The Seeds of Life Read online

  Instead, scientists looked around them in every direction for clues to the riddles of conception and development. How could it possibly work? Baffled but determined, they ventured down the most unlikely paths. They studied insects with obsessive care, for example, in the hope that those startling transformations—a wriggling caterpillar inside its cocoon emerges as a butterfly with gossamer wings!—would throw light on the changes in infants and babies. They studied fish and frogs and dogs and deer to see what they shared in the way of anatomy and mating behavior. They tackled the narrowest of questions—How do snails, which have both male and female genitals, sort out who will do what to whom?—and the grandest of themes—Do living organisms possess a “vital force” that sparks them to life?

  Often a quest that started in one direction ended far afield, in a landing spot no one had anticipated. The search for the vital force, for instance, led to strange and dangerous experiments with electricity and lightning, and even an encounter with Dr. Frankenstein and his monster.

  In hindsight, that zigzag progress seems inevitable, for two seemingly different questions were deeply entangled. The question, Where do babies come from? proved impossible to separate from What is life? Thus, straightforward inquiries about sperm and eggs and anatomy opened up into profound riddles about the nature of living organisms. Scientists who merely wanted to know about the body’s nooks and crannies found themselves wondering what the world was made of. How could it be that the same, ordinary stuff that forms lumps of mud and murky puddles, when rearranged in the right way, can burst into crying, crawling life?

  This was, moreover, an era when science and religion wrapped around one another, so that every statement about life implied a judgment about God the Creator. With one peek through a microscope, a scientific observation could provoke a religious battle.

  The search for the solution to the sex and conception mystery would consume careers and span centuries. My focus is on the heart of the tale, from about 1650 to nearly 1900. During that time, scientists in half a dozen countries—in Holland, France, England, Germany, Italy, even the newborn United States—would pass the torch, or burn their hands and drop it. It is surprising, in hindsight, that it did not take them longer.

  THEY SET OUT, NOT WITH HESITANCY OR TREPIDATION, BUT WITH eagerness and swagger, for their peers had just won a colossal victory. In a torrent of discoveries all through the 1600s, physicists and astronomers had demonstrated that the universe was a clockwork, the stars and planets its cogs and wheels. Spirits and demons had been banished. Nature obeyed laws and equations, not caprice. Comets were not heavenly messengers. God was a mathematician.

  The seventeenth century was a tumultuous age, bubbling over with intellectual ambition. The roll call of genius went on and on. Shakespeare, Galileo, Rembrandt, Descartes, Newton were not busts on a library shelf but flesh-and-blood titans who wielded almost unfathomable powers. The secrets of the human heart and the natural world seemed destined to give way before them.

  The scientists in that starry roster shared not merely an ambition but a way of thought. From Galileo and Newton on, they believed with an unshakable faith that their mission was to study God’s creation and proclaim the glory of his craftsmanship. This they had begun to do, and when they rattled off the list of their triumphs they were making a twofold claim. First, they had done great things. They had unraveled the rainbow and harnessed the tides. Second, and just as important, they had cracked a cosmic code. They had found out how to think of the world: it was an encrypted message written by God.

  The world was not just beautiful, like a painting that moved onlookers to delight; it was a beautifully constructed riddle that contained secrets within secrets. Humankind’s highest task, these early scientists fervently believed, was to solve that riddle, the better to honor the Creator. (And why had God made matters so difficult? If he wanted trembling homage, why not arrange the stars to spell out BEHOLD in letters of fire? For the devout scientists of the 1600s, the answer was plain. God had given humankind its defining gift, a far-ranging intellect, and he meant for us to use it.)

  The book of nature was written in the language of mathematics, Newton and his contemporaries insisted, and only the mathematically literate could read it. This was an austere view. Romantic poets would later howl that the scientists’ “cold philosophy” had drained the world of its sap and energy, as if a lush Gauguin landscape had been set aside in favor of a diagram in a geometry textbook.* But despite their somber mathematical talk, the scientists of the seventeenth century tackled the world with gusto and high hopes.

