In redheads, the mutated MC1R gene produces pheomelanin instead, a protein that accounts for the flaming hair, pale skin, and freckles that we associate with carrot-tops.
As redhead research progressed, researchers found that MC1R mutations also affected the perception of pain and the effectiveness of certain drugs meant to block or numb the sensation of pain.
A study headed by Dr. Edwin Liem at the University of Louisville in Kentucky found that redheads are more sensitive to hot and cold, and are hurt by the cold at temperatures nearly 11 degrees Fahrenheit warmer than others. This group of researchers is also responsible for the study on redheads and anesthesia and the recent one about dentist-related anxiety.
The problem is, in some studies, researchers find that redheads are more sensitive to pain, while others find they're less sensitive.
Contrary to Liem's work, another group of researchers, based at McGill University in Montreal, have found that redheads are less sensitive to electric shock pain and more sensitive to the effects of certain pain-killing drugs.
Jeffrey Mogil, director of the pain genetics laboratory at McGill, heads up this research, offered his thoughts on this apparent contradiction.
One part of the confusion, says Mogil, is that he tests with analgesic, or pain-reducing, medication, while Liem's Louisville studies test for anesthetic, or pain-numbing, drugs.
"They work in different ways in the body," Mogil says. "It's like comparing apples and oranges."
Concerning the different pain findings, he says, "It's perfectly possible that the neural circuitry underlying heat pain and electric shock pain is different and these two findings can happily coincide."
But the research Mogil is currently working on shows that "redhead" mice are less sensitive to all kinds of pain, thermal pain included, so it looks like the conflict won't be completely cleared up any time soon.
OK, so being resistant to the very drug that will save you from feeling unnecessary pain may not seem like a super power but, according to Dr. Elliot Krane, director of Pain Management Services at Lucile Packard Children's Hospital at Stanford in Palo Alto, Calif., this genetic glitch does have powerful implications for medicine.
"[It] goes way beyond redheads," he says. "For centuries, doctors observed drugs having varied effects on people ... and mindlessly chalked it all up to human variability."
But the MC1R research proves that our genes can preordain how drugs will react in our bodies. The study of this interaction between genes and drugs, called pharmacogenomics, is the cutting edge of drug research, according to Krane, and may one day lead to safer, person-specific prescriptions.
"It will be possible to tailor their dosage regiment to their genetic profile, improving drug efficacy while reducing adverse effects," Krane says. "All this is probably less than a decade from reality."
If this is the case, then -- through our genetic quirks -- redheads have inspired research that may one day lead to safer medicine. We may not fight crime but I like to think that in this small way, redheads are using their mutant powers for good.
You know, saving the world one traumatizing dentist visit at a time.