Would you inject 50 hookworms under your skin for your job? Or steam in a vomit sauna for a few hours? Hopefully we non-scientists will never have to answer questions like these. But for the 10 brave souls on this list, experimenting on themselves was all in a day's work.

1. Jonas Salk

During his research at the University of Pittsburgh Medical School, Dr. Jonas Salk discovered a potential vaccine for polio. When they needed healthy human test subjects, Salk volunteered himself and his entire family for a vaccine trial. The filial gamble paid off. Everyone tested positive for antibodies against the virus. He refused to patent the vaccine, and never received financial compensation for his discovery. (When Edward R. Murrow asked Salk who owned the patent on the vaccine, Salk responded with one of his most famous quotes: “Well, the people, I would say. There is no patent. Could you patent the sun?”)

2. David Pritchard

In 2004, after years of research in Papua New Guinea, immunologist-biologist David Pritchard wanted to test his findings: that certain parasites can improve the immune system's defense against allergies, and possibly more serious autoimmune illnesses. Circumventing the inevitable years of red tape, Pritchard used himself as the first test subject, injecting 50 hookworms under his skin. He was able to deduce that only 10 hookworms were necessary for future test subjects.

3. John Paul Stapp

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Air Force officer and surgeon John Paul Stapp's self-experimentation earned him the nickname "the fastest man on Earth." In his research, Stapp repeatedly strapped himself into a rocket sled, nicknamed the "Gee Whiz," and was propelled forward at speeds close to that of sound. He would then brake abruptly to determine the human body's ability to withstand abrupt deceleration. Many broken bones and a temporarily detached retina later, Stapp determined a human body can withstand 45 Gs of forward motion with an adequate harness.

4. August Bier

At the turn of the 20th century, August Bier developed a method for spinal anesthesia. It involved injecting cocaine into the cerebrospinal fluid. To test its effectiveness, Bier enlisted himself. During the experiment, a mix-up left Bier with a hole in his spine leaking cerebrospinal fluid. Bier's assistant stepped in to take his place in the study. Once the assistant was properly numb, Bier kicked his shins, bludgeoned and burned him, plucked out his pubic hairs, and mashed his genitals. The assistant felt nothing—a success the two celebrated by drinking excessively that evening.

5. Werner Forssmann

In 1929, in the basement of the Eberswalde Hospital in Germany, surgical resident Werner Forssmann inserted a ureteral catheter tube into his elbow, feeding it through a vein up to his heart. He used a mirror as his assistant, since he had restrained his nurse to the operating table. He then took an x-ray of his chest to determine that the catheter had indeed made it to the right atrium. Instead of praise, Forssmann was met with condemnation by medical ethicists. This rejection led him to abandon cardiology for urology, but he was later honored with the Nobel Prize in 1956.

6. Nathaniel Kleitman

In 1938, sleep researcher Nathaniel Kleitman and his assistant holed up in Mammoth Cave in Kentucky. They were attempting to manipulate their sleep cycles to adopt a 28-hour day. With constant temperature and no natural light, the conditions in the cave seemed perfect. After 32 days, Kleitman's assistant had successfully adapted, but Kleitman failed. Nonetheless, the experiment's results helped to advance their study of circadian rhythms.

7. Humphry Davy

A 19th-century illustration satirizes Humphry Davy's experiments with nitrous oxide. Davy operates the bellows filled with laughing gas, which flows through a tube in his assistant's mouth, resulting in the gas exploding out of his bum.Oxford Science Archive/Print Collector/Getty Images

While at the Medical Pneumatic Institute of Bristol, UK, Humphry Davy studied gases. Through a series of self-experiments with oxides of nitrogen, Davy created what is known today as laughing gas. Though his initial attempts were meant to reproduce the pleasurable effects of opium and alcohol, Davy would ultimately recommend the use of nitrous oxide as an anesthetic. His recommendation would not be heeded until long after his death, but nitrous became an instant hit at fashionable parties.

8. Kevin Warwick

In the late 1990s, Kevin Warwick had his team surgically implant a silicon chip transponder into his forearm for an experiment known as Project Cyborg. Through this implant, Warwick's nervous system was monitored by a computer system. According to his website, the neural interface allowed him to "operate doors, lights, heaters, and other computers without lifting a finger." In other words, the future is now.

9. Albert Hoffman

Swiss chemist Albert Hoffman was researching the fungus ergot for a pharmaceutical company when he discovered lysergic acid. His initial tests were inconclusive, but Hoffman decided to retest a synthesized version of the acid. In April 1943, he ingested 25 milligrams of a substance he called LSD-25 in his lab. Legend has it, on his bike ride home, his eyes were opened up to a brave new hallucinogenic world. To this day, LSD enthusiasts observe April 19 as "Bicycle Day." Hoffman would continue to experiment with LSD until his death at 102.

10. Stubbins Ffirth

After witnessing a devastating yellow fever epidemic in 1793, Stubbins Ffirth hypothesized the viral hemorrhagic disease was not contagious. To prove his thesis, he tested the disease's characteristic black vomit. On himself. This included, but certainly was not limited to, pouring vomit into his open cuts or onto his eyeballs, drinking infected black vomit by the glassful, and stewing up to his waist in a veritable sauna of vomit. He would later rub blood and urine on his body as well, but ultimately avoided infection. In his 1804 book A Treatise on Malignant Fever; with an Attempt to Prove Its Non-Contagious Nature, he declared yellow fever not contagious. (Later researchers discovered that it was contagious, but only through bites from infected mosquitos.)