  They talked of God the mathematician, but they seemed to picture him in less imposing terms. Francis Bacon, one of the pioneers of the Scientific Revolution, took this to an extreme. His God seemed less the Almighty on a celestial throne than an indulgent parent who had devised an Easter egg hunt for a pack of toddlers. God “took delight to hide his works,” wrote Bacon, “to the end to have them found out.”

  Bolstered by their successes in understanding the physical world, scientists made bold plans to continue their advance, this time moving to living creatures. If the proud heart could be understood as a pump, the rest of the body seemed sure to follow. Muscles and bones and arteries would play the roles of levers, pulleys, and pipes; food would serve for fuel; filters and springs, plumbs and bellows, would all have their natural counterparts.

  In time, the body would yield its secrets like a watch opened up on a craftsman’s bench. Humans and animals would show themselves as more wondrous versions of the ingenious mechanical figures that adorned the clock towers of Europe’s cathedrals and emerged, on the hour, to march a few proud steps and raise trumpets to their metal lips.

  The inner workings of life, the deepest mysteries of how animals move and breathe and reproduce, would be unveiled. God, who had placed the stars in the sky and carved towering mountains, had surely lavished even greater care on the details of a bird’s wing and a whale’s fin and, especially, on the human beings he had fashioned in his own image.

  Scientists pictured the living world as a straightforward target. The inanimate world, with its hurtling planets and remote, untouchable stars, seemed more forbidding, and, indeed, Newton and his peers had needed to invent a mathematical language to describe it. Even today, we think of physics, with its black holes and hidden dimensions and parallel universes, as the realm of the incomprehensible. Biology, in contrast, deals with everyday, literally down-to-earth objects like dogs and plants and snails. Scientists had conquered physics even so. Biology would fall, too. They would make quick work of it.

  They didn’t. The bold men of science raced off to take on the mystery of life and promptly face-planted. Life was messy, it turned out almost at once, fragile and unpredictable and maddeningly coy about its secrets. A cannonball in flight plainly has no desire to go this way rather than that. Why shouldn’t a few simple laws suffice to describe its motion? But consider the gulf between a chunk of metal and a sunflower craning toward the light, or a dog tugging on its leash, or a human being. On the one side, mere matter. On the other, breathing, pulsing life. How could the same sort of laws account for both?

  Planets were easy; plants were hard. And sex and reproduction proved hardest of all. For nearly three hundred years, from about 1600 until nearly 1900, the question of where babies came from defeated one thinker after another. The vanquished lay in heaps, like soldiers on a battlefield. Late in the 1700s one scientist took the trouble to compile a list of failed theories. Scanning the centuries, he tallied “262 groundless hypotheses.” (“And nothing is more certain,” one eminent biologist remarked at once, “than that his own system is the 263rd.”)

  TWO

  HIDDEN IN DEEP NIGHT

  WE KNOW HOW THE SEX-AND-BABIES STORY TURNED OUT. THAT can make us smug—how foolish of our forebears to have lived so long ago—but it shouldn’t. To understand the plight of our predecessors, think of modern-day scientists as they wrestle with their own grand mysteries.
The hardest problem in science today—so difficult that scientists refer to it simply as “the Hard Problem,” as if there were no other—is to explain perhaps the simplest fact in the world. Why is it that it feels like something to be us? Why is it that a robot, even one that can find its way around the room and beep and blink and play chess, is simply a lifeless collection of parts, whereas we humans swim in a sea of smells and sights and memories? What, in short, is consciousness?

  If every object in the world is just a collection of atoms lumped together, how is it that some lumps just sit there but the three-pound lump that is our brain conjures up a world? How can mere stuff do that? In the words of the poet and essayist Diane Ackerman, “How do you begin with hydrogen and end up with prom dresses, jealousy, chamber music?”

