Photo Illustration: Joe Zeff Design, Inc.
I wonder, now, why I never asked the question: Does it hurt? My mother was dying of breast cancer, but she didn't talk about her pain. At least not to me. Shortly after her funeral, though, one of her supposed friends remarked (with a good deal of scorn) that Mom had driven her crazy with nonstop complaining.

Oh, really? Can't complain, even when you feel like the pain is killing you?

It took me years (okay, decades) to stop fuming over that spectacularly insensitive remark. I asked myself, "What if my mother had been a man?" Would her friend have sympathized? Men have long been thought (and expected) to be more stoic. But are they really better at handling pain? Or are men and women wired to feel it differently?

The scientific consensus on that last question is yes, thanks in large part to Jeffrey Mogil, PhD, director of the pain genetics laboratory at McGill University in Montreal. His work on pain is leading to new treatments targeted to a patient's genetic makeup, the holy grail of a hot new field called pharmacogenetics.

Mogil first turned heads in the scientific community in 2003 when he identified a gene that influences receptivity to painkillers—but only in women. His team of researchers found that redheaded, fair-skinned women, in particular, who have a variant of that gene (melanocortin-1, which happens also to be a determinant of hair color) got much more relief from a class of painkillers that includes Talwin and Stadol than other women, while the drugs had only a modest effect on all the men. "I think ultimately we're going to find that there are simply different neural circuits for men and women," Mogil says. "The implications of that are pretty amazing, right? Because it suggests that if you develop a drug based on a protein in the male pathway, that drug will only kill pain in men and not women. And if you develop a drug that's based on the protein in the female pathway, that drug would only kill pain in women and not men. So you would have pink and blue pills for pain. Imagine the marketing campaign!"

Mogil lights up as he tells me this. We are walking through his comfortably low-tech laboratory at McGill—not much in the way of fancy scopes or imaging equipment—manned by a smattering of lab technicians and earnest graduate students. Mogil is a disarmingly cheerful man, something of a surprise considering that he spends his days thinking about pain. He proudly points to a crayon portrait of him at work by his son, then 6, and to the coffeemaker he scored for the lab's "conference-slash-lunchroom." Then he opens another door, puts a finger to his lips, and shows me his research subjects, cages full of contented-looking mice. I am reassured to learn that most of the testing brings them only to the threshold where they begin to sense pain, not beyond. He takes my palm and prods it gently with a thin wire on a tool called a von Frey filament, then with another, sharper wire, until I pull my hand away. Once the mouse flinches and begins to lick its paw (more urgent licking equals more pain), the testing is over. The lab technician notes the response on a computer grid and returns the mouse to its cage.

This is, I learn, an equal-opportunity laboratory for male and female rodents: a testament to Mogil's conviction that pain must be studied in women as well as men. By working with both sexes in his laboratory, he has bucked a tradition in medical research based on a false assumption that females show too much variability in their responses due to hormonal cycling. The focus on males seems ridiculous to him, because the vast majority of clinical pain patients are women. "Women are more sensitive to pain than men," he says. "They have a higher ability to discriminate among different levels of pain." Some syndromes, including migraine and fibromyalgia, "have very, very skewed ratios, up to nine to one in favor of women."