Woman: An Intimate Geography (21 page)

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Authors: Natalie Angier

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dometrium; if a placenta forms, they will deliver it blood. When the endometrium dies, it takes with it the vascularization, the tips of the spiral arteries, the fingers of blood. As it happens, the vascular architecture of the uterus in many other mammals is less ornate, and those mammals exhibit little or no menstrual bleeding. The species that have spiral arteries humans and certain other primates also shed the most blood. It's a structural thing, Strassmann says, a matter of plumbing rather than defense. We could resorb and recycle the tissue and the blood; that would certainly be a parsimonious approach, a nod to Miser Nature. And we do resorb, to a point. But the human uterus is quite large compared to the human body, and we simply can't take it all back. Nor can other primates with wombs large relative to their body size, and those, as a rule, are our sisters in blood.
What, then, can we conclude about this extraordinary and pedestrian aspect of womanness, the monthly flux, the forty quarts of blood and fluid that we discard in a lifetime of menses? Whom should we believe about why we bleed: Profet, Strassmann, the gynecologists, you perhaps, if you have a theory of your own? In fact, we may not need to choose. If there is one lesson I've learned in observing biology, it is that nothing in a living organism is just one thing. Nature's economy lies above all in making maximum use of what is, a process that we may call pleoaptation, the adaptation of an organ or system to multiple uses. The liver, for example, the largest gland in the body, performs more than five hundred tasks, including processing glucose, protein, fats, and other compounds the body needs, generating the hemoglobin that is the soul of a red blood cell, and detoxifying the poisons we consume when we drink wine or eat those fibrous packets of natural toxins called vegetables. Can we say that the liver is really for one thing and only incidentally for the others? No. Regardless of what problem the prototype liver arose to address and the organ first appeared, in a primitive form, hundreds of millions of years ago in invertebrates it has since taken on many other essential roles, and has been selected for just such pan-utility ever since. By the same token, we sweat to keep from overheating, but we also sweat when we are anxious or eat spicy food, to help rid the body of noxious chemicals such as stress hormones and curry. And then there is that pair of modified sweat glands known as

 

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breasts, which exude an unusual form of sweat of particular interest to newborns.
Menstruation, then, may be a pleoaptation. It is energy-efficient, and it is protective. We can make of these qualities what we will, so let us celebrate them. One is for the greater good, the other for ourselves. Consider the bleeding, and the theory that it is a byproduct of our hypervascularized uterus. Why all the vessels, those arterial Slinkies? The spiral arteries support a large, Draculean placenta. The placenta must be large and rich to support the growth of the fetal brain. Brain tissue is insatiable. Pound for pound, it is ten times more expensive to maintain than any other tissue of the body. During the last three months of pregnancy, the growth of the fetal brain is so explosive that stoking it demands nearly three quarters of all the energy entering the baby through the umbilical cord. No wonder the cord is so fat, so much like a long sausage, and no wonder the expulsion of the meaty placenta after the birth of the baby is considered an event in itself, worthy of being classified as the third stage of labor (the first being the dilation of the cervix, the second the delivery of the infant). The baby's brain must eat, and it eats blood.
One answer to the question of why we bleed, then, may simply be because we humans are so bloody smart.
Ah, but this articulation alone smacks too much of the martyr's plaint: we bleed so that our sons may think. And our daughters too, but they at least will be paying the species' price with their own deciduas soon enough. Camille Paglia claims that by menstruating, "women [bear] the symbolic burden of man's imperfections, his grounding in nature." We are saying something different: that women shoulder the burden of the human brain, the organ that allows at least the illusion of free will, transcendence, the
escape
from nature's grindstone. Nonetheless, what a bore to have the burden of cultivating human consciousness be so one-sided.
Enter the antipathogen aspect of menses, the ability of bloodshed to purify and rout, the womb as warrior. This is a selfish, active, and erotic explanation for menses, an acknowledgment that we are carnal beings whose sexual activity far exceeds any reproductive needs. In our defensive bleeding, we are not helping our offspring or our mates or the whole damned race; we are helping ourselves.

