When Vladimir Demikhov unveiled his two-headed dogs in 1954, it inspired a strange kind of surgical arms race between the two superpowers. Or rather, a head race. Eager to prove that its surgeons were actually the best in the world, the American government began funding the work of Robert White, who then embarked on a series of experimental surgeries, performed at his brain research center in Cleveland, Ohio, resulting in the world's first successful monkey-head transplant.

The head transplant occurred on March 14, 1970. It took White and his assistants hours to perform the carefully choreographed operation, separating a monkey's head from its body and reattaching it to a new body. When the monkey woke and found that its body had been switched for a new one, it angrily tracked White with its eyes and snapped at him with its teeth. The monkey survived a day and a half before succumbing to complications from the surgery. As bad as it was for the monkey, it could have been worse. White noted that, from a surgical point of view, it would have been easier to put the monkey's head on backwards.

White thought he should have been treated like a hero, but instead the public was appalled by what he had done. Nevertheless, White soldiered on, campaigning to raise support for a human head transplant. He toured with Craig Vetovitz, a near-quadriplegic, who volunteered to be the first to undergo the procedure. But to date, a human-head transplant has not yet been performed.

Yale researcher Jose Delgado stood in the hot sun of a bullring in Cordova, Spain. With him in the ring was a large, angry bull. The animal noticed him and began to charge. It gathered speed. Delgado appeared defenseless, but when the bull was mere feet away, Delgado pressed a button on a remote control unit in his hand, sending a signal to a chip implanted in the bull's brain. Abruptly, the animal stopped in its tracks. It huffed and puffed a few times, and then walked docilely away.

Delgado's experience in the ring was an experimental demonstration of the ability of his "stimoceiver" to manipulate behavior. The stimoceiver was a computer chip, operated by a remote-control unit, that could be used to electrically stimulate different regions of an animal's brain. Such stimulation could produce a wide variety of effects, including the involuntary movement of limbs, the eliciting of emotions such as love or rage, or the inhibition of appetite. It could also be used, as Delgado showed, to stop a charging bull.

Delgado's experiment sounds so much like science fiction, that many people are surprised to learn it occurred back in 1963. During the 1970s and 80s, research into electrical stimulation of the brain (ESB) languished, stigmatized by the perception that it represented an effort to control people's minds and thoughts. But more recently, ESB research has once again been flourishing, with reports of researchers creating remote-controlled rats, pigeons, and even sharks.

History contains a number of accounts of children raised by animals. The children in such cases often end up behaving more animal than human, even when returned to human society. This made the psychologist Winthrop Kellogg wondered what would happen if the situation were reversed. What if an animal were raised by humans —as a human? Would it eventually act like a human?

To answer this question, in 1931 Kellogg brought a seven-month-old female chimpanzee named Gua into his home. He and his wife then proceeded to raise her as if she were human, treating her exactly the same as they treated their ten-month-old son Donald.

Donald and Gua played together. They were fed together. And the Kelloggs subjected them both to regular tests to track their development. One such test was the suspended cookie test, in which the Kelloggs timed how long it took their children to reach a cookie suspended by a string in the middle of the room.

Gua regularly performed better on such tests than Donald, but in terms of language acquisition she was a disappointment. Despite the Kelloggs's repeated efforts, the ability to speak eluded her. Disturbingly, it also seemed to be eluding Donald. Nine months into the experiment, his language skills weren't much better than Gua's. When he one day indicated he was hungry by imitating Gua's "food bark," the Kelloggs decided the experiment had gone far enough. Donald evidently needed some playmates of his own species. So on March 28, 1932 they shipped Gua back to the primate center. She died a year-and-a-half later of fever.

In the summer of 1942, Professor Lawrence Leshan stood in the darkness of a cabin in an upstate New York camp where a row of young boys lay sleeping. He spoke aloud, repeating a single phrase over and over: "My fingernails taste terribly bitter. My fingernails taste terribly bitter."

Leshan wasn't mad. He was conducting a sleep-learning experiment. All the boys had been diagnosed as chronic nail-biters, and Leshan wanted to find out if nocturnal exposure to a negative suggestion about nail biting would cure them of their bad habit.

Leshan initially used a phonograph to play the message. It faithfully repeated the phrase 300 times a night as the boys lay sleeping. But five weeks into the experiment, the phonograph broke. Leshan improvised by standing in the darkness and speaking the message himself.

At the end of the summer, Leshan examined the boys' nails and concluded that 40% of them had kicked the habit. The sleep-learning effect seemed to be real. However, other researchers later disputed this conclusion. In a 1956 experiment at Santa Monica College, William Emmons and Charles Simon used an electroencephalograph to make sure subjects were fully asleep before playing a message. Under these conditions, the sleep-learning effect disappeared.

In 1780, the Italian anatomy professor Luigi Galvani discovered that a spark of electricity could cause the limbs of a dead frog to twitch. Soon men of science throughout Europe were repeating his experiment, but it didn't take them long to bore of frogs and turn their attention to more interesting animals. For instance, they wondered what would happen if you electrified a human corpse.

Galvani's nephew, Giovanni Aldini, embarked on a tour of Europe in which he offered audiences the chance to see this stomach-turning spectacle. His most celebrated demonstration occurred on January 17, 1803 when he applied the poles of a 120-volt battery to the body of the executed murderer George Forster.

When Aldini placed wires on the mouth and ear, the jaw muscles quivered and the murderer's features twisted in a rictus of pain. The left eye opened as if to gaze upon his torturer. For the grand finale Aldini hooked one wire to the ear and plunged the other up the rectum. Forster's corpse broke into a hideous dance. The London Times wrote, "It appeared to the uninformed part of the bystanders as if the wretched man was on the eve of being restored to life."

