Redheads have long been portrayed in literature and art as strong-willed and fiery. Now there may be a scientific explanation for these traits. The key, according to researchers at McGill University in Montreal, is a gene that is linked both to red hair coloring and to higher levels of pain tolerance. It has been known since the mid-1990's that mutations of the MC1R gene are responsible for hair color -- and fair skin and freckles -- in about 70 percent of redheads. But when Jeffrey S. Mogil and his colleagues at McGill set out to find a genetic link to pain inhibition, MC1R wasn't at the top of their list of targets. "We normally only get excited about genes in the brain when it comes to pain," he says. "This is in the skin." There was, however, a little-noticed paper that said MC1R was in fact expressed in the brain. It was enough of a clue to go on.

So, earlier this year, Mogil ran some mice through a battery of pain tests, using mice with the red-hair gene as his test group. (A collaborator in the Netherlands ran the same study with humans, giving them electrical shocks to the leg.) When animals and humans experience pain, their brains release natural opiates similar to morphine. In most cases, however, the MC1R gene produces a protein that interferes with the efficacy of those substances as well as of artificial painkillers. What Mogil found is that the variant of MC1R that causes red hair also appears to allow these opiates to work unimpeded. As a result, redheads can withstand up to 25 percent more pain than their blond and brunet peers do before saying "stop."

The research may give redheads something to brag about, but it could also lead to the development of better painkilling drugs and anesthesia. Redheads already require smaller amounts of analgesics to deal with pain; if scientists can reproduce the aspect of the mutated MC1R gene that makes this possible, it could help even those of us who weren't blessed with ginger locks.

Amy Sullivan