Hunger makes the best sauce, goes the maxim. According to researchers at Yale Medical School, it may make quadratic equations and Kant’s categorical imperative go down easier too. The stimulation of hunger, the researchers announced in the March issue of Nature Neuroscience, causes mice to take in information more quickly, and to retain it better — basically, it makes them smarter. And that’s very likely to be true for humans as well.

Image Empty-stomach intelligence. Credit... Illustration by Leanne Shapton

A team led by Tamas Horvath, chairman of Yale’s comparative medicine program, had been analyzing the pathways followed in mouse brains by ghrelin, a hormone produced by the stomach lining, when the stomach is empty. To the scientists’ surprise, they found that ghrelin was binding to cells not just in the primitive part of the brain that registers hunger (the hypothalamus) but also in the region that plays a role in learning, memory and spatial analysis (the hippocampus).

The researchers then put mice injected with ghrelin and control mice through a maze and other intelligence tests. In each case, the biochemically “hungry” mice — mice infused with ghrelin — performed notably better than those with normal levels of the hormone. The finding was startling, but “it makes sense,” Horvath says. “When you are hungry, you need to focus your entire system on finding food in the environment.” In fact, some biologists believe that human intelligence itself evolved because it made early hominids more effective hunters, gathers and foragers.