The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code (5 page)

Morgan no doubt consulted with his other trusted assistant, Alfred Sturtevant. Like Bridges, Sturtevant had worked with Morgan for decades, and the trio had shared in some of the most important discoveries in genetics history. Sturtevant and Morgan both scowled in private over Bridges’s dalliances and escapades, but their loyalty trumped any other consideration here. They decided that Morgan should throw his weight around. In short order, he threatened to expose the woman to the police, and kept up the pressure until Miss Princess disappeared on the next train. Morgan then hid Bridges away until the situation blew over.
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When he’d hired Bridges as a factotum years before, Morgan could never have expected he’d someday be acting as a goodfella for him. Then again, Morgan could never have expected how most everything in his life had turned out. After laboring away in anonymity, he had now become a grand panjandrum of genetics. After working in comically cramped quarters in Manhattan, he now oversaw a spacious lab in California. After lavishing so much attention and affection on his “fly boys” over the years, he was now fending off charges from former assistants that he’d stolen credit for others’ ideas. And after fighting so hard for so long against the overreach of ambitious scientific theories, he’d now surrendered to, and even helped expand, the two most ambitious theories in all biology.

Morgan’s younger self might well have despised his older self for this last thing. Morgan had begun his career at a curious time in science history, around 1900, when a most uncivil civil
war broke out between Mendel’s genetics and Darwin’s natural selection: things got so nasty, most biologists felt that one theory or the other would have to be exterminated. In this war Morgan had tried to stay Switzerland, refusing at first to accept either theory. Both relied too much on speculation, he felt, and Morgan had an almost reactionary distrust of speculation. If he couldn’t see proof for a theory in front of his corneas, he wanted to banish it from science. Indeed, if scientific advances often require a brilliant theorist to emerge and explain his vision with perfect clarity, the opposite was true for Morgan, who was cussedly stubborn and notoriously muddled in his reasoning—anything but literally visible proof bemused him.

And yet that very confusion makes him the perfect guide to follow along behind during the War of the Roses interlude when Darwinists and Mendelists despised each other. Morgan mistrusted genetics and natural selection equally at first, but his patient experiments on fruit flies teased out the half-truths of each. He eventually succeeded—or rather, he and his talented team of assistants succeeded—in weaving genetics and evolution together into the grand tapestry of modern biology.

The decline of Darwinism, now known as the “eclipse” of Darwinism, began in the late 1800s and began for quite rational reasons. Above all, while biologists gave Darwin credit for proving that evolution happened, they disparaged his mechanism for evolution—natural selection, the survival of the fittest—as woefully inadequate for bringing about the changes he claimed.

Critics harped especially on their belief that natural selection merely executed the unfit; it seemed to illuminate nothing about where new or advantageous traits come from. As one wit said, natural selection accounted for the survival, but not the
arrival,
of the fittest. Darwin had compounded the problem by
insisting that natural selection worked excruciatingly slowly, on tiny differences among individuals. No one else believed that such minute variations could have any practical long-term difference—they believed in evolution by jerks and jumps. Even Darwin’s bulldog Thomas Henry Huxley recalled trying, “much to Mr. Darwin’s disgust,” to convince Darwin that species sometimes advanced by jumps. Darwin wouldn’t budge—he accepted only infinitesimal steps.

Additional arguments against natural selection gathered strength after Darwin died in 1882. As statisticians had demonstrated, most traits for species formed a bell curve:
. Most people stood an average height, for example, and the number of tall or short people dropped smoothly to small numbers on both sides. Traits in animals like speed (or strength or smarts) also formed bell curves, with a large number of average creatures. Obviously natural selection would weed out the slowpokes and idiots when predators snatched them. For evolution to occur, though, most scientists argued that the average had to shift; your average creature had to become faster or stronger or smarter. Otherwise the species largely remained the same. But killing off the slowest creatures wouldn’t suddenly make those that escaped any faster—and the escapees would continue having mediocre children as a result. What’s more, most scientists assumed that the speed of any rare fast creature would be diluted when it bred with slower ones, producing more mediocrities. According to this logic, species got stuck in ruts of average traits, and the nudge of natural selection couldn’t improve them. True evolution, then—men from monkeys—had to proceed by jumps.
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Beyond its apparent statistical problems, Darwinism had something else working against it: emotion. People loathed natural selection. Pitiless death seemed paramount, with superior types always crushing the weak. Intellectuals like playwright George Bernard Shaw even felt betrayed by Darwin. Shaw had
adored Darwin at first for smiting religious dogmas. But the more Shaw heard, the less he liked natural selection. And “when its whole significance dawns on you,” Shaw later lamented, “your heart sinks into a heap of sand within you. There is a hideous fatalism about it, a ghastly and damnable reduction of beauty and intelligence.” Nature governed by such rules, he said, would be “a universal struggle for hogwash.”

The triplicate rediscovery of Mendel in 1900 further galvanized the anti-Darwinists by providing a scientific alternative—and soon an outright rival. Mendel’s work emphasized not murder and starvation but growth and generation. Moreover, Mendel’s peas showed signs of jerkiness—tall or short stalks, yellow or green peas, nothing in between. Already by 1902 the English biologist William Bateson had helped a doctor identify the first known gene in humans (for an alarming but largely benign disorder, alkaptonuria, which can turn children’s urine black). Bateson soon rebranded Mendelism “genetics” and became Mendel’s bulldog in Europe, tirelessly championing the monk’s work, even taking up chess and cigars simply because Mendel loved both. Others supported Bateson’s creepy zealotry, however, because Darwinism violated the progressive ethos of the young century. Already by 1904, German scientist Eberhard Dennert could cackle, “We are standing at the death-bed of Darwinism, and making ready to send the friends of the patient a little money, to ensure a decent burial.” (A sentiment fit for a creationist today.) To be sure, a minority of biologists defended Darwin’s vision of gradual evolution against the Dennerts and Batesons of the world, and defended it fiercely—one historian commented on both sides’ “remarkable degree of bitchiness.” But these stubborn few could not prevent the eclipse of Darwinism from growing ever darker.

Still, while Mendel’s work galvanized the anti-Darwinists, it never quite united them. By the early 1900s, scientists had
discovered various important facts about genes and chromosomes, facts that still undergird genetics today. They determined that all creatures have genes; that genes can change, or mutate; that all chromosomes in cells come in pairs; and that all creatures inherit equal numbers of chromosomes from Mom and Dad. But there was no overarching sense of how these discoveries meshed; the individual pixels never resolved into a coherent picture. Instead a baffling array of half theories emerged, like “chromosome theory,” “mutation theory,” “gene theory,” and so on. Each championed one narrow aspect of heredity, and each drew distinctions that seem merely confusing today: some scientists believed (wrongly) that genes didn’t reside on chromosomes; others that each chromosome harbored just one gene; still others that chromosomes played no role in heredity at all. It’s whiggishly unfair to say, but reading these overlapping theories can be downright frustrating today. You want to scream at the scientists, like a dimwit on
Wheel of Fortune
or something, “Think! It’s all right there!” But each fiefdom discounted discoveries by rivals, and they squabbled against each other almost as much as against Darwinism.

As these revolutionaries and counterrevolutionaries bitched it out in Europe, the scientist who eventually ended the Darwin-genetics row was working in anonymity in America. Though he mistrusted both Darwinists and geneticists—too much bloviating about theory all around—Thomas Hunt Morgan had developed an interest in heredity after visiting a botanist in Holland in 1900. Hugo de Vries had been one of the trio who rediscovered Mendel that year, and de Vries’s fame in Europe rivaled Darwin’s, partly because de Vries had developed a rival theory for the origin of species. De Vriesian “mutation theory” argued that species went through rare but intense mutation periods, during which the parents produced “sports,” offspring with markedly different traits. De Vries developed mutation theory
after spotting some anomalous evening primroses in an abandoned potato field near Amsterdam. Some of these sport primroses sported smoother leaves, longer stems, or bigger yellow flowers with more petals. And crucially, primrose sports wouldn’t mate with the old, normal primroses; they seemed to have jumped past them and become a new species. Darwin had rejected evolutionary jumps because he believed that if one sport emerged, it would have to breed with normal individuals, diluting its good qualities. De Vries’s mutation period removed this objection at a stroke: many sports emerged at once, and they could breed only with each other.

The primrose results scored themselves into Morgan’s brain. That de Vries had no clue how or why mutations appeared mattered not a lick. At last Morgan saw proof of new species emerging, not speculation. After landing a post at Columbia University in New York, Morgan decided to study mutation periods in animals. He began experiments on mice, guinea pigs, and pigeons, but when he discovered how slowly they bred, he took a colleague’s suggestion and tried
Drosophila,
fruit flies.

Like many New Yorkers then, fruit flies had recently immigrated, in their case arriving on boats with the first banana crops in the 1870s. These exotic yellow fruits, usually wrapped in foil, had sold for ten cents per, and guards in New York stood watch over banana trees to prevent eager mobs from stealing the fruit. But by 1907 bananas and flies were common enough in New York that Morgan’s assistant could catch a whole horde for research simply by slicing up a banana and leaving it on a windowsill to rot.

Fruit flies proved perfect for Morgan’s work. They bred quickly—one generation every twelve days—and survived on food cheaper than peanuts. They also tolerated claustrophobic Manhattan real estate. Morgan’s lab—the “fly room,” 613 Schermerhorn Hall at Columbia—measured sixteen feet by twenty-three feet and had to accommodate eight desks. But a thousand fruit flies lived happily in a one-quart milk bottle, and Morgan’s shelves were soon lined with the dozens of bottles that (legend has it) his assistants “borrowed” from the student cafeteria and local stoops.