  Today the deepest thinkers in the world can only stammer in response. One day, the answer may be so obvious that nobody will understand how there could ever have been any confusion. In the future, nine-year-olds may read books called Where Ideas Come From.

  In centuries past, the riddle of life seemed every bit as intractable as the riddle of consciousness does today. We understand perfectly well that brain gives rise to mind; the problem is that we cannot sort out just what that means. The scientists who made the modern world understood that certain bits of matter were alive and others weren’t; the problem was that they couldn’t sort out how that could be.

  We cannot grasp how the brain, a lump of meat locked inside a dark, bone-framed cave, can create a light-soaked world. They could not grasp how a few inert odds and ends could take the shape of a leaping tiger with daggers for teeth. To try to make headway by focusing on what seemed a narrower question, Where do babies come from?, turned out in fact to make matters even harder. Tackling the riddle of life was challenge enough; explaining new life was harder still. Within a woman’s womb a microscopic bit of tissue grows into a baby. But how did it get there? It couldn’t appear out of nothing. Where did it come from in the first place, and then how did it grow?

  MOST CONFUSING OF ALL, TO THE MALE SCIENTISTS CONTEMPLATING these riddles, was sorting out the woman’s role in this story. Plainly she carried the baby and delivered it, but what did she contribute to the making of it? The male produced semen. What did the woman do? In the twentieth century Freud would famously ask, “What does woman want?” In the seventeenth century the question was, “What are women for?”

  The simplest answer, a favorite of male thinkers since ancient times, was that woman was the field where a man planted his seed. That view was always presented as if it were the merest common sense. Aeschylus had spelled it out four centuries before Christ.

  The woman you call the mother of the child

  Is not the parent, just a nurse to the seed,

  the new-sown seed that grow and swells inside her.

  The man is the source of life—the one who mounts.

  She, like a stranger for a stranger, keeps

  the shoot alive unless god hurts the roots.

  In England twenty centuries later, many still clung to the same view. The king’s royal physician put it briskly, in a book on anatomy published in 1618: “The woman hath a womb ordained by nature as a field or seed-plot to receive and cherish the seed.” But confront those learned authorities with everyday observations, and their certainty vanished. If the mother is merely a field where the infant grows, why do children so often look like their mother? That hit close to home. Maybe women did shape their babies in some way? On the one hand, that seemed unlikely, given women’s second-class status. On the other, it seemed indisputable, for how else to explain family resemblances. What was going on?

  FROM A DISTANCE, SEX LOOKS SIMPLE ENOUGH, A BIT OF HUFFING and puffing and some rudimentary choreography. But the key scenes in the drama—conception and then development over the course of nine months—take place deep inside the body, hidden from view. Nature, lamented William Harvey, concealed these biological secrets “in obscurity and deep night.”

  And even if you could see, you could not expect much from a search where you were not certain what you were looking for. No one knew, for instance, if women had eggs. Scientists split into feuding camps—one insisted that women, like birds, produced eggs; their rivals shouted that women, like men, produced a sort of semen.

  Opinions abounded, but facts were rare and elusive. Egg and sperm, we now know, were not merely hidden but tiny. The human egg, though it is the largest cell in the body, is only the size of the period at the end of this sentence. Sperm cells are the smallest in the body, far too little to see with the naked eye. (An egg outweighs the sperm cell that fertilizes it by a million to one, the difference between a Thanksgiving turkey and a housefly.) The mystery of human development was never going to be as simple to investigate as the path of a falling rock.

  Merely sorting out the basic facts of human anatomy was hard, grim work. To peer inside the living body was next to impossible.* Dead bodies were the only alternative but a poor fallback when your goal was understanding life. Dissections were carried out in the cold (to keep the corpse from decomposing) while the anatomist poked his knife into dark, wet crevices. Fascination and horror twined around one another. “You might be stopped by your disgust,” Leonardo da Vinci wrote, no matter how strong your curiosity, “and if that did not hinder you, then perhaps by the fear of spending the night hours in the company of those dead bodies, quartered and flayed and terrifying to behold.”

