Dr. Leo Stanley and the San Quentin Eugenics Experiments

San Quentin State Prison

San Quentin State Prison

Medical science has taken humanity down some very strange paths during its long history. From cures that involved cannibalism to an attempt to measure the weight of the soul at the beginning of the last century, doctors–those sober, respectable people we trust with our lives and health–can sometimes have more in common with the fictional Dr. Frankenstein.

One such doctor turned mad scientist was Dr. Leo Stanley. Serving as San Quentin’s chief surgeon for the better part of forty years, he played a big role in modernizing the infamous prison’s medical facilities. While this was undoubtedly good for prisoners, the good doctor’s research took darker, more unethical turns during his years at the prison. His research focused on eugenics, a now infamous pseudoscience that posits that humans can be bred via artificial selection to function better in society. The most extreme version of eugenics was practiced by Nazi Germany, who killed millions during the Holocaust in an attempt to rid the world of those they believed were racially undesirable.

Dr. Stanley did not want to exterminate those who he felt were undesirable. Instead, he focused on rejuvenating their masculinity through two bizarre methods: sterilization, and by implanting them with “testicular substances” from executed prisoners or, in some cases, livestock.


Rejuvenation and sterilization

While it might seem strange today to implant another person’s–or an animal’s for that matter–testicles into a human being, the procedure had become something of a fad in the early 20th century. The practice was known as rejuvenation, the idea being that an aging man could have his masculinity renewed by having the testicles of a younger man implanted into him.

Teasing out just how a quack cure like rejuvenation has anything to do with eugenics takes a little lateral thinking. Dr. Stanley–who was not coincidentally an aging middle class white man–obsessed over the plight of white masculinity in a country increasingly inhabited by a melting pot of races and ethnicities. He believed that the decline of white, masculine vigor would lead to a degrading of the moral values of the country. To put it bluntly, he was afraid that “undesirables” would reproduce faster than “good” people (which naturally meant white Christian people in the racial thinking of the time) and flood society with their bad genes. By reinvigorating aging white men, and by sterilizing more people with less desirable traits, Dr. Stanley believed that violence in society could be reduced.

While involuntary sterilization was legal in California, and in many parts of the country at the time, the amount allowed in prisons was limited. Dr. Stanley found a workaround to this by asking for volunteers for what he called “asexualization.” He advertised it as a procedure that would increase their “general health and vigor,” and that it would increase their libidos to boot. By 1940, 600 prisoners had volunteered to be sterilized. Some did so simply because they did not want more children. others believed the notion that the procedure would improve their health, while others feared that they might father children who were as bad as themselves.



Image from the Eugenics Congress of 1920.

Bizarre experiments

The sterilization program at least fit in with the idea of stopping the spread of “undesirable” genes. Rejuvenation fit into the scheme in a twofold way. First, if the practice could be proven to actually work, it might be something that could become more available to the broader society. the prison gave Dr. Stanley a controlled setting with lots of male test subjects with which to develop proof of concept. Second, Dr. Stanley and others at the time believed that disease and malfunction of endocrine glands might play a part in criminal behavior. So, while Dr. Stanley did no want the prisoners reproducing, he still felt that by revitalizing their masculinity they might be reformed.

He began the rejuvenation experiments in 1918, five years after taking the post at San Quentin. He grafted testicles from executed prisoners into old, senile prisoners. Over time, the supply of human testicles could not keep up with experimental demand, and he began to source the glands from goats, boars, and deer. These surgeries were meant to correct the imbalance of the prisoner’s glands and thus correct their behavior.

When the “donors” moved from humans to animals, Dr. Stanley changed the procedure from implanting the glands to smashing them into a kind of slurry, which was injected into the patient’s abdomen just under the skin. Patients reported an increase in energy and health, although how much of that was psychological and how much actually resulted from the treatment itself is anyone’s guess. Many prisoners volunteered for the procedure; prison society is hyper-masculine, and any way to improve one’s physical strength and manliness was welcome in such a society. When World War II came around, volunteering for medical experiments gave prisoners a way to feel like they were helping a bigger cause.

Dr. Stanley did his part for the war as well, serving as a surgeon for the Navy in the Pacific. He returned to San Quentin after the war, and found that the institution had undergone a shift in thinking, away from the more biologically driven ideas of yesteryear toward psychological treatment. The sterilizations dropped to a trickle, and the rejuvenation experiments dropped to nothing.

Stanley retired in 1951 and took a position as a doctor aboard a cruise ship. He himself underwent a vasectomy, apparently believing his own hype about their benefits. He died in 1976 at the age of 90. It is interesting to note that despite his beliefs in eugenics and his fear that inferior stock would take over the human population, Dr. Stanley never had any children of his own.



Blue, Ethan. “The Strange Career of Leo Stanley: Remaking Manhood and Medicine at San Quentin State Penitentiary, 1913-1951.” Academia.edu. Accessed May 3, 2014.