 

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Let us help others too. When your daughter or niece or younger sister runs to you and crows, "It's here!" take her out for a bowl of ice cream or a piece of chocolate cake, and raise a glass of milk to the new life that begins with blood.

 

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6
Mass Hysteria: Losing the Uterus
If the ultimate purpose of menstruation remains unclear, well, mystery loves company, and two thousand years after Hippocrates dressed the uterus in suckers and horns, it still resists summation. Metaphorically, it continues to wander, and we must continue to chase it. Only in the past few years, for example, have researchers learned of the endometrium's productive capabilities. Our muscular, upside-down little pears, it seems, are pharmaceutical laboratories of admirable industry, giving the lie to yet another medical paradigm. For years the uterus was viewed as a mere recipient of biochemical information, the target of endocrine activity generated elsewhere in the body. It was not thought to manufacture essential chemicals or signaling molecules on its own. The ovaries told the endometrial lining to thicken, and
mirabile dictu
, it thickened. A fertilized egg told it to give up some of its blood, and blood donor it became.
More recently, though, the uterus has emerged as a maker as well as a taker. Yes, it responds to steroid hormones from the ovaries and other organs, but it also expresses hormones and releases them into the global marketplace of the body. It makes proteins, sugars, and fats, all of which figure in Strassmann's analysis of the metabolic costs of menstruation. It makes prostaglandins, chemicals that exert an array of effects on the body. Most notably, prostaglandins prompt the smooth muscle tissue of the body to contract. Smooth muscle means unstriated muscle. The muscles that attach to your skeleton, like those of the arms, legs, face, and vagina, are striated, built of bundles of tough fibers; striated muscles can be flexed voluntarily. The muscles surrounding your internal organs are smooth. They look smooth to visual and microscopic inspec-

 

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tion and also are smooth in the sense of ''smooth operator" they're out of your control. (The heart muscle is an exception to this two-party system; it is a striated muscle that happily beats whether you tell it to or not.) The muscle of your uterus is the epitome of smooth muscle. Unless you are a yogi who can tap into supraconscious states of body and will, you cannot make your uterus contract on command but prostaglandins can. And the uterine production of prostaglandins is in part an autocrine one, that is, acting on itself and causing the mother organ to compress. The uterus makes prostaglandins to help expel decidua during menstruation, causing the contractions we experience as our old companions menstrual cramps. It makes prostaglandins during labor to help widen the cervix and push out the baby. But the uterine prostaglandins are not so provincial, and they will animate other smooth muscle tissue as well. They very likely affect the walls of your blood vessels, improving vascular tone and perhaps preventing the stiffening of the vessels that can lead to high blood pressure and heart disease.
There is more to the womb's inventory. The organ fabricates drugs that in other contexts would be illegal. It synthesizes and secretes beta-endorphins and dynorphins, two of the body's natural opiates and chemical cousins to morphine and heroin. It makes anandamide, a molecule almost identical to the active ingredient in marijuana. Until recently, these compounds were thought to be the exclusive property of the central nervous system the brain and spinal cord. After all, we learned about natural opiates and natural marijuana by studying the impact of their plant-borne equivalents on the brain. The brain was thought to make these compounds endogenously because the brain sometimes needed them, perhaps to ease pain, perhaps to facilitate pleasure. Now it seems that the brain is an anodynic also-ran. The uterus produces at least as much opiate material as neural tissue does, and it makes ten times more of the cannabis equivalent than any other organ of the body does. We do not yet know why, though it's easy to spin theories. A pregnant woman will tell you in no uncertain terms of what use a steady stream of natural painkillers might be. If the womb is going to make such a spectacle of itself, the least it can do is to offer a source of comfort as it grows. Perhaps it makes opiates and cannabinoids so that it doesn't hurt too much in distention. Or perhaps the

 