  High as the practical hurdles were, others stood higher still. All questions that had to do with birth and babies were charged and not simply because they had to do with that most fraught of all subjects, sex. In a God-drenched age like the 1600s, a venture into science was a dive into religion. Those were roiling waters. Everyone believed that God had fashioned the world and all its inhabitants, as the Bible detailed. God alone had the power to create life. How could one speak of the exalted work of creation and, in the same breath, of ordinary men and women clutching one another and gasping in the dark?

  The whole scientific enterprise, with its talk of humans as sophisticated machines, was dangerous in two different ways at once. First, it threatened to push God to one side. That was blasphemy, and no more hideous charge could have been imagined. Second, and almost as bad, the scientific way of thinking seemed to drain purpose and meaning from the world. An assemblage of lifeless parts was not responsible for its actions. If humans were machines, a husband might strangle his wife and bear no more blame than a runaway carriage that plowed into a crowd.

  In a different age, those contrasting approaches to the world would have pitted scientists against religious believers. That conflict would have been clear-cut. But in this case the scientists and the believers were the same people. The battle lines ran not between opposing factions but through the minds of individual men. Brilliant, ambitious, confused, conflicted, these reluctant revolutionaries sought desperately to find a way to fit their new discoveries with their old beliefs.

  When it came to sex, they found themselves more confused than ever. They could not imagine, first of all, why God had devised so bizarre a system for preserving the human species. What could be less dignified? “Who would have solicited and embraced such a filthy thing as sexual intercourse?” demanded France’s royal physician, in 1600. “With what countenance would man, that divine animal full of reason and wisdom, have handled the obscene parts of women, befouled with such great quantities of muck and accordingly relegated to the lowest part of the body, the body’s bilge as it were?”

  And, the learned physician went on, women didn’t fare so well out of this sex business, either. “What woman would have rushed into a man’s embrace unless her genital parts had been endowed with an itch for pleasure past belief? The nine months of gestation are laborious; the delivery of the fetus is beset with dreadfully excruciating pains and often fatal; the rearing of the delivered fetus is full of anxiety.”*

  In the end, though, it was God who had ordained this odd system, just as he had
created the sky and the seas. No doubt he had his reasons.

  THE GREAT INVESTIGATION STARTED WITH A FEW FACTS THAT EVERYONE could agree on, but these were isolated landmarks in a vast and empty landscape. Nearly every culture had figured out early on that it takes two to tango. Of the two partners, males presented fewer mysteries than females because they kept their working parts on the outside, on conspicuous display, in the mode of the Pompidou Center.

  The role of the penis seemed plain enough, though just how it managed its furlings and unfurlings was not resolved. Biologists and physicians all agreed that the testicles had something to do with sex and babies, too, but it was by no means clear what they did. (Aristotle contended that they were merely oddly packaged counterweights, akin to those that women hung from the threads in their looms to keep them from tangling. In the case of males, Aristotle explained, the weights served to keep the seminal vessels unsnarled.)

  Semen, as the only impossible-to-miss product of sex, was plainly a crucial part of the puzzle, but it remained utterly mysterious. The standard notion among scientists (virtually all of them male, in these early days) was that semen was a magical, almost divine concoction. Precisely what form that magic took was in dispute: Did semen exert its influence without physical contact, as sunlight nurtured plants, or did it serve as the key ingredient in a divinely ordained recipe, as a kind of baby batter?

  Women’s anatomy was poorly understood. The structure of the vagina was known, and so was that of the uterus. After that, almost any question would have elicited confusion or dispute. What were the Fallopian tubes for? What about the ovaries, which did not even have a name of their own and were referred to as “female testicles”? What was menstruation? Beyond agreement across cultures and across millennia that it served as proof of women’s low status (menstrual blood soured wine, withered grass, and drove bees from their hives, according to Pliny, the acclaimed Roman author of Natural History), no one knew.