobbles up close to 90 percent of a newborn’s energy. It stands to reason, then, that ...
