It was a stroke of serendipity that may one day help those who hide under comb overs or wear wigs: scientists studying how mice bowels react to a stress-reducing chemical have inadvertently discovered a cure to baldness. But unfortunately, it looks like this cure won’t apply to genetic baldness, which is by far the main cause of most hairless pates. Still, researchers hope the lucky find will eventually be used to battle at least some of the bare heads of humans.

The story begins with mice that were genetically modified to produce too much corticotrophin-releasing factor, or CRF–a type of stress hormone. Normally, as these stressed-out rodents age, their backs lose hair. But a group of researchers from the Veterans Administration and the University of California at Los Angeles didn’t care about hair, they just wanted to study the effects of a chemical on the modified mice.

Researchers at the Salk Institute developed a peptide called “astressin-B”, which blocks the action of CRF, and the teams injected the peptide into the bald mice. They weren’t thinking about baldness at all — they wanted to test whether the ...