11 Shocking Science Experiments That History Books Don’t Talk About

WARNING: This post discusses the disturbing treatment of adults, children, babies, and animals.

1.In 1931, psychologist Winthrop Kellogg and his wife Luella tried to answer a bold question: Is it nature or nurture that makes us human? To find out, they decided to raise their infant son, Donald, alongside a baby chimpanzee named Gua — as siblings. I know…this sounds like an ’80s sitcom, but they literally brought a chimp into their home and started treating her like a second child. The idea was to see whether Gua could learn human behaviors and maybe even develop language. For months, they fed them together, dressed them the same, and treated them as equals. At first, Gua was more advanced — walking, understanding commands, and even solving problems faster. But then something unexpected happened. Instead of Gua becoming more human, Donald started grunting like a chimp and copying Gua’s behavior. Alarmed, the Kelloggs ended the experiment after just nine months — fearing that their son’s development might’ve been permanently altered.

The experiment was interesting, sure, but it’s now seen as wildly unethical. There was no informed consent (obviously — Donald was a baby), and the risks to the child’s cognitive and emotional development were huge.

It’s hard to say what the effects on Donald were. He grew up to be a physicist but died by suicide in his early 40s. Gua, meanwhile, was sent back to a primate center, where she died of pneumonia less than a year later.

(Note: the above image is not of Donald and Goa, but some other kid/chimp combo from the ’50s. What was going on back then, lol?)

2.If you thought the first story was the worst thing an experiment could do to a baby, you’d be wrong. In 1920, psychologist John B. Watson wanted to prove that human emotions were learned, not innate. To do that, he used a 9-month-old orphan known only as “Little Albert.” At first, Albert loved animals and played happily with a white lab rat. But then the experiment began. Every time Albert reached for the rat, researchers loudly smashed a steel bar with a hammer behind his head. The goal? To condition him to fear the rat. Soon Albert cried just at the sight of the animal. He also became terrified of rabbits, dogs, and even cotton balls. Basically, anything fluffy (like the rat). The experiment ended — but Albert’s trauma didn’t. Watson never deconditioned him.

For years, no one knew what happened to Little Albert. Then, in 2009, researchers discovered he died at age 6. He may have had underlying neurological issues, raising even more concerns about the ethics of the study. Talk about heartbreaking…and beyond messed up.

3.Unit 731 was a secret Japanese military unit responsible for some of the worst atrocities in human history. Operating during WWII in occupied China, Unit 731 was set up by the Imperial Japanese Army to develop biological and chemical weapons. But what they really did was unleash a reign of medical terror. Prisoners — men, women, children, and pregnant women — were subjected to live vivisections (yes, cut open without anesthesia), frostbite testing (limbs frozen and smashed with sticks), and deliberate infection with diseases like plague, cholera, syphilis, and anthrax. Victims were even dissected alive just to see how the organs reacted in real time. It’s estimated that at least 3,000 people died inside Unit 731.

And if you’re thinking, Yay! A messed-up experiment not involving Americans! Well, I have bad news for you: In a disgraceful move, the U.S. government gave immunity to the unit’s top scientists after the war in exchange for their research.

4.In the ’50s, psychologist Harry Harlow ran experiments using baby monkeys that showed they preferred soft, comforting “mothers” (a cloth doll) over wire ones that just provided food. He presented the results under the title “The Nature of Love”, and contended that love and affection were essential to development. You’re probably thinking: What’s this doing on the list? Harlow’s experiments sound sweet! And they would’ve been…if he’d stopped there. But in a follow-up experiment, Harlow built a device he literally called “The Pit of Despair” — a steel isolation chamber where baby monkeys were placed alone, in total darkness, with no contact for weeks or months. The results were devastating. The monkeys emerged catatonic, rocking back and forth, unable to interact with others. Some refused food, curled into balls, and eventually died from sheer despair. Others became violent or socially dysfunctional.

How did Harlow go from studying “The Nature of Love” to “The Pit of Despair”? Well, he had a major depressive episode in 1968 that landed him in a mental hospital, and he hoped to find a cure for depression by studying the effects of isolation and depression. His colleagues, however, were horrified. One of his collaborators later called the studies “the most unjustifiable experiment I’ve ever seen.”

