The Seeds of Life
Page 23
Volta made a formidable rival. Weighed down with scientific prizes and honors, he was combative, self-assured, and in happy possession of, in his own words, “a genius for electricity.” In connections and temperament, though not in talent, Galvani was overmatched.
The clue that Volta jumped on was the twitching on a sunny day. As Volta explained—and as scientists now agree—Galvani had unknowingly created an electric current that flowed between the iron railing and the brass hooks. The presence of two different metals was the key; the frog was beside the point.
To test his theory, Volta skipped the frogs altogether and instead arranged a tall stack of alternating silver and zinc discs. In between each disc he inserted a piece of cardboard soaked in salt water. Then he wired up this metal and cardboard tower. “Volta demonstrated that an electric current flowed when the top and bottom of the pile were connected,” one modern scientist writes. “He had invented the first electric battery.” The frog was, so to speak, a red herring.
Volta had won the day, or so the world concluded. A clash that pitted biology (and Galvani) versus physics (and Volta) was not a fair fight. In 1800 biology was still struggling for respect and tainted by its links to medicine, which reeked of quackery. Physics basked in a glow cast long before by Galileo and Newton and their fellow titans. Biology was a scruffy upstart, physics a haughty ruler, and that contest was no contest.
In hindsight we can see that both Galvani and Volta had grasped part of the truth. It would take nearly two centuries for the details to emerge, but it would finally become clear that, in the body, biology and physics work in tandem. Bodies are made of cells—Galvani and his contemporaries had no idea—and each of those microscopic cells is a kind of chemically powered battery. As a result, every living creature is a sound-and-light show, with Galvani and Volta, the one-time foes, as coproducers. Every thought and sensation we experience is an electrochemical extravaganza. When Walt Whitman exclaimed, in 1855, “I sing the body electric,” he spoke truer than he knew.
GALVANI DIED AT AGE SIXTY-ONE, IN 1798, HIS BATTLE WITH VOLTA still unresolved. (The world “laughs at me,” Galvani supposedly lamented, “calling me ‘the Frog’s dancing-master,’ but I know that I have discovered one of the greatest Forces in nature.”) In London, in 1803, his nephew Giovanni Aldini prepared a demonstration that his earnest, quiet uncle would never have permitted. Aldini was a showman with a taste for controversy and the macabre. Galvani had carried out innumerable meticulous experiments on frogs. Aldini’s style ran more to zapping electricity through the body of a freshly hanged murderer, while a crowd gasped.
After Galvani’s death, Aldini took over the family business, preaching the electric gospel across Europe. His credentials were impeccable. He was a professor of experimental physics at the University of Bologna, and he had begun working with Galvani on his frog experiments, in a makeshift laboratory in Galvani’s home, as soon as he had graduated from college. Once on his own, he moved from experimenting on cold-blooded animals like frogs to warm-blooded ones, starting with birds, sheep, and oxen. Then came human corpses.
In the winter of 1802, near the Palace of Justice in Bologna, Aldini fired up an electric battery. As spectators looked on, Aldini wrote, “the first of the decapitated criminals was brought to the room I had chosen.” The men had been executed an hour before. Aldini attached wires from his battery to various points on the body, which twitched in much the way a frog did. Then he connected wires to the two ears of a severed head. The muscles of the face contorted in “the most hideous grimaces,” and the dead man’s eyes blinked open and shut.
Aldini continued on to England. He lectured on animal electricity in Oxford and London and sent electric charges coursing through corpses in the anatomy theaters of London’s leading hospitals. Dukes, doctors, and, once, the Prince of Wales looked on in fascination and horror.
Aldini pulled off his most spectacular coup in January 1803. A London man named George Foster had been convicted of murdering his wife and infant daughter. Too weak or too despondent to walk, Foster was dragged up the stairs to the gallows and then, the newspapers reported, “launched into eternity.” The body (with head intact) was cut down and rushed to the Royal College of Surgeons, where Aldini and an eager crowd waited.