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fetus is the intended beneficiary of the womb's pharmacopoeia. It is a tight squeeze in there, after all.
But painkilling is surely not the whole story, if indeed it is part of the story at all. Very likely the uterine opiates and their precursors influence the structure and performance of other body systems, including the blood vessels that permeate the uterus. The anandamides, for their part, seem to be part of the mechanism that controls cross-talk between the endometrium and the embryo that would implant in it. In this scenario, the uterus produces the marijuana-like compound in an optimal dose at just the spot where attachment should take place. The embryo has on its surface receptors for that marijuana-like molecule. When it is several days old and ready to fasten itself to the uterus, it moves toward the designated site of attachment and becomes literally hooked, embryo receptors clasping cannabinoid proteins. Now the embryo can invade the wall of the uterus. Now it can start forming the placenta that will feed it for nine months. The blastocyst is as yet brainless. There is nothing here of psychoactivity; the use of anandamide as a signaling molecule is purely coincidental, a molecular pleoaptation. Yet it is a pretty coincidence. A cannabinoid offers to the embryo in hard currency what it gives the recreational mystic only in fantasy: the path to enlightenment, to eyes that see and a mind to make of those sights what it will.
In truth, we know remarkably little about the purpose of the various opiates, chemicals, hormones, and hormone precursors that the uterus secretes with such vigor. We don't know how important the output is to our overall health and well-being beyond considerations of reproduction, nor do we know whether the various secretory skills continue past menopause. When the endometrium ceases to wax and wane, does the secretory program of the uterus likewise lapse into quiescence? Some experts say yes, some say no, all should probably settle with "don't know." We should be humbled by the fact that scientists discovered the very dramatic concentrations of anandamide in the uterus as recently as the late 1990s. And that humbleness should in turn enhance our vigilance against removing the uterus in all but the most extreme circumstances.
The hysterectomy is one of the most ancient surgeries, the first on record having been performed in Rome around the year
A.D.
100 by the

 

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Greek physician Archigenes. Today it is routine, like a root canal or the removal of cataracts. Every year at least 560,000 women in the United States are hysterectomized. That figure is so big it hurts to think about it. What it works out to is that every minute of every hour of every day, a woman has her uterus scooped out, sometimes abdominally, as Hope Phillips's was, sometimes through a tube inserted into the vagina or into a small slit in the stomach. Nor are the figures changing much from one year to the next, despite all the fury that has surrounded the practice for the past two or three decades. The rate did dip in the early eighties, possibly as a result of the rise of an activist women's health movement, but it has stayed pretty constant ever since. Some parts of the country are more hyster-happy than others. The incidence of the surgery is highest in the South and higher in rural areas than in major cities. However the geographical particulars shake out, the United States ranks as a world leader in hysterectomies, surpassing by anywhere from two-to six-fold the rates seen in Europe and the developing world. Only Australia and Japan manage to keep pace with us in womb-shucking.
The reasons, or "indications," for a hysterectomy are many. Only about 10 percent of the surgeries are performed to treat life-threatening illnesses such as cervical or uterine cancer. The rest are for so-called benign conditions, though they may feel malign to the women who suffer them. The commonest prompt is fibroids, Hope's hell; they account for almost 40 percent of all hysterectomies. Other typical reasons include endometriosis, when stray bits of endometrial tissue break away from the inside of the uterus and grow where they shouldn't, like on the outside of the uterus or around the fallopian tubes; unexplained heavy bleeding; unexplained pelvic pain, and the dipping down, or prolapse, of the uterus into the vaginal canal. The forties are dangerous years for the uterus. That's when a woman's menstrual cycles start becoming irregular and often heavier than before, when fibroids can start growing with the avidity of a fetus, and when a woman is old enough to think, To hell with it, I'm done with having or avoiding having children, maybe I don't need this bloody pouch after all. A woman who makes it to menopause with her uterus in situ has a good chance of keeping it till death does its part.
The story of hysterectomies is a huge one; with the numbers we're talking about, it has to be. Many books have been written on the

 

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