5.In apartheid-era South Africa, being gay wasn’t just socially unacceptable; it was treated like a disease, and the military took it upon itself to “cure” it. Between the late 1970s and mid-1980s, under a program dubbed The Aversion Project, the South African Defence Force subjected hundreds of conscripted soldiers suspected of being gay or transgender to forced psychiatric “treatment.” And by treatment, we mean electric shock therapy, chemical castration, and, in some cases, involuntary gender-reassignment surgeries — all done without the patient’s consent. Doctors and military psychologists, led by a man named Dr. Aubrey Levin, implemented these so-called therapies in secret. Victims were often teenagers and young men. The goal? “Re-orient” their sexual behavior by associating same-sex attraction with pain. Like, hook-you-up-to-a-machine-and-show-you-erotic-photos-while-shocking-you pain.

When the truth came out in the 1990s, it horrified human rights organizations around the world. The total number of victims is unknown, but estimates range from a few hundred to over a thousand — and numerous men subjected to this died by suicide during or after taking part in the project.

Adding to the horror? Dr. Levin later moved to Canada…where, in 2013, he was convicted of sexually assaulting male patients.

6.In 1939, researchers at the University of Iowa, led by speech pathologist Wendell Johnson, conducted what’s now known as the “Monster Study.” Why? Because it was so cruel, even those who ran it regretted it. Johnson — himself a stutterer — wanted to test whether stuttering was learned or inherited, and hypothesized that if you harshly criticized a normal child enough, you could give them a speech disorder. So, they took 22 orphans and split them into two groups. One group received positive, supportive, and encouraging speech therapy. The other group was treated like garbage. Every time they spoke, they were told they were stuttering — even if they weren’t. The therapists interrupted them, scolded them, and picked apart their speech until the kids became self-conscious, anxious, and withdrawn. Some developed real speech issues, while others became too scared to talk.

The whole thing was kept secret for decades — and only came to light in the early 2000s when journalists uncovered it. In 2001, Iowa issued a public apology to the surviving participants. Six years later, they settled a lawsuit filed by the victims for $925,000. The victims’ lawyer said at the time of the filing, ”I think that a jury will agree that even if these people’s speech wasn’t exactly ruined, their lives were. Kathryn Meacham (one of the victims) has thought of herself as a freak all her life. She still hates to talk, except to her family and a few people in her church. She’s a sad, sad lady.”

7.I was going to say that this one is horrifying as a parent, but you don’t need to be a parent for it to make you sick to your stomach. In the 1950s, American and British scientists literally collected body parts from dead children — without their parents’ knowledge — to study. The U.S. Atomic Energy Commission was worried about the effects of nuclear fallout (specifically radioactive isotopes like Strontium-90, a byproduct of nuclear weapons tests), so, since these particles collect in bones, they wanted to find out how much radiation was accumulating in human tissue — particularly in children, whose bones absorb it more rapidly. The solution? Set up a secret project (creepily dubbed Project Sunshine) where they could analyze bones, especially from infants and young children, to monitor radiation exposure across different regions. The catch? No one told the families.

Doctors and pathologists in the U.K., Australia, and Canada harvested samples from deceased children and infants — often just the legs or long bones — and shipped them to the U.S. for testing. Parents were told their child’s remains had been buried intact, or in some cases, not told anything at all.  In Wales, one couple was unable to dress their baby for her funeral because her leg bones had been removed for Project Sunshine.

The government later admitted that over 1,500 samples from dead babies and young children were used without consent. The scandal came to light in the late 1990s, prompting public outrage and a formal apology from the U.K. government. Un-fucking-believable.

