Even if science frequently saves lives, there are times when it commits heinous acts. Some are moral blunders, errors of judgment made by people who were confident they were acting morally. However, they can also be malevolent at times. Here are the ten most horrific human subject experiments in recorded history.

10. Surgery on Slave Women

J. Marion Sims, the originator of modern gynecology, became well-known for performing experimental procedures on slave women. Sims is still a controversial figure today because the women's illness he was treating caused excruciating pain.

Because the anesthetic had only recently been developed and Sims thought the procedures weren't "painful enough to merit the bother," he performed the surgeries without any anesthesia. There is an ongoing debate over whether Sims' patients would have agreed to the procedures if given a right to choose. 

9. The Aversion Project

The South African government upheld strict anti-homosexual legislation. In addition to being viewed as a deviant, homosexuality was seen as a manageable condition. Aversion therapy tactics were mainly applied to prisoners, and South Africans were compelled to enlist in the military under the period's conscription rules.

In Ward 22 at 1 Military Hospital in Voortrekkerhoogte, Pretoria, attempts were made to "cure" deemed deviants between 1969 and 1987. The victims were subsequently treated with hormone treatment, which sometimes involved chemical castration.

8. The Stanford Prison Experiment

The Stanford University emeritus professor of psychology Philip Zimbardo set out to investigate issues such as "What happens when you put decent people in horrible settings" in 1971. Thus, college students were hired to portray inmates and guards in the prison he constructed. After only six days, the two-week experiment had to be abandoned since things quickly became chaotic.

In barely a few days, guards turned cruel, and inmates displayed signs of great stress. The detainees were treated horribly by the guards almost right away. They stripped them naked, sprayed their bodies with delousing chemicals, and threatened and harassed them. The Stanford Prison Experiment was the foundation for psychologists' and even historians' knowledge of how even morally sound individuals might transform into such villains under particular conditions. 

7. The Tuskegee Study

For 40 years, the most well-known breach in medical ethics occurred in the United States. The U.S. Public Health Service began researching the consequences of untreated syphilis on black men's health in 1932, according to the Centers for Disease Control and Prevention.

Two hundred-one healthy males were studied, and 399 black men in Alabama who were being treated for "bad blood" were followed as the disease progressed. In actuality, the men received insufficient care, even in 1947, when penicillin replaced other drugs as the preferred syphilis therapy. According to the official Tuskegee website, authorities didn't shut down the study until a newspaper piece made it public in 1972.

6. The "Monster" Study

Speech pathologists at the University of Iowa began investigating the validity of their theory that stuttering was a learned behavior brought on by a child's fear of public speaking. Unfortunately, they tried to make orphans stutter by informing them they were destined to start stuttering in the future.

Thus, the researchers taught children at the Ohio Soldiers and Sailors Orphans' Home that they were stuttering and should only talk if they were sure they would speak correctly. Although the experiment did not cause stuttering, it did drive children to become withdrawn, apprehensive, and silent.

5. Triplets Separation 

Clinical psychologists under the direction of Peter Neubauer conducted a covert experiment in the 1960s and 1970s in which they separated twins and triplets from one another and adopted them out as singletons. Three identical triplet brothers were unintentionally reunited in 1980, leading to the discovery of an experiment allegedly partially funded by the National Institute of Mental Health. 

One of the triplets, David Kellman, expressed resentment toward the experiment: "We were robbed of twenty years together," he claimed. His brother Edward Galland committed suicide in 1995 at his Maplewood, New Jersey, home. The study's co-directors, child psychiatrists Peter Neubauer and Viola Bernard, exhibited no remorse. Furthermore, they even claimed they were doing the children a favor by separating them so they could grow as unique individuals.

4. Stanley Milgram's Shock Experiments

The shock experiments by Peter Wenkman in the "Ghostbusters" movie were clearly inspired by what happened in the 1960s. Americans who volunteered for a Yale study believed it was about memory and learning. They were instructed to act as "teachers" in Milgram's studies, reading lists of words to "learners." Each person playing the part of the teacher was given instructions to depress a lever that would shock their "learner" each time he failed a word-matching quiz. 

About two-thirds of the teachers shocked students at the greatest possible voltage, continuing to administer jolts as directed by the experimenter. Teachers believed that the voltage of shocks increased with each mistake and ranged from 15 to 450 possible volts. In actuality, this wasn't a test of memory or learning but instead of our willingness to submit to authority. Luckily, no shocks were delivered.

3. CIA Mind Control Experiments

The CIA began looking into ways to transform Americans into CIA-controlled "superagents," people who could carry out murders. Additionally, they wouldn't submit to enemy interrogations during the Cold War. Researchers from the CIA conducted experiments on unwitting Americans (and Canadians) as part of the MK-ULTRA project.

One of the techniques is to sneak them psychedelic chemicals like LSD, PCP, and barbiturates. Other unlawful methods included hypnosis and possibly chemical, biological, and radioactive weapons. Universities collaborated without their awareness, primarily as a delivery system. The U.S. Department of Veterans Affairs claims that 7,000 troops are believed to have participated in the study against their will.

2. Unit 731

The Japanese Imperial Army tested civilians for medical and biological purposes during the 1930s and 1940s, mainly in China. The death toll of these cruel trials, overseen by General Shiro Ishii, the head doctor of UNIT 731, is unknown. Unofficially, 200,000 people perished.

Many illnesses were investigated to see whether they could be used as weapons of war. They included cholera, typhoid, typhoid paratyphoid, dysentery, anthrax, and plague. Numerous atrocities followed, including the transmission of plague-carrying fleas throughout Chinese cities, cholera, and typhoid infection of wells. Prisoners were allegedly given poison gas doses, placed in pressure chambers until their eyeballs popped out, and even dissected while still alive and aware, according to former unit members who spoke to media outlets.

1. Nazi Experiments by Jozef Mengele 

During the Holocaust, Josef Mengele, an SS doctor, performed some of the most notoriously horrific experiments at Auschwitz. Mengele searched the inbound trains for twins to experiment on to support his views about the Aryan race's superiority. In the process, many people died. The U.S. Holocaust Memorial Museum claims that he also collected the eyes of his deceased "patients."

Infectious disease and chemical warfare therapies were tested on prisoners by the Nazis. According to the Jewish Virtual Library, some people were compelled to undergo aviation tests in low-pressure and frigid environments. Additionally, numerous inmates underwent experimental sterilizing techniques. The majority of doctors performing these atrocities were processed. However, Dr. Mengele died as a free man in Brazil.

The law requiring informed consent for any government-funded medical study involving human subjects was passed by the United States Congress in 1974. However, before 1974, the ethics surrounding the use of humans in research experiments were a little lax. Hence, there are a lot of inhuman experiments that put great shame on medicine and humanity as a whole. 

What's the worst human experiment story you've heard? Which experiments would you add to the list?

Cover photo: Michael Jasmund/Unsplash