Other researchers tried electrifying corpses with the hope of restoring them to life, but with no success. Early nineteenth-century experiments of this kind are considered to have been one of Mary Shelley's main sources of inspiration when she wrote her novel Frankenstein in 1816.

In 1999 researchers led by Dr. Yang Dan, an assistant professor of neurobiology at the University of California, Berkeley, anesthetized a cat with sodium pentothal, chemically paralyzed it with Norcuron, and secured it tightly in a surgical frame. They then glued metal posts to the whites of its eyes, and forced it to look a screen that showed scene after scene of swaying trees and turtleneck-wearing men.

This wasn't a form of Clockword-Orange-style aversion therapy for cats. Instead, it was an attempt to tap into another creature's brain and see directly through its eyes. The researchers had inserted fiber electrodes into the vision-processing center of the cat's brain. The electrodes measured the electrical activity of the brain cells and transmitted this information to a nearby computer which decoded the information and transformed it into a visual image. As the cat watched the images of the trees and the turtleneck-wearing guy, the same images emerged (slightly blurrier) on the computer screen across the room.

The researchers suggested that the picture quality could be improved in future experiments by measuring the activity of a larger number of brain cells.

Male turkeys aren't fussy. Give them a lifelike model of a female turkey and they'll happily try to mate with it as eagerly as they would with the real thing.

This observation intrigued Martin Schein and Edgar Hale of the University of Pennsylvania, and made them curious about what might be the minimal stimulus required to excite a turkey. They embarked on a series of experiments to find out. This involved removing parts from the turkey model one by one, until the male turkey eventually lost interest.

Tail, feet, and wings were all removed, but still the male bird waddled up to the model, let out an amorous gobble, and tried to do his thing. Finally, the researchers were left with a head on a stick. And surprisingly, the turkey still showed great interest. In fact, it preferred a head on a stick over a headless body.

Schein and Hale subsequently investigated how minimal they could make the head itself before it failed to elicit a response. They discovered that freshly severed female heads impaled on sticks worked best, but if the male turkey had nothing else it would settle for a plain balsa wood head.

Imagine that it's 1978, and you're a young man walking across the campus of Florida State University. A beautiful female stranger approaches you and says these exact words, "I have been noticing you around campus. I find you to be attractive. Would you go to bed with me tonight?"

If you were that man, you might have thought you had just gotten incredibly lucky. But not really. You were actually an unwitting subject in an experiment designed by the psychologist Russell Clark.

Clark had persuaded the students of his social psychology class to help him find out which gender, in a real-life situation, would be more receptive to a sexual offer from a stranger. The only way to find out, he figured, was to actually get out there and see what would happen. So young men and women from his class fanned out across campus and began propositioning strangers.

The results were predictable. Seventy-five percent of guys were happy to oblige an attractive female stranger. The few who said no typically offered an excuse such as, "I'm married." But not a single woman accepted the identical offer of an attractive male. In fact, most of them demanded the guy leave her alone.

At first the psychological community dismissed Clark's experiment as a trivial stunt, but gradually his experiment gained acceptance, and eventually praise for how dramatically it revealed the differing sexual attitudes of men and women. Today it's considered a classic. But why men and women display such different attitudes remains as hotly debated as ever.

Charles Sheridan and Richard King told their subjects (—undergraduate volunteers from a psychology course)— that a puppy was being trained to distinguish between a flickering and a steady light. It had to stand in one of two places depending on the cue from the light. If it failed to stand in the correct place, the subjects were instructed to press a switch to shock it. The power level increased 15 volts with each successive shock — supposedly testing whether increasing pain would motivate the puppy to learn more quickly.

In reality, this wasn't a test of puppy learning. It was an experiment inspired by Stanley Milgram's "obedience experiment" of 1963, which had demonstrated that a majority of people would obediently deliver shocks of increasing intensity to another person, up to a potentially fatal level, at the mere command of a researcher. Milgram's victim (an actor) had faked his cries of pain, leading some critics to suggest that perhaps the subjects had obeyed the researcher because they realized that the experimental setup was a ruse. So Sheridan and King had decided to repeat Milgram's experiment, introducing one signifcant difference. Instead of using an actor, they would use an actual victim — a puppy — who would really get shocked.

As the voltage increased, the puppy first barked, then jumped up and down, and finally started howling with pain. The student volunteers were horrified. They paced back and forth, hyperventilated, and gestured with their hands to show the puppy where to stand. Many openly wept. Yet the majority of them, twenty out of twenty-six, kept pushing the shock button right up to the maximum voltage.

On October 31, 1938, John Deering took a last drag on his cigarette, sat down in a chair, and allowed a prison guard to place a black hood over his head and pin a target to his chest. Next the guard attached electronic sensors to Deering's wrists.

Deering had volunteered to participate in an experiment, the first of its kind, to have his heartbeat recorded as he was shot through the chest by a firing squad. The prison physician, Dr. Stephen Besley, figured that since Deering was being executed anyway, science might as well benefit from the event. Perhaps some valuable information about the effect of fear on the heart could be learned.

The electrocardiogram immediately disclosed that, despite Deering's calm exterior, his heart was beating like a jackhammer at 120 beats per minute. The sheriff gave the order to fire, and Deering's heartbeat raced up to 180 beats per minute. Then four bullets ripped into his chest, knocking him back in his chair. One bullet bore directly into the right side of his heart. For four seconds his heart spasmed. A moment later it spasmed again. Then the rhythm gradually declined until, 15.4 seconds after the first shot, Deering's heart stopped.

The next day Dr. Besley offered the press a eulogy of sorts for Deering, saying, "He put on a good front. The electrocardiograph film shows his bold demeanor hid the actual emotions pounding within him. He was scared to death."