8.Imagine going to the doctor for treatment — only to find out 40 years later they were intentionally letting you suffer for research. That’s what happened to 399 Black men in Tuskegee, Alabama, starting in 1932. The U.S. Public Health Service told them they were receiving free medical care for “bad blood,” a term that loosely meant any number of ailments. In reality? The men (who were unaware they had syphilis) were enrolled in a study to observe the long-term effects of untreated syphilis. The men weren’t told they had syphilis, nor were they treated for it — even after penicillin became widely available in the 1940s. And they weren’t allowed to quit the study. Doctors allowed the disease to ravage their bodies — causing blindness, brain damage, and death — just to see what would happen. It wasn’t until 1972, when a whistleblower leaked the story, that the study was finally shut down. By then, 128 men had died.

Above, 94-year-old Herman Shaw, a survivor of the Tuskegee Syphilis Study, speaks at the White House in 1997. At the event, President Clinton formally apologized to the survivors and families of the victims.

9.In the ’60s, Yale psychologist Stanley Milgram ran an experiment to test how far people would go in obeying authority, even when it meant hurting someone. Spoiler alert: people are messed-up lemmings. Volunteers were asked to act as the “teacher,” delivering electric shocks to a “learner” (who was actually an actor) every time they got an answer wrong. The shocks weren’t real, but the participant didn’t know that. The voltage labels? “Slight Shock” all the way up to “XXX — Danger: Severe Shock.” With each wrong answer, the participant was instructed to turn up the voltage. As the shocks escalated, the actor screamed, begged for mercy, banged on the wall, and eventually went silent. But if the volunteer hesitated, the researcher — calmly and firmly — told them to continue. Disturbingly, most participants kept going. In fact, 65% went all the way to the highest voltage, believing they’d electrocuted a stranger into unconsciousness.

The study sparked massive ethical backlash because — well, duh — it was manipulative and traumatizing (some participants suffered intense guilt after realizing what they’d done). But others saw it as a chilling and necessary window into how things like the Holocaust could happen.

10.In the summer of 1971, psychologist Philip Zimbardo set out to study how power and authority affect human behavior, so he and his team converted the basement of Stanford University’s psychology building into a mock prison. They recruited 24 male college students and randomly assigned them to play either guards or prisoners. It was supposed to last two weeks…it didn’t make it past six days. Almost immediately, the “guards” — wearing khaki uniforms, mirrored sunglasses, and holding batons — began to abuse their power. They insulted, humiliated, and punished the “prisoners,” who were forced to wear smocks, ID numbers, and stocking caps. The “prisoners” grew withdrawn, anxious, and depressed. Some even suffered emotional breakdowns.

One participant went on a hunger strike. The guards responded by forcing him into solitary confinement — a dark closet — and making the other prisoners chant in support of the punishment. Zimbardo, playing the role of prison superintendent, didn’t intervene. In fact, he later admitted he got so caught up in the simulation he didn’t realize how bad it had gotten. It wasn’t until a fellow psychologist (and Zimbardo’s then-girlfriend) came to visit and was horrified by what she saw that he agreed to shut it down.

Was the Stanford Prison Experiment unethical? (Yes.) Was it even scientific? (That’s debatable — some claim the guards were coached to act harshly.)  A 2015 movie, The Stanford Prison Experiment, told the story onscreen.

11.And lastly, it’d be impossible to write about the most horrific scientific experiments ever without discussing the Nazi regime, which forced thousands of unwilling people — mostly Jews, Romani people, and prisoners of war — to be test subjects in unbelievably horrific experiments. Doctors at concentration camps like Auschwitz and Dachau froze victims alive to test how long the body could survive hypothermia, forced people to ingest seawater, and deliberately infected others with diseases like malaria and tuberculosis, all without anesthesia or consent. One of the most infamous figures was Dr. Josef Mengele — known as the “Angel of Death” — who had a particular obsession with twins, often performing surgeries on one twin and then killing the other to compare the organs. His “research” also included injecting dye into children’s eyes to try changing their color and sewing twins together to create artificial conjoined siblings.

None of these experiments produced any medically useful data. Most were sadistic, pseudoscientific, and fatal. After the war, the Nuremberg Trials exposed these atrocities, leading to the creation of the Nuremberg Code — a set of ethical principles for human experimentation that still guides modern medical ethics (or at least is supposed to, anyway).