Women After All: Sex, Evolution, and the End of Male Supremacy Read Online Free PDF Page A

height. We already know that men and women overlap far too much in these qualities for any of them—or, for that matter, most others—to be decisive or even close to it. No behavioral question would be like the vagina-or-penis question. But the difference could still matter.
    It’s very instructive to look at people who are really in the middle, and who are that way for biological reasons. Among other things, we soon find out that the middle is not really a linear continuum like the waist of the tube but is more like some exotic glass sculpture—small but beautiful and strange.
    Barbin was probably what doctors call a pseudohermaphrodite, which does not imply dissembling. Biologically, true hermaphrodites have both working ovaries and working testes; that means they can make both eggs and sperm. This condition is exceedingly rare. More common, although also rare, is the condition of ambiguous genitalia, which can arise in various circumstances in people who are genetically male or female. For them, the vagina-or-penis question does not have a clear answer, or at least not a consistent one throughout life, even though the ovaries-or-testes question does. Such people have greatly helped the rest of us by allowing research that sheds light on how gender more typically develops. We have to hope they have gotten worthwhile insights into themselves in the bargain, although sometimes, in the past, research has worked against them.
    At this point you may be wondering why a book about being female or male is dwelling on those who are not quite either. It’s because they are the exceptions who prove the rules. They develop as they do because of departures from one of two rather typical pathways, and the scientific analysis of those accidental detours—together with the deliberate ones in countless animal experiments—teaches us a lot about how the typical pathways work. People like Barbin—all the people who don’t fit in the two big boxes—are atypical, not abnormal. They have been called experiments in nature, and in a sense they are, provided we don’t objectify them or force them to be something they are not. These are moral obligations that precede and transcend any scientific lessons they may be so generous as to teach us.
    But before we delve further into their fascinating, sometimes threatened, and often heroic lives, we must look a bit at how maleness and femaleness, evolved over eons, are re-created in each embryo, infant, and child. What are those two classic pathways, from which some of us depart? The die is not cast in the same way in all sexual animals, but we will meditate on mammals. They cast light like that of a candle on our lives, flickering at times, dim at others, always warm, with some hue of gold. We cannot ethically probe ourselves as we can animals, but studies allow inferences, up to a point, from them to us. Here is the story of sexual development that comes out of both kinds of studies.
    We humans have forty-six chromosomes, of which ( usually ) two—X and Y—are sex chromosomes. A woman’s eggs each carry one X, and a man’s sperm are about equally divided between those with an X and those with a Y. The fertilized egg becomes XX or XY, usually synonymous with female and male. Many millions of little sperm spiritedly storm the vastly larger egg, but only one gets in before the egg’s rim shuts tight. The winning swimmer loses his tail—although we might also say he’s lost his head, which breaks offinside, enveloped by the egg. But, unlike the praying mantis male (of which more later), the sperm doesn’t offer its head for nourishment; the egg’s huge independent mass takes care of that. The sperm’s head delivers genes, particles of prized variation, toward the equally gene-rich nucleus of the egg. When they fuse, the sexual destiny of the fertilized egg is set—it is either male or female. So in losing its head, the sperm gains its reproductive future.
    There is more to it than this