What the Dog Saw

Strassmann, who teaches at the University of Michigan at Ann Arbor, is a slender, soft-spoken woman with red hair, and she recalls her time in Mali with a certain wry humor. The house she stayed in while in Sangui had been used as a shelter for sheep before she came and was turned into a pigsty after she left. A small brown snake lived in her latrine, and would curl up in a camouflaged coil on the seat she sat on while bathing. The villagers, she says, were of two minds: was it a deadly snake—Kere me jongolo, literally, “My bite cannot be healed”—or a harmless mouse snake? (It turned out to be the latter.) Once, one of her neighbors and best friends in the tribe roasted her a rat as a special treat. “I told him that white people aren’t allowed to eat rat because rat is our totem,” Strassmann says. “I can still see it. Bloated and charred. Stretched by its paws. Whiskers singed. To say nothing of the tail.” Strassmann meant to live in Sangui for eighteen months, but her experiences there were so profound and exhilarating that she stayed for two and a half years. “I felt incredibly privileged,” she says. “I just couldn’t tear myself away.”

Part of Strassmann’s work focused on the Dogon’s practice of segregating menstruating women in special huts on the fringes of the village. In Sangui, there were two menstrual huts—dark, cramped, one-room adobe structures, with boards for beds. Each accommodated three women, and when the rooms were full, latecomers were forced to stay outside on the rocks. “It’s not a place where people kick back and enjoy themselves,” Strassmann says. “It’s simply a nighttime hangout. They get there at dusk, and get up early in the morning and draw their water.” Strassmann took urine samples from the women using the hut, to confirm that they were menstruating. Then she made a list of all the women in the village, and for her entire time in Mali—736 consecutive nights—she kept track of everyone who visited the hut. Among the Dogon, she found a woman on average has her first period at the age of sixteen and gives birth eight or nine times. From menarche, the onset of menstruation, to the age of twenty, she averages seven periods a year. Over the next decade and a half, from the age of twenty to the age of thirty-four, she spends so much time either pregnant or breast-feeding (which, among the Dogon, suppresses ovulation for an average of twenty months) that she averages only slightly more than one period per year. Then, from the age of thirty-five until menopause, at around fifty, as her fertility rapidly declines, she averages four menses a year. All told, Dogon women menstruate about a hundred times in their lives. (Those who survive early childhood typically live into their seventh or eighth decade.) By contrast, the average for contemporary Western women is somewhere between three hundred and fifty and four hundred times.

Strassmann’s office is in the basement of a converted stable next to the Natural History Museum on the University of Michigan campus. Behind her desk is a row of battered filing cabinets, and as she was talking, she turned and pulled out a series of yellowed charts. Each page listed, on the left, the first names and identification numbers of the Sangui women. Across the top was a time line, broken into thirty-day blocks. Every menses of every woman was marked with an X. In the village, Strassmann explained, there were two women who were sterile, and, because they couldn’t get pregnant, they were regulars at the menstrual hut. She flipped through the pages until she found them. “Look, she had twenty-nine menses over two years, and the other had twenty-three.” Next to each of their names was a solid line of x’s. “Here’s a woman approaching menopause,” Strassmann went on, running her finger down the page. “She’s cycling but is a little bit erratic. Here’s another woman of prime childbearing age. Two periods. Then pregnant. I never saw her again at the menstrual hut. This woman here didn’t go to the menstrual hut for twenty months after giving birth, because she was breast-feeding. Two periods. Got pregnant. Then she miscarried, had a few periods, then got pregnant again. This woman had three menses in the study period.” There weren’t a lot of x’s on Strassmann’s sheets. Most of the boxes were blank. She flipped back through her sheets to the two anomalous women who were menstruating every month. “If this were a menstrual chart of undergraduates here at the University of Michigan, all the rows would be like this.”

Strassmann does not claim that her statistics apply to every preindustrial society. But she believes—and other anthropological work backs her up—that the number of lifetime menses isn’t greatly affected by differences in diet or climate or method of subsistence (foraging versus agriculture, say). The more significant factors, Strassmann says, are things like the prevalence of wet-nursing or sterility. But overall she believes that the basic pattern of late menarche, many pregnancies, and long menstrual-free stretches caused by intensive breast-feeding was virtually universal up until the “demographic transition” of a hundred years ago from high to low fertility. In other words, what we think of as normal—frequent menses—is in evolutionary terms abnormal. “It’s a pity that gynecologists think that women have to menstruate every month,” Strassmann went on. “They just don’t understand the real biology of menstruation.”

