The Ovary of Eve: Egg and Sperm and Preformation.
The history of preformation begins one evening in the middle of the seventeenth century, with an after-dinner party trick. The scene includes a group of European intellectuals, a laconic Dutch naturalist named Jan Swammerdam and a silkworm. The guests inspect the silkworm, deem it ordinary enough and return it to Swammerdam, who, with a dramatic flourish, peels away its skin to reveal the fully formed moth inside. The audience is, appropriately enough, astonished. Apparently, even theories of genesis have their genesis myths.
These were heady days for Western science. The seventeenth century witnessed the invention of the telescope and the microscope, gave birth to anatomy as a discrete branch of medicine and saw the universe expand vertiginously. By the century's end, the nutritious properties of oxygen had been identified, Jupiter had four moons and decimal fractions were in regular use. But these discoveries were overshadowed by a pressing desire to untangle the mysteries of reproduction. And on this subject, as Clara Pinto-Correia relates with much wit and humor, the Scientific Revolution spawned just as much confusion as insight. Female ovaries were not firmly established until 1672, male sperm not until almost a decade later. And even then, precisely how and what each of the sexes contributed to reproduction remained a hotly contested, morally vexed question preoccupying at one time or another most of the leading lights of Europe.
Swammerdam was a committed ovist who deduced from his work on silkworms and other insects that humans existed fully formed, albeit in miniature, inside maternal ova. Leibniz, on the other hand, was a spermist. He postulated that the squirming, long-tailed "animalcules" detected in semen corresponded to actual human souls. Both were preformationists, who believed that "all living things existed preformed inside their forebears in the manner of the Russian doll, put there by God at the beginning of Creation."
The advantages of such a theory over its main rival, the alarmingly ex nihilo epigenetic model, were several. In addition to its breathtaking simplicity, writes Pinto-Correia, preformationism offered an implicit rationale for the European caste system (kings are born from kings, peasants from peasants). More important, preformationism dovetailed neatly with Christian doctrine: All men were literally brothers, as Jesus taught, and because the entire human race had lain encased but unborn inside Eve (or Adam, depending on your preference), all were complicit in the original sin.
This last insight was undoubtedly a relief to the preformationists. For looming over most of seventeenth-century Europe was the specter of an omnipotent God. In His most popular incarnation, Cartesian philosophy, God was understood as the ultimate mechanic, a master craftsman whose hand was behind literally every event in the organic and inorganic world. Leibniz went so far as to speculate that individual thoughts, as well as beings, were preprogrammed by God at Creation. Another preformationist, an eminent French ovist, found the notion of Descartes's divinely ordered world so exhilarating that he reported experiencing bouts of cardiac arrhythmia just reading about it. "God," he enthused, "is a geometer."
Pinto-Correia, a Portuguese novelist and professor of developmental biology in Lisbon, makes the most of this engaging material. She delights in the early moderns' befuddled gropings toward knowledge and patiently pursues them down wrong turns and dead ends, all the while cheering their doggedness and ingenuity. In order to explore the role of semen in reproduction, for example, the Italian naturalist Lazzaro Spallanzani outfitted dozens of male frogs in tight, waxed-taffeta pants and allowed them to mate. Despite glaring evidence to the contrary (none of the eggs produced during these unions ever developed), Spallanzani remained a confident ovist, declaring that "the fetus exists in this species before the male performs the office of fecundation." Semen, he concluded, provided the critical but ancillary service of stimulating fetal growth. He went on to experiment with other potential growth stimulators, including vinegar, lemons and spirits of wine diluted in water and urine, but found none to rival the sure-fire potency of male sperm.
Ironically, Spallanzani's ovist convictions are now all but forgotten: Today, he is remembered as the scientist who first proved that semen was indispensable to reproduction. Which brings us to Pinto-Correia's larger argument. More than just a good story, The Ovary of Eve is an object lesson about the history of science: Don't trust it. The standard histories of embryology, writes Pinto-Correia, dismiss preformation with a derisive nod, a claim Stephen Jay Gould corroborates in a glowing foreword. "Preformationism," Gould says he learned in school, "was a nonsensical doctrine espoused by men who could not bear to give up the dream of a static world order ruled by an omnipotent God--and who therefore could not admit the plain evidence of their senses when watching the development of the chick in the egg."
Even worse, laments Pinto-Correia, modern writers on preformation have been guilty of wholesale fabrication. In one standard modern text, for example, a spermist is quoted at length on the subject of monsters. The passage sounds authentic; in theory, the spermists were well poised to explain monstrosity in humans--which in the seventeenth century included hermaphroditism, Siamese twins and lameness. Given that each sperm cell (animalcule or, popularly, "homunculus") was a potential being, and that male semen contained numerous animalcules, the obvious explanation was that some animalcules would suffer injuries in the battle for access to the egg. Hence, monstrosities might be observed in the offspring. But the passage in question turns out to be apocryphal. Although early modern medical authors devoted considerable ink to the problem, the spermists never bothered to mention monsters at all. Had they done so, Pinto-Correia speculates, spermism, might have remained a viable theory longer. (What probably did it in was what she calls the wasted seed problem: Why would God have created so many potential humans only to have, at most, a single one survive each ejaculation? God, wasteful? Impossible!)
Of course, there is no getting around the fact that the preformationists were wrong--or mostly. By the time the first installment of Tristram Shandy appeared in 1759, preformation was already a joke, serving to establish Laurence Sterne's narrator as a kvetching nebbish whose troubles began in the womb: "The Homunculus, Sir, in however low and ludicrous a light he may appear, in this age of levity, to the eye of folly or prejudice;--to the eye of reason in scientific research, he stands confessed--a Being guarded and circumscribed by rights."
But Pinto-Correia will have none of this. The ovists and the spermists, she insists, were on to something important. After all, preformation does play a role in reproduction; what is preformed is not the fetus per se but the instructions for making a fetus, DNA. In fact, she argues, in an epilogue titled "The Fat Lady Will Not Sing," preformation lives on today in the insidious arguments of Richard Herrnstein and Charles Murray and their ilk. "These authors side with those who defend the genetic view of ontogenesis--generally conservatives who emphasize that our mental limits are established at fertilization, and that no program such as Head Start or ABC can change things substantially." On the other side are proponents of the "epigenetic view [who] emphasize the plasticity of the human brain and the fact that learning actually can cause new neuronal connections to form." Pinto-Correia says she wants to tell the story of history's losers. In doing so, she makes defeat sound more appealing than victory.
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|Article Type:||Book Review|
|Date:||Feb 23, 1998|
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