Aldini connected one metal rod to the corpse’s mouth and another to an ear. Foster’s jaw quivered, and his facial muscles clenched and relaxed. He opened one eye. Aldini moved his metal contacts. Foster lifted one hand and made a fist. His legs shook and kicked. Spectators gasped that Foster had come back to life, and one man fled the room and, according to newspaper reports, promptly died of fright.
FIGURE 22.1. Giovanni Aldini attempts to animate the head of a corpse (above left) and a corpse without a head (bottom).
For nearly twenty years more, doctors would continue sending jolts of electricity through the bodies of newly executed criminals. (In Scotland, in 1818, one dead man kicked out a leg so violently that he nearly knocked over the surgeon’s assistant; the corpse’s chest rose and fell, as if he were breathing, and his fingers “moved as nimbly as those of a violinist.”Spectators vomited and fainted.)
Aldini and the others had come near an important truth—they had grasped that electricity is the force that powers living organisms, though they had not understood how that happens—but they did not inspire further generations of scientists to follow their lead with experiments of their own.
Instead, Aldini inspired Mary Shelley to create one of literature’s enduring horror stories.
June 1816, near Lake Geneva Summer has been cold and rainy, and the poet Byron and three visiting friends have found themselves trapped indoors yet again. Byron is only twenty-eight but already an international celebrity. Four years have passed since he “awoke one morning and found myself famous.” He has been called “mad, bad, and dangerous to know,” and he is working mightily to live up to the description. Caught up in a swirl of sexual scandals and chased by bill collectors, he has left England barely ahead of his pursuers. He left in style. His coach was an exact copy of Napoleon’s; he was attended by a valet, a footman, and a personal physician; his entourage included a peacock, a monkey, and a dog.
No one yet knows Percy Shelley. In 1816 the future poet is simply a strange and bookish young man who was booted out of Oxford a few years before for advocating atheism. Shelley’s lover is a brilliant young woman, Mary Godwin. Only eighteen, she has lived with Shelley since they eloped when she was sixteen. She has already given birth to two children—the first died at two weeks of age—and she is pregnant again. Standing at the group’s edge trying to get a word in is John Polidori—“poor Polidori,” Mary Godwin calls him—a much-derided doctor and aspiring writer supposedly tending to Byron’s health. Polidori attended the University of Edinburgh during the heyday of its body-stealing, grave-robbing era.
They talk deep into the night, evening after evening. All four are fascinated with the latest scientific developments, especially those having to do with electricity and life’s “vital forces.” Percy Shelley’s obsession runs deepest of all. Even in childhood, his hands had been perpetually spotted and stained with chemicals, his clothes dotted with holes where acids had splashed on him. The more dangerous an experiment, the more appealing. Growing up, Shelley enlisted his sisters as his involuntary test subjects, and one later recalled how “my heart would sink with fear at his approach.”
The sight of wires and other bits of electrical apparatus, the better to generate shocks, was especially bad news. “We were placed hand in hand round the nursery table to be electrified,” Helen Shelley recalled miserably. At Oxford, Shelley’s room overflowed with vials and beakers for his forays into chemistry, and visitors had to navigate a path between microscope, telescope, air pump, and an assortment of electrical contrivances. At age eighteen, he wrote a letter proclaiming that “man is no more than electrified clay.”
FIGURE 22.2.Drawing of the monster from the original edition of Frankenstein.
He is nearly forgotten today, but Erasmus was a prominent physician, an early advocate of evolution (and Charles’s grandfather), and a lively poet famous for his bold ideas and his good cheer. (He grew so fat from a lifetime of lavish meals that he had a semicircle cut from his dining room table to accommodate his belly.) Byron and Shelley tell how, as Mary recounts it later, Erasmus had “preserved a piece of vermicelli in a glass case, till by some extraordinary means it began to move with voluntary motion.” The poets gasp. If a strand of pasta could come to life, what else might be possible? “Perhaps a corpse would be re-animated,” Mary writes. “Galvanism had given token of such things: perhaps the component parts of a creature might be manufactured, brought together, and endued with vital warmth.” Thus was Frankenstein born.*
In hindsight, it seems that Byron and Shelley had not quite understood. Erasmus had written not of “vermicelli” but of “vorticellae,” microscopic creatures found in pond water. No matter. Mary Shelley grabbed her pen. “It was on a dreary night of November that I beheld the accomplishment of my toils.… I saw the dull yellow eye of the creature open; it breathed hard, and a convulsive motion agitated its limbs.”
