We know all about the human body, what’s in there, how it works, and how to heal it when it’s sick. But of course, this wasn’t always so. It’s really only been in the last few centuries that scientists have been able to explore and experiment on humans. I mean, rats and mice may be a good place to start down on the road to new discoveries, but after a point, to really learn about humans, you have to try stuff out on humans. And as you might expect, human testing is currently and has always been a tricky business At their best, researchers have searched for lifesaving cures and treatments for uncomfortable and deadly conditions At their worst, human studies have edged into dark, curiosity-satisfying torture experiments that yielded few useful results.When it comes down to it, the science performed on humans has ranged from good to bad to very, very ugly [SciShow Theme] Way back in the day, physicians like Aristotle got most of their information about our bodies from a combination of dissecting other animals’ bodies and guesswork But you can study monkeys and pigs all you want and not get a very good picture of what’s really going on all up in here. So one of the very earliest uses of the human body in science was the simple study of human anatomy. For more than a thousand years it was one of the most controversial areas of scientific research This may in some part be because – ethically speaking – anatomical study got off to a very bad start. Around twenty three hundred years ago, Greek physicians Herophilus & Erasistratus got to see the inside of human bodies when they obtained permission to carry out LIVE dissections or vivisections on criminals.Herophilus was also the first known person to perform autopsies, and his descriptions of the nervous, digestive, reproductive and cardiovascular systems remained important and in some cases, singular, until the Middle Ages! But working on human bodies – living or dead – was widely considered taboo. Many contemporaries considered Herophilus to be a sadistic butcher, and people thought poking through the guts of even a dead person would anger the gods. By the time Roman law came along, human dissections of all types were banned, and the taboos studying the human body remained in place for the next 1600 years! It wasn’t until the late 15th century when Michelangelo, Leonardo da Vinci and Antonio Pollaiuolo started making secret anatomical drawings of cadavers, that the scientific mind began once again to probe our inner workings.Still, human anatomy wasn’t taught in universities until the mid 1620s and dissection was regarded rarely even then. It wasn’t until Englands Murder Act of 1752 that surgeons in that country were allowed to dissect the bodies of executed criminals. But it was around this time when scientists were finally able to address the essential questions of what goes where inside us, that the idea of actually experimenting on people became at least – thinkable. Perhaps most famous and important early example of experimentation is the origin of the smallpox vaccine. In 1796, English doctor Edward Jenner was seeing a lot of smallpox patients… Lots of pus, lots of dying. He started to thing about the folk adage, that people who caught cowpox couldn’t catch smallpox.Cowpox is a mild viral infection seen in cows, and other than getting some pus-y spots on your udders, it wasn’t so bad. Milk maids sometimes caught cowpox on their hands in particular after milking infected udders; and while it made them feel nasty, it wasn’t a big deal. So one spring day, Dr Jenner got a patient with cowpox on her hands, and he is all, a-HA! An opportunity! …to infect an unsuspecting human! Then, the gardeners 8-year-old-son walked by. Jenner scratched up Lil’ Jimmy’s arm and rubbed some pus in there. The kid got mildly ill with cowpox, but was fine a week later. Jenner then knew cowpox could be passed from person to person, as well as from cow to person. …and presumably, cow to cow. But the big question was about smallpox. So, Jenner infected the boy again, this time by injecting the smallpox pathogen into him.What?! And to his, the kid’s, and presumably the gardener’s great relief, he was immune. Just to be sure, Jenner then tested his methods on other neighborhood kids, including his own infant son! Eventually, the medical community and the general public accepted what Jenner had discovered: A “vaccine”. From the latin for “Cow”, “vacca”. In the end, Jenner made history. And luckily, no humans were maimed or killed in the process.It’s a good example of successful human medical experimentation. Other cases are more complicated. In fact: this case…kind of more complicated because if he had failed, he would’ve just been murdering people. But let’s look at the case of Alabaman doctor, J. Marion Sims. Originally lauded as the father of gynecology, history isn’t sure what to make of him now. In the mid-1800’s, Sims discovered how to operate on collapsed uteruses and how to close up fistulas, or tears in inner tissue suffered during childbirth. These were serious problems, that killed, or made miserable, many women at the time, and Sims pioneered the operation that fixes them.But, he tested his technique on slave women, often without anesthetic, even after such drugs became wildly available. He operated on one woman at least 30 times! Sad to say, the practices on human subjects didn’t improve much in the 20th century, when many doctors conducted their experiments on prisoners, poor folk, soldiers, and mental patients. Some of this work had good intentions, but some of it was just weird. Like back in 1920, when a resident physician in San Quentin prison in California, tried to revitalize older men by implanting them with the testicles from younger executed convicts, and even livestock! Whauuuuurgh! Of course, no one did evil experimentation quite like the Nazis, except maybe their equally morally bereft Japanese counterpart in the infamous Unit 731 secret research unit during World War II. I’ll let you research these atrocities if you want yourself, but suffice to say, there were many trials involving vivisections without anesthetic, forced sterilization, exposure to extreme temperatures, deadly pathogens and chemicals, and other, totally, TOTALLY messed up stuff. Today, it’s impossible to view any of these experiments as anything more than torture, thinly veiled as “medical research”.When the war ended, and the world learned what the Nazi researchers had done, the Nuremberg (Nrnberg) war trials began, and from them, we got the Nuremberg Code, a set of international rules outlined to protect human test subjects. The