Racists ate it up and asked for second helpings. After all, here was hard scientific evidence that seemed to corroborate what they had always claimed: that some races were intellectually inferior to others. Their failure to prosper economically was rooted not in history, but in nature. “There will be plenty more results where these came from,” predicted the right-wing commentator John Derbyshire in the American conservative magazine National Review. Lahn also attracted support from the late Henry Harpending, a geneticist at the University of Utah and co-author of a controversial book arguing that biology could explain why Europeans conquered the Americas, and also that European Jews had evolved to be smarter on average than everyone else.
However, there were problems with Lahn’s findings. Even if his gene variants did show up with different frequencies in certain populations, it did not necessarily mean that they provided those who had them with a cognitive advantage. The variants were known to be linked to organs other than the brain, so if natural selection was taking place, maybe this was nothing to do with intelligence. Maybe the genes conferred some advantage that wasn’t related to the brain. The hypothesis needed more evidence.
Soon after the papers were published, the controversial Canadian psychologist John Philippe Rushton ran IQ tests on hundreds of people to see if the gene variants really did make a difference to intelligence or to brain size in those who possessed them. Try as he might, he couldn’t find any evidence that they did. They neither increased head circumference nor general mental ability.