TWENTY-THREE
THE NOSE OF THE SPHINX
BY THE EARLY DECADES OF THE 1800S, THE AGE OF MARY Shelley and Frankenstein, biologists found themselves stymied. Life seemed fated to remain a dark mystery. Galvani thought he had answered a crucial question—What is the source of the power that propels living creatures?—but Volta had shot him down. Back to square one.
In the meantime, the question of “vital force” remained crucial and unresolved. The blindest man could see that living creatures have some source of power that lets them carry on moving and digesting and growing. Moreover, those batteries or engines or whatever they might be work on their own, automatically, without any outsider intervening to throw a switch or turn a key. (Life would be far less mysterious if babies looked like wind-up dolls, with keys sticking out of their back, and parents dutifully wound them up each morning.) If it wasn’t electricity that provided that power, what did?
The temptation was to say, “Food.” But that was no answer, everyone saw with chagrin, because that supposed explanation led immediately to an equally baffling question, “And how does that work?” You could cram bits of food inside a doll forever, after all, and the doll would never whir into motion.
Past eras had concluded that the question was out of reach and moved on, but a scientific age demanded some sort of answer. Three centuries had passed since Michelangelo had depicted God passing a divine spark to Adam through an outstretched hand. The image was as glorious and uplifting as ever, but now it served more as an emblem of the mystery than an answer to it.
Whatever the vital force was, it was evidently in short supply. We humans see life all around us, because we cannot help putting ourselves at the center of every picture. But life is extraordinarily rare. If all the world’s a stage, it is an almost entirely empty stage in an empty auditorium. The present-day physicist Alan Lightman has tried to put numbers to that barrenness. “Only about one millionth of one billionth of one percent of the material of the visible universe,” he estimates, “exists in living form.”
The urgent task, as the nineteenth century saw it, was finding what distinguished those few precious bits. What set living organisms apart from nearly everything else? The quest to find out took two distinctly different paths. The first followed directly from the work of Spallanzani and Leeuwenhoek and their anatomist forebears. The idea was to look ever more closely at egg and sperm to try to sort out the mechanics of fertilization. To learn where life comes from, learn where babies come from. The other path took more of a bird’s-eye view. The aim here was not to sort out the anatomical details of sperm and egg but to tackle a far broader question: What does it mean to be alive?
The curator of the botany collection at the British Museum believed staunchly in this second approach. But not for him any of this foolishness involving batteries and shocks and jumping soldiers. Robert Brown focused instead on his beloved plants. In 1827, he set himself a curious mission.
Brown had spent his career staring at plants under a microscope. He would tackle the riddle of the life force as he had taken on countless challenges, by staring and thinking. Quite likely he would not see anything directly. But perhaps he could learn about his quarry by examining its effects, as a meteorologist might study the wind by looking at trees exposed on a mountainside. Brown began by taking pollen grains and sprinkling them in a drop of water. (His notion was that pollen, from the male parts of a plant, would be more active than female bits, which would no doubt sit dully and passively in place.)
To Brown’s delight, the pollen grains never settled down quietly. They jiggled, and they kept jiggling. This was surely the vital force in action. With the entire British Museum collection to draw from, Brown carried out a series of follow-up experiments. He ground up pollen grains from a variety of recently gathered plants and from plants that had been dead for a century. The result was always the same—the pollen grains kept up a perpetual dance. This was almost too good. The life force seemed to persist beyond death! Now Brown ground up the female parts of plants. Bizarrely, those grains danced, too.
