reasoning behind it. Anne Fausto-Sterling, of Brown University, has complained that the notion of female as default is an intellectual vestige of the male domination of developmental biology. The reason that nobody has found any of the chemical signals that activate the female blueprint, she
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argues, is that nobody has looked for them. From a man's perspective, the mechanism behind the growth of fallopian tubes simply can't hold the fascination of the recipe for a penis. Just because hormones don't appear to be responsible for female sex determination doesn't mean that nothing is responsible; other signaling systems exist and participate in fetal growth, though they're harder to find and study than a sharp and unmistakable burst of androgens.
What we can do is reformulate the principle of female first into something less simplistic and inert than the ho-hum default mode. David Crews, of the University of Texas, proposes a lovely system for discussing the sex determination of an animal: the female is the ancestral sex while the male is the derived sex. The female form came first, and eventually it gave rise to the male variant. Athena was said to have sprung from the skull of Zeus. Perhaps we might better imagine Apollo springing from the head of Hera.
What the notion of female as ancestral sex means, when stretched to its most interesting dimensions, is that males are more like females than females are like males. Males, after all, are derived from females; they have no choice but to hold in common those features those girlish features, those pink pajamas! that were modified in the making of them. But females have no such reliance on the male prototype to invent a sense of self. Self was there to begin with; we defined self. We don't need Adam's rib, we didn't use Adam's rib; our bones calcified and our pelvises hardened entirely without male assistance.
Crews arrived at his thesis through a couple of lines of reasoning. To begin with, he studies sex determination in reptiles rather than in mammals, so he sees a different system at work, from which he can extract novel principles to counter the conventional wisdom held by the warm-bloods. He has observed that the sex of a crocodile or a turtle is not dictated by an X or a Y chromosome, the SRY gene or the testes it can build. Instead, a baby reptile is sexualized by environmental elements, particularly the air or water temperature surrounding the egg while the creature is developing. All embryos begin with bisexual potential, and then, depending on whether it is mild or cold outside, they grow either ovaries or testes. (Generally, a colder temperature yields males, a warmer one yields females, and an intermediate temperature will give rise to a brood of 50 percent males and 50 percent females.)
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Importantly, neither sex is a "default" sex. A crocodile can't become a female just by not becoming a male. The pre-she must receive some kind of stimulus, pegged to temperature, that in turn sets off a physiological chain of events to build ovaries. So too to construct testes: the young reptile requires signals from the outside world to set the masculine protocol in motion. In other words, the business of sexualizing a reptile is active and multistep whatever the final outcome will be.
Reptiles are very different from mammals; nevertheless, the details of their sex determination program tempt us to question assumptions about the neutrality of the female. There may be much that we're overlooking in the embryonic establishment of sex. For example, a male fetus's testes release müllerian inhibiting factor to destroy the primitive ducts that otherwise would flower into the fallopian tubes, uterus, and vagina. Yet in addition to her müllerian ducts, a female embryo possesses until the ninth week of gestation what are called the wolffian ducts, structures that have the potential to become the seminal vesicle, the epididymides, and other elements
page_40
Page 40
argues, is that nobody has looked for them. From a man's perspective, the mechanism behind the growth of fallopian tubes simply can't hold the fascination of the recipe for a penis. Just because hormones don't appear to be responsible for female sex determination doesn't mean that nothing is responsible; other signaling systems exist and participate in fetal growth, though they're harder to find and study than a sharp and unmistakable burst of androgens.
What we can do is reformulate the principle of female first into something less simplistic and inert than the ho-hum default mode. David Crews, of the University of Texas, proposes a lovely system for discussing the sex determination of an animal: the female is the ancestral sex while the male is the derived sex. The female form came first, and eventually it gave rise to the male variant. Athena was said to have sprung from the skull of Zeus. Perhaps we might better imagine Apollo springing from the head of Hera.
What the notion of female as ancestral sex means, when stretched to its most interesting dimensions, is that males are more like females than females are like males. Males, after all, are derived from females; they have no choice but to hold in common those features those girlish features, those pink pajamas! that were modified in the making of them. But females have no such reliance on the male prototype to invent a sense of self. Self was there to begin with; we defined self. We don't need Adam's rib, we didn't use Adam's rib; our bones calcified and our pelvises hardened entirely without male assistance.
Crews arrived at his thesis through a couple of lines of reasoning. To begin with, he studies sex determination in reptiles rather than in mammals, so he sees a different system at work, from which he can extract novel principles to counter the conventional wisdom held by the warm-bloods. He has observed that the sex of a crocodile or a turtle is not dictated by an X or a Y chromosome, the SRY gene or the testes it can build. Instead, a baby reptile is sexualized by environmental elements, particularly the air or water temperature surrounding the egg while the creature is developing. All embryos begin with bisexual potential, and then, depending on whether it is mild or cold outside, they grow either ovaries or testes. (Generally, a colder temperature yields males, a warmer one yields females, and an intermediate temperature will give rise to a brood of 50 percent males and 50 percent females.)
page_41
Page 41
Importantly, neither sex is a "default" sex. A crocodile can't become a female just by not becoming a male. The pre-she must receive some kind of stimulus, pegged to temperature, that in turn sets off a physiological chain of events to build ovaries. So too to construct testes: the young reptile requires signals from the outside world to set the masculine protocol in motion. In other words, the business of sexualizing a reptile is active and multistep whatever the final outcome will be.
Reptiles are very different from mammals; nevertheless, the details of their sex determination program tempt us to question assumptions about the neutrality of the female. There may be much that we're overlooking in the embryonic establishment of sex. For example, a male fetus's testes release müllerian inhibiting factor to destroy the primitive ducts that otherwise would flower into the fallopian tubes, uterus, and vagina. Yet in addition to her müllerian ducts, a female embryo possesses until the ninth week of gestation what are called the wolffian ducts, structures that have the potential to become the seminal vesicle, the epididymides, and other elements
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