code? I know, revolutionary stuff! stated the the subjects voluntary consent, without coercion, is essential. Surprise! Really? Did us take THAT long to figure that out? Also, that the subject can end treatment at any time, that only licenced professionals should carry out treatments, and they should terminate the study if the subject is in danger. But – many US doctors believed that these rules only applied to war crimes, and apparently not their own research. So a booming prison population, combined with the rise of pharmaceutical and healthcare industries, led to tons of corporate and federally-funded experiments on prisoners. By the 1960s, at least half of states in the country allowed medical testing on prisoners, and about 90 % of pharmaceutical testing happened there.Meanwhile, some doctors would take their liberties outside of prisons, too. In 1963, Dr. Chester Southam injected cancer cells into around 20 elderly and infirm patients, at the Jewish Chronic Disease Hospital in Brooklyn, to see if their bodies would reject the cells the same way healthy bodies did. The patients were not asked for permission, they weren’t even told what was happening. Around that same time, word got out that researchers were infecting mentally disable children with viral hepatitis, at Staten Island’s Willowbrook institution, to test new treatments, Researchers found that the disease could be blocked with injections of the blood protein gamma globulin, but conditions were so inhumane that the institution was shut down.Hardly a shining victory for science. The final straw came in 1972, when news of the notorious 40-year-old Tuskegee experiment hit the press. The study began in 1932, when the public health service of Macon County, Alabama and the Tuskegee institute wanted to observe the effects of untreated syphilis. In exchange for free meals, medical exams and – burial services – nearly 400 poor syphilictic African-American men enrolled in the study and were told they were being treated for “bad blood”. They were NOT informed they had syphilis, they were never treated for it, even after Penecillin became a standard cure in 1947, and instead, the researchers observed how the disease progressed, and ultimately, KILLED over the years. Meanwhile, many of the men went home and inadvertently infected their families. Combined, these stories proved too much for the public, and the government got involved, By the mid-1970s, the U.S. banned all outside research in federal prisons, and cracked down on human subject experimentation. In response, many researcher outfits and drug companies simply moved their operations overseas. In 2008, the US department of health and human services estimated that as much as 65% of clinical trials of federally regulated drugs were done in foreign countries.Virtually none of those tests were closely monitored. Now, none of this is to say that a lot of good, live-saving treatments haven’t come out of human testing – virtually all of the big ones from blood transfusions to vaccines to organ replacement to space exploration, had to be tested on humans at some point. It’s just that experimenting on humans can be a slippery slope, and that’s why in recent decades some researchers have avoided the sticky wicket of experimentation on other people by experimenting on themselves. Bruce Banner style. The tradition of self-experimentation probably most famously began with the most amazing husband-and-wife team of Pierre and Marie Curie, who, in the early 1900s exposed themselves to lots, and lots, and LOTS of radiation while researching the elements they had discovered, Uranium and Radium. Pierre, for instance, strapped radium salts to his arm for several hours, then observed the resulting burn change over the course of several weeks. They were constantly sick, tired, and in pain, but the Curies’ research ushered in the use of radiation in medicine and earned both of them a Nobel Prize.And unfortunately, eventually killed Marie. Taking a cue from the Curies, decades later, in the mid-1980s, Australian doctor Barry Marshall and pathologist Robin Warren sought to refute the theory that stomach ulcers were caused by lifestyle factors like stress and poor diet. They believed, that the bacterium Helicobacter pylori was the culprit. To test this theory, Marshall decided to take one for the team. Fearing that the hospital’s ethics committee, and – his wife – would shoot his idea down if he asked, he just knocked back a petri dish and swallowed a healthy dose of the bacteria.4 days later, he started puking, and developed some serious death breath. Biopsies confirmed that the bacteria had taken up shop in his stomach and that he contracted gastritis, which eventually, may lead to ulcers. But the up factor eventually paid off. Marshall and Warren earned the 2005 Nobel Prize for medicine for their breakthrough contributions. And probably, a stern talking-to from Mrs. Marshall. Speaking of unhappy guts and self-testing, in 2004 Dr. David Pritchard strapped some Larva to his arm to infect himself with parasitic hookworms, to prove that the presence of these gut parasites significantly decreased the symptoms of auto-immune diseases. While doing field work in Papua New Guinea in the late 1980s, Pritchard noticed that natives infected with hookworms were largely unaffected by illnesses like Asthma, and seasonal allergies. He theorized that somehow, the worm switched off the immune system response and in the process, the immune system didn’t overreact with allergic symptoms. Before he could get an approval from regulators in Britain to recruit wheezy, sneezy volunteers, he used himself as the subject.And learned some important stuff: Turns out, 50 hookworms are too many and make you sick, but 10 is just the right amount to avoid intestinal discomfort an allergy symptoms. Soon, he had a steady stream of test subjects knocking on his door, inviting worms to get cozy in their intestines. Hopefully, in addition to learning more about our physical selves, we’ve also learned more about our moral selves. There will likely always be need for some level of human testing, a lab rat simply can’t stand in for everything. But researchers and regulators alike can take one very old piece of advice, because Hippocrates really did have it right: “Primum non nocere.” First, do no harm. Thank you for watching this episode of SciShow, if you have any questions, or comments, or ideas, you can leave them on Facebook or Twitter or down in the comments below and if you wanna keep getting smarter with us here on SciShow go to youtube.com/SciShow and subscribe. [SciShow outro music].