Brown retreated. The life force evidently had to do with sexuality in general and not solely with maleness, as he had expected. Then came a fortunate accident. Careful though he was, Brown happened to contaminate one of his experiments. Bits of a crushed leaf—neither male nor female—fell into a water drop. Brown took a close look. The leaf particles jiggled, too!
Brown retreated further still. Inside every bit of every organism, he proposed, whether it was now living or had lived long ago, lay tiny, hidden particles steeped in “vital force.” Over the course of the next year, Brown tested this new theory thoroughly and methodically. He ground up plants and vegetables of all sorts, and then bits of animal tissue, then flecks of coal (from prehistoric plants), and specks of petrified wood. They all jiggled.
With all those confirmations of his theory in hand, Brown might have declared victory. Instead, and admirably, he devised a test that might bring everything crashing down. He ground up bits of glass, which had never been alive. They danced as energetically as specks from a green and thriving plant! Brown tried pieces of metal; they jiggled. So did fragments of rock. As a grand finale, Brown took the deadest thing he could think of—a tiny speck from the nose of the Sphinx—and dropped some crushed particles into water. They jiggled!
Brown gave up. So did everyone else. The dancing movement he had identified was named “Brownian motion,” but no one in the nineteenth century managed to make sense of it. Finally, in 1905, Albert Einstein explained what was going on.* At the time, scientists had not yet agreed on whether atoms and molecules were real, physical objects. Einstein argued that they were, and he pointed to Brownian motion as proof. Look at the way a speck of dust dances around on the surface of a glass of water, Einstein said. Its zigging and zagging tells us that it is being kicked this way and that by real but too-small-to-see particles within the water.
Einstein won the day. Back in 1828 Brown met a harsher reception. But he had, against his will, deeply undermined the theory that living objects contain an animating, intangible force that nonliving objects lack. More challenges would come, and in the same year of 1828.
CLOSE KIN TO THE THEORY OF VITAL FORCE WAS THE IDEA THAT living organisms and lifeless ones were made of different building blocks. (The term “organic chemistry”—this is the class that has tormented generations of premed students—reflects this now outmoded belief.) The claim wasn’t that a real dog and a stuff
ed-animal dog differed in every single bit, just that some components of living creatures were different. Those magical parts could only be found in living animals, and never in the laboratory, presumably because their preparation required a dollop of vital force.
One much-cited example was urea, a substance found in urine and, as far as was known, nowhere else in the world. But in 1828 a German scientist named Friedrich Wöhler managed to produce urea from indisputably nonliving materials. “I can make urea without need of a kidney or even an animal, be it man or dog,” Wöhler wrote proudly to a friend.
Wöhler had delivered a body blow to the age-old belief that the mysteries of life lay beyond the reach of science, and biologists and chemists greeted his coup with jubilation and astonishment. Another blow followed soon after.
This latest assault was a redo of a classic experiment. Decades before Wöhler, at about the time of the French Revolution, the modern science of chemistry had taken its first baby steps. Antoine Lavoisier was one of the proud parents. Lavoisier was a genius, a nobleman at a time when that meant trouble, and a meticulous researcher. In a dazzling career, he had racked up countless breakthroughs. Lavoisier had been the first to explain the ancient mystery of fire. What goes on when something bursts into flame? And it was Lavoisier who had established the fundamental truth that, no matter how you burn or break or freeze or cook anything whatever, it weighs precisely as much afterward as it did at the beginning. You can transform matter, but nothing you do can conjure up something out of nothing (at least not anything that shows up on a scale) or make anything vanish.*
In one painstaking experiment, Lavoisier compared the heat output from a living animal with that from a piece of burning coal. He put a guinea pig in a container with ice-filled walls and then did the same with a lump of coal, and measured how much ice each one melted. (To make sure that he was not just putting ice out to melt in the sun, Lavoisier performed his experiment on a freezing-cold winter’s day.) Then he put the guinea pig and the burning coal inside a bell jar and measured how much carbon dioxide they produced. The result was that breathing and burning produced about the same amount of heat for a given amount of carbon dioxide. Breathing was slow burning.