To Strassmann and others in the field of evolutionary medicine, this shift from a hundred to four hundred lifetime menses is enormously significant. It means that women’s bodies are being subjected to changes and stresses that they were not necessarily designed by evolution to handle. In a brilliant and provocative book, Is Menstruation Obsolete?, Drs. Elsimar Coutinho and Sheldon S. Segal, two of the world’s most prominent contraceptive researchers, argue that this recent move to what they call “incessant ovulation” has become a serious problem for women’s health. It doesn’t mean that women are always better off the less they menstruate. There are times—particularly in the context of certain medical conditions—when women ought to be concerned if they aren’t menstruating: In obese women, a failure to menstruate can signal an increased risk of uterine cancer. In female athletes, a failure to menstruate can signal an increased risk of osteoporosis. But for most women, Coutinho and Segal say, incessant ovulation serves no purpose except to increase the occurence of abdominal pain, mood shifts, migraines, endometriosis, fibroids, and anemia—the last of which, they point out, is “one of the most serious health problems in the world.”

Most serious of all is the greatly increased risk of some cancers. Cancer, after all, occurs because as cells divide and reproduce they sometimes make mistakes that cripple the cells’ defenses against runaway growth. That’s one of the reasons that our risk of cancer generally increases as we age: our cells have more time to make mistakes. But this also means that any change promoting cell division has the potential to increase cancer risk, and ovulation appears to be one of those changes. Whenever a woman ovulates, an egg literally bursts through the walls of her ovaries. To heal that puncture, the cells of the ovary wall have to divide and reproduce. Every time a woman gets pregnant and bears a child, her lifetime risk of ovarian cancer drops 10 percent. Why? Possibly because, between nine months of pregnancy and the suppression of ovulation associated with breast-feeding, she stops ovulating for twelve months—and saves her ovarian walls from twelve bouts of cell division. The argument is similar for endometrial cancer. When a woman is menstruating, the estrogen that flows through her uterus stimulates the growth of the uterine lining, causing a flurry of potentially dangerous cell division. Women who do not menstruate frequently spare the endometrium that risk. Ovarian and endometrial cancer are characteristically modern diseases, consequences, in part, of a century in which women have come to menstruate four hundred times in a lifetime.

In this sense, the Pill really does have a natural effect. By blocking the release of new eggs, the progestin in oral contraceptives reduces the rounds of ovarian cell division. Progestin also counters the surges of estrogen in the endometrium, restraining cell division there. A woman who takes the Pill for ten years cuts her ovarian-cancer risk by around 70 percent and her endometrial-cancer risk by around 60 percent. But here natural means something different from what Rock meant. He assumed that the Pill was natural because it was an unobtrusive variant of the body’s own processes. In fact, as more recent research suggests, the Pill is really only natural in so far as it’s radical—rescuing the ovaries and endometrium from modernity. That Rock insisted on a twenty-eight-day cycle for his pill is evidence of just how deep his misunderstanding was: the real promise of the Pill was not that it could preserve the menstrual rhythms of the twentieth century but that it could disrupt them.

Today, a growing movement of reproductive specialists has begun to campaign loudly against the standard twenty-eight-day pill regimen. The drug company Organon has come out with a new oral contraceptive, called Mircette, that cuts the seven-day placebo interval to two days. Patricia Sulak, a medical researcher at Texas A &M University, has shown that most women can probably stay on the Pill, straight through, for six to twelve weeks before they experience breakthrough bleeding or spotting. More recently, Sulak has documented precisely what the cost of the Pill’s monthly “off” week is. In a paper in the February issue of the journal Obstetrics and Gynecology, she and her colleagues documented something that will come as no surprise to most women on the Pill: during the placebo week, the number of users experiencing pelvic pain, bloating, and swelling more than triples, breast tenderness more than doubles, and headaches increase by almost 50 percent. In other words, some women on the Pill continue to experience the kinds of side effects associated with normal menstruation. Sulak’s paper is a short, dry, academic work, of the sort intended for a narrow professional audience. But it is impossible to read it without being struck by the consequences of John Rock’s desire to please his Church. In the past forty years,