II
IT IS SOMETIMES said there are more genetic differences between men and women than there are between humans and chimpanzees. Well, perhaps. It all depends on how you measure genetic differences. But the statement is in any case clearly meaningless in any practical sense. A chimpanzee and a human may have as much as 98.8 percent of genes in common (depending on how they are measured), but that doesn’t mean they are just 1.2 percent different as beings. Chimpanzees cannot hold a conversation, cook dinner, or outwit a human four-year-old. Clearly, it is a question of not what genes you have but how they are expressed—how they are put to use.
That said, men and women unquestionably are very unalike in many important ways. Women (and we are talking here about healthy, fit women) carry about 50 percent more fat on their frames than fit, healthy men. This not only makes the woman more agreeably soft and shapely to suitors but also gives her reserves of fat she can call upon for milk production during times of hardship. Women’s bones wear out sooner, particularly after menopause, so they suffer more breaks in later life. Women get Alzheimer’s twice as often (partly because they also live longer) and experience higher rates of autoimmune diseases. They metabolize alcohol differently, which means they get intoxicated more easily and succumb to alcohol-related diseases like cirrhosis faster than men do.
Women even tend to carry bags differently than men do. It is thought that their wider hips necessitate a less perpendicular carrying angle for their forearm so that their swinging arms aren’t constantly banging against their legs. That’s why women generally carry bags with their palms facing forward (allowing their arms to be slightly splayed) while men carry them with palms facing back. Far more significantly, women and men have heart attacks in quite different ways. A woman suffering a heart attack is more likely to experience abdominal pain and nausea than a man, which makes it more probable that it will be misdiagnosed. In a thousand ways large and small, they are quite different beings.
Men have their own differences. They get Parkinson’s disease more often and commit suicide more, even though they suffer less from clinical depression. They are more vulnerable to infection than females (and not just humans but across nearly all species). That may indicate some hormonal or chromosomal difference that hasn’t yet been determined, or it may simply be that males on the whole lead riskier, more infection-prone lives. Men are also more likely to die from their infections and from physical injury, though again whether that is because we are hormonally compromised or just too proud and foolish to seek medical attention promptly (or both) is an unanswerable question.
All this is important because until recently drug trials very often excluded women, largely because it was feared their menstrual cycles could skew results. As Judith Mank of University College London told the BBC program Inside Science in 2017, “People had been assuming that women are just 20 percent smaller than men, but otherwise are much the same.” We now know that there is much more to it than that. In 2007, the journal Pain reviewed all of its published findings over the previous decade and found that almost 80 percent had come from male-only tests. A similar gender bias, based on hundreds of clinical studies, was reported for cancer trials in the journal Cancer in 2009. Such findings are seriously consequential because women and men can respond to drugs in very different ways—ways often overlooked by clinical trials. The drug phenylpropanolamine was commonly used in over-the-counter medications for colds and coughs for years until it was discovered that it appreciably increased the risk of hemorrhagic stroke in women but not in men. Similarly, an antihistamine called Hismanal and an appetite suppressant called Pondimin were withdrawn after they were shown to pose serious risks to women, but only after the first had been on the market for eleven years and the second for twenty-four. Ambien, a popular sleep medication in America, had its recommended dosage for women cut in half in 2013 when it was found that a high proportion of female users were suffering impaired performance if they tried to drive the next morning. Men did not suffer in anything like the same way.
Women are anatomically different in one other very significant way: they are the sacred keepers of human mitochondria—the vital little powerhouses of our cells. Sperm pass on none of their mitochondria during conception, so all mitochondrial information is transferred from generation to generation through mothers alone. Such a system means that there will be many extinctions along the way. A woman endows all her children with her mitochondria, but only her daughters have the mechanism to pass it onward to future generations. So if a woman has only sons or no children at all—and that happens quite often, of course—her personal mitochondrial line will die with her. All her descendants will still have mitochondria, but it will come from other mothers on other genetic lines. In consequence, the human mitochondrial pool shrinks a little with every generation because of these localized extinctions. Over time, the mitochondrial pool for humans has shrunk so much that, almost unbelievably but rather wonderfully, we are all now descended from a single mitochondrial ancestor—a woman who lived in Africa about 200,000 years ago. You might have heard her referred to as Mitochondrial Eve. She is, in a sense, mother of us all.
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For most of recorded history, we have known shockingly little about women and how they are put together. As Mary Roach notes in her delightfully irreverent book Bonk, “Vaginal secretions [were] the only bodily fluid about which virtually nothing was known” despite their importance to conception and a woman’s general sense of well-being.
Matters specific to women—menstruation above all—were almost totally a mystery to medical science. Menopause, clearly another milestone event in a woman’s life, didn’t attract formal notice until 1858, when the word is first recorded in English, in the Virginia Medical Journal. Abdominal examinations were conducted rarely, vaginal examinations almost never, and any investigations below the neck usually involved the doctor feeling blindly under the bedclothes while gazing fixedly at the ceiling. Many doctors kept dummies so that a woman could point to the affected part without having to reveal or even mention it by name. When René Laënnec invented the stethoscope in 1816 in Paris, the greatest benefit wasn’t that it improved sound transmission (an ear to the chest was actually about as good) but that it allowed a physician to check a woman’s heart and other inner workings without directly touching her flesh.
Even now, there is a huge amount concerning female anatomy about which we are uncertain. Consider the G spot. It is named for Ernst Gräfenberg, a German gynecologist and scientist who fled Nazi Germany for America and there developed the intrauterine contraceptive device, which was originally called the Gräfenberg ring. In 1944, he wrote an article for the Western Journal of Surgery, Obstetrics and Gynecology in which he identified an erogenous spot on the wall of the vagina. The Western Journal of Surgery, Obstetrics and Gynecology did not normally attract a great deal of attention, but this article got passed around. Thanks to it, the newly identified erogenous location became known as the Gräfenberg spot, subsequently shortened to G spot. But whether or not women actually possess a G spot is a matter of continuing, and sometimes heated, debate. Imagine the amount of research funding that would follow if someone were to suggest that males have an erogenous spot that they have not been fully utilizing. In 2001, the American Journal of Obstetrics and Gynecology declared the G spot a “modern gynecologic myth,” but other studies have shown that a majority of women, in America at least, believe they have one.