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The True Story of Dr. Voronoff’s Plan to Use Monkey Testicles to Make Us Immortal

For Dr. Voronoff, all it took to create immortal giants were some monkey testicles and imagination. (Image: Filip em/Wikipedia)

The search for a Fountain of Youth has driven humankind down some strange avenues of inquiry. But there may be none stranger than the work of Dr. Serge Voronoff. Known in his time as “the monkey gland expert,” Voronoff believed that human aging could be halted or even reversed by transplanting monkey testicles into people. And that was among the most down-to-earth of his ideas.

The doctor was born in Russia in 1866, and moved to France at the age of 18, becoming a citizen in 1895. While there, he studied under Alexis Carrel, a surgery and transplant pioneer who won a Nobel Prize for his work on sewing blood vessels. Through his studies with Carrel, Voronoff became fascinated with the possibilities of animal-to-human transplants that he believed could restore youthful vigor and even cure diseases via a transfer of hormones.

In 1889, Voronoff began working with experimental physiologist Charles-Édouard Brown-Séquard, who was also interested in the rejuvenating effects of animal glands. Brown-Séquard began experimenting on himself that very same year, injecting his body with a serum containing crushed up matter from the testicles of guinea pigs and dogs. Unfortunately, the “Brown-Séquard Elixir” failed to produce any miraculous results, other than Brown-Séquard’s anecdotal benefits. The publicly ridiculed experiment (in a 1907 article in The Ellensburgh Capital, it was unfavorably compared to Ponce de Leon’s hunt for a mythical Fountain of Youth), led Voronoff to conclude that tissue grafts were the only way to reap the benefits of animal fortitude.  

A political cartoon of Voronoff in performing an appendectomy in Egypt

A political cartoon of Voronoff performing an appendectomy in Egypt. (Image: Wellcome Images/Wikipedia)

In 1896, Voronoff moved to Egypt, turning his eye to eunuchs. According to a 2007 paper on Voronoff’s life and work, “[h]e noted their obesity, lack of body hair, and broad pelvises, as well as their flaccid muscles, lethargic movements, memory problems, and lowered intelligence.” All of this deficiency he blamed on their lack of testicles—a loss he assumed robbed the eunuchs of magical glandular excretