Sperry repeated this experiment with a monkey, cutting the optic chiasm and the corpus callosum. This time he also gave one half of the monkey’s brain a frontal lobotomy. He put an eye patch on the monkey and showed it a snake. Monkeys have an instinctive fear of snakes. If the sight of the snake went to the undamaged half of its brain, the monkey screamed, defecated, and tried to escape. But if the sight went to the lobotomized hemisphere, the monkey gave the snake a “What, me worry?” look. It was as if the monkey had two separate brains, or as if there were two monkeys in one body.
In the early years of the twentieth century, the pioneering Spanish neuroanatomist Santiago Ramón y Cajal was the first to stain, draw, and number individual nerve cells in the brain. (Here, nerves from the brains of a bee and a fly.) In the early 1960s, Seymour Benzer and other molecular biologists studied Cajal’s wiring diagrams and wondered if they could now trace the connections between genes, nerves, and behavior. (Illustrations credit 6.1)
The Machinery of the Brain gave Benzer the same sense that Arrowsmith had given him as a teenager in Brooklyn and What Is Life? as a young physicist in Lafayette: the sense of having discovered a personal road map. The author, Wooldridge, had once been in charge of research and development for the Hughes Aircraft Company. He was a founder and president of a major high-technology corporation, Thompson Ramo Wooldridge. Wooldridge had quit to hang around laboratories like Sperry’s at Caltech. He wrote that he meant his book to be “a travelogue—a description of an exotic land by one who visits it for the first time.” He hoped it would serve another lapsed physicist somewhere as a point of departure “for more intensive studies.”
In 1965, Benzer took a year’s leave of absence from Purdue and visited Sperry’s laboratory on the third floor of Church Hall. Delbrück was there, too, down in the basement, working on the fungus that grows toward light.
In Sperry’s lab, Benzer watched biologists study the brains of goldfish, monkeys, frogs, chicks, chameleons, cats, and human beings. The work on human beings later won Sperry a Nobel Prize. He had begun to study epileptics whose brains’ right and left hemispheres had been surgically severed. Cutting the corpus callosum prevents epileptic seizures from spreading from one side of the brain to the other. Surgeons had been performing these operations for years in the belief that their patients’ behavior would not be affected. One authority on the brain joked that the only role of the human corpus callosum seemed to be to pass epileptic seizures from one side of the brain to the other. Another authority said that its only role was to keep the two halves of the brain from sagging.
But Sperry showed that under special conditions the behavior of split-brain patients is bizarre. A hybrid face is flashed on a screen: One side is a man’s, the other side a woman’s. The patient is presented this image in such a way that his left brain sees only the man’s face and his right brain sees only the woman’s. If the patient is asked to report what he just saw he will say, “A man,” because the left hemisphere is dominant in language. But if the patient is asked to point to a face that matches the one he just saw, he will point to the woman, because the right hemisphere is dominant for action and movement. Now the word “WALK” is flashed on the screen in such a way that only the patient’s right brain sees it. Soon afterward he gets up and begins to walk away. The experimenter asks him why he got up. “I’m going to get a Coke,” he says. He cannot explain the real reason because only his right brain knows, and his right brain is mute.
The human brain, like the brain of a monkey, a cat, even a toad or a fly, is made of many separate working parts. Today some neuroanatomists speak of modules. Just as each lobe of the human brain has its own characteristic infoldings, each lobe and each region of the brain and brain stem has its own characteristic function: there is no breathing without the medulla oblongata, no sensation of smooth movement without the pons, no eye movement without the midbrain. The modules may be even finer-scale than that, as Sperry and others were beginning to discover. This is the essence of the idea that Freud and his followers were exploring from the outside by introspection: that we have conflicting motives and drives, and that we are aware of only a small subset of them at a time. Sensitive human beings have always known this and have felt the strain of their own incongruities. Henry David Thoreau writes in his poem “Sic Vita” (Such Is Life):
I am a parcel of vain strivings tied
By a chance bond together,
Dangling this way and that, their links
Were made so loose and wide.
We have all had occasion to feel that the right hand does not know what the left hand is doing. We made a resolution not to eat or drink, and then we watched the hand pour or eat—while we invented stories to account for and explain the act to ourselves, like Sperry’s subject on his way to the Coke. Each of us is a loose parcel of strivings that normally display themselves to us not all at once but across time. Some of these drives seem to visit us from a long way back in time, and some threaten to wreak havoc with the rest. A life is a great parliament of instincts, as Konrad Lorenz once put it. This parliament is what Benzer proposed to explore through the genes.
IN SPERRY’S LABORATORY, Benzer prowled from bench to bench. He knew that phage had spoiled him. With phage he could hold billions of test subjects in a dish no bigger than the palm of his hand. He could breed dozens of generations in a day and find one freak in a billion at a glance. After enjoying that kind of speed, convenience, and instant gratification, he could not imagine trying to breed and cross goldfish, monkeys, frogs, chicks, cats, or chameleons. And as he said later, drily, “Humans were ruled out because it is so difficult to convince them to mate in the right combinations, generations take too long a time, and the offspring are too few.”
Benzer considered ants, spiders, and bees. Bees interested him, but unlike Mendel he did not love the idea of building hives and mating chambers. For a while he kept spiders spinning webs in jars, admiring their wonderful fixed-action patterns. But he thought spiders would be almost as inconvenient for his purposes as bees. “I searched the literature,” he says. “No one had ever done a Mendelian cross between two spiders. One reason was that the females ate the males.”
While he thought about his problem, he kept reading voraciously. He admired The Expression of the Emotions in Man and Animals, which Darwin had published in 1872. Those were the days when the sun never set on the British Empire, and Darwin had sent out a questionnaire to explorers, missionaries, and “protectors of the aborigines” in every corner of it:
(1.) Is astonishment expressed by the eyes and mouth being open wide, and by the eyebrows being raised?
(2.) Does shame excite a blush when the color of the skin allows it to be visible? and especially how low down the body does the blush extend?
(3.) When a man is indignant or defiant does he frown, hold his body and head erect, square his shoulders and clench his fists?
(4.) When considering deeply on any subject, or trying to understand any puzzle, does he frown, or wrinkle the skin beneath the lower eyelids?
And so on. The replies that Darwin received from Australia, New Zealand, India, Africa, the Malays, China, and the American Northwest were all affirmative. People’s expressions are broadly the same all over the planet, which is one reason that Hollywood’s empire is at least as large today as the British Empire was in 1872.
The fundamentals of human expressions are inherited, and Benzer was sure there was much more to explore. The flinch reflex, for instance, is obviously adaptive and hard-wired. Many of us flinch when we see a snake, and some of us react like Sperry’s monkey. Again the reaction is probably hard-wired and adaptive—at least, it was adaptive for millions of years of human evolution until we got out of the trees and into the cities. We have been living in cities for only a short fraction of the life of our species, and evolution has only partly dampened the reflex in most of us, like a partial lobotomy. In The Expression of the Emotions, Darwin describes an experiment at the London Zoo: “
I put my face close to the thick glass-plate in front of a puff-adder in the Zoological Gardens, with the firm determination of not starting back if the snake struck at me; but, as soon as the blow was struck, my resolution went for nothing, and I jumped a yard or two backwards with astonishing rapidity. My will and reason were powerless against the imagination of a danger which had never been experienced.”
Benzer also enjoyed reading books by Darwin’s cousin. Galton did bizarre introspective experiments to get at the bits of inheritance that he was convinced must underlie behavior. By exploring his own mind and quizzing others, he explored the ways we are all alike and the ways we differ. Not everyone answered Galton’s questionnaires. Darwin refused (“I have never tried looking into my own mind.”). Still Galton found that most people seemed to enjoy introspecting. “I think that a delight in self-dissection must be a strong ingredient in the pleasure that many are said to take in confessing themselves to priests.”
For instance, Galton corresponded with a calculating prodigy who was the son of a calculating prodigy. The man told him that he always saw numbers in his mind’s eye, and he sent Galton a drawing. “It began,” Galton writes, “with the face of a clock, numbered I to XII, and then tailed off, much like the tail of a kite, into an undulating curve, having 20, 30, 40, etc., at each bend.” Galton was surprised to discover that these number visions are fairly common. When he asked about them in a large lecture “up went a multitude of scattered hands all about the body of the hall.” And number forms seemed to run in families. They reflected something about the quirky individual construction of individual minds, and the quirks could be traced—as we say now—to genes. Years later Benzer would do an informal survey and discover number visionaries in his wife’s family.
Time and again Galton’s experiments gave Benzer glimpses of what Galton called “the number of operations of the mind, and of the obscure depths in which they took place, of which I had been little conscious before.” It was like walking down into the basement when the plumber was there, Galton wrote prosaically, and seeing for the first time “the complex system of drains and gas and water pipes, flues, bell-wires, and so forth, upon which our comfort depends, but which are usually hidden out of sight, and with whose existence, so long as they acted well, we had never troubled ourselves.” And what a difference between the view of the people of the house and the view of the plumber!
“Laypeople—I don’t mean very sophisticated people, but ordinary laypeople—think if something is natural it doesn’t require an explanation,” says Francis Crick. “You know: ‘What is there to worry about? It’s perfectly natural!’ You see? Whereas we know that some things that are natural are often extremely intricate in the mechanisms that are needed to make this natural behavior—as we soon find out if something goes wrong. But that’s the reaction of many laypeople, that they think their behavior is basically simple. They do it, it’s perfectly natural, what is it to explain? And to think that it’s due to genes, or something else, that’s really terrible.” Crick laughs. “Although all parents will remark to you how different their children are. And they notice it from an extremely early age.”
Darwin’s cousin Francis Galton was convinced that each mind has quirks and that many of the quirks are inherited. Galton reported that one out of every fifteen women and one out of every thirty men sees what he called “number-forms” in the mind’s eye. Whenever these number visionaries think of a number, they always see it floating in the same place in imaginary space. One subject told Galton that he always saw the number one floating low and to the left, the number one hundred floating low and to the right, with every digit in between forming a complicated spectral arc. Number forms like these may run in families. (Illustrations credit 6.2)
Galton knew nothing about the genes that underlie all these operations of the brain. But Benzer was sure that Galton was right: There are bound to be genetic differences for a thousand mental operations and a thousand individual quirks too. Galton urged future generations of scientists to study the variability of human instincts. Like Darwin, he singled out the fear of snakes. “I myself have a horror of them,” Galton wrote, “and can only by great self-control, and under a sense of real agitation, force myself to touch one.” Sometimes Galton forced himself to watch rabbits and birds being fed to the snakes at the London Zoo. He found the sight horrible but fascinating, and he could not understand how children and their nurses could stand right next to him and smile or stroll on by. “Their indifference was perhaps the most painful element of the whole transaction. Their sympathies were absolutely unawakened.”
“When you have one child, it behaves like a child,” Benzer says. “But as soon as you have a second child you realize from Day One that this one is different from the other. “The Benzer family’s “Season’s Greetings” photograph, 1954. (Illustrations credit 6.3)
Galton also had a horror of blood, and he thought that this might be another human instinct: “but I have seen a well-dressed child of about four years old poking its finger with a pleased innocent look into the bleeding carcase of a sheep hung up in a butcher’s shop, while its nurse was inside.” Galton thought schoolteachers should take surveys of children’s nightmares and goose bumps: “It would be necessary to approach the subject wholly without prejudice, as a pure matter of observation, just as if the children were the fauna and flora of hitherto undescribed species in an entirely new land.”
Benzer knew he had to start with something simpler.
WHENEVER HE WANDERED out of Sperry’s laboratory, he would pass the relics of Morgan’s last Fly Room. Morgan’s collected works, beginning with his first notes on mice and starfish, reposed in rows of file cabinets up and down the corridor. Morgan himself was long since dead, but Alfred Sturtevant, the old veteran of Morgan’s Raiders, still came around often, a pipe clenched between his teeth, to see what was new and interesting in genetics, and to tend an experimental bed of irises that he had planted just outside the building. One of Sturtevant’s best students, Ed Lewis, had inherited his old lab space on the third floor, along with thousands and thousands of mutant flies—and of course the milk bottles.
Benzer watched Lewis sort flies, and Lewis watched Benzer watch him. Since the discovery of the double helix, the gulf between molecular biology and the rest of biology had widened every year. Molecular biologists were known as bad boys, bullyboys, arms of the flood. At Harvard, Jim Watson was trying with enormous energy and without enormous tact to pack the biology department with molecular people and get rid of all the deadwood: the field biologists, taxonomists, ecologists, ethologists, and naturalists. Among the young professors who arrived at Harvard at the same time as Watson was E. O. Wilson, who would become, among other things, one of the century’s great field biologists, taxonomists, ecologists, ethologists, and naturalists. At one faculty meeting Wilson proposed hiring another ecologist. He heard Watson say softly, as if to himself, “Are they out of their minds?”
“What do you mean?” Wilson asked.
“Anyone who would hire an ecologist is out of his mind.”
Wilson had read What Is Life? in college at the University of Alabama in Tuscaloosa, and he had been just as thrilled as Watson, Crick, and Benzer (“Imagine: biology transformed by the same mental effort that split the atom!”). Both Wilson and Watson would end their careers convinced that the search for the atoms of behavior is the central quest of science. But in those days, Watson had nothing to say to Wilson when they passed in the halls at Harvard, even when they were the only two people in the hall. Wilson’s memoir Naturalist includes a chapter “The Molecular Wars.” The chapter begins, “Without a trace of irony I can say I have been blessed with brilliant enemies.” James Dewey Watson was one of them. “When he was a young man, in the 1950s and 1960s,” Wilson writes, “I found him the most unpleasant human being I had ever met.”
Not since the Age of Enlightenment had the world seen such a crew of intellectual cutthroats, divinely assured of their rights of succes
sion and their place in history. The philosophes of the Enlightenment also had their share of tall, thin, prognathous young men, and many of their contemporaries found them (in the words of Horace Walpole) “solemn, arrogant, dictatorial coxcombs—I need not say superlatively disagreeable.”
Seymour Benzer was not an unpleasant human being, but he was one of the revolutionaries. In Church Hall he and Delbrück and sometimes Watson (when he came to visit) strode through the corridors talking about events “in the days of genetics” as if those days were ancient history—even though Ed Lewis was still sitting in his lab crossing mutant flies, and the man who had made the first map of the genes was kneeling just outside the building, weeding his irises. Someone in the public relations department at Caltech once interviewed Benzer as part of an in-house oral history project. She asked Benzer if Lewis had been held in contempt by the new breed of molecular biologists in the 1960s. “No. He was a nice guy,” Benzer replied. “He was very good with flies. But at the time it seemed sort of like having a Greek mythology scholar: it’s nice to have one around for the university at large. He taught the genetics class, and kids counted the flies. Of course I’m giving you the jaundiced point of view. He was the true inheritor of the Morgan-Sturtevant tradition, and that was just fine.”
Lewis himself felt his isolation painfully. “Drosophila went into almost total eclipse,” he says. “Delbrück would pound the table: ‘Genetics is dead! Genetics is dead! Genetics is dead!’ ” Over and over, Delbrück said it in so many words: Molecular biology is the only biology.
(Many years later, around the corner from the campus, sitting in Max Delbrück’s favorite old rocking chair, Manny Delbrück would giggle when she remembered the apocalyptic speeches her husband used to make. “You see,” she said, “Max didn’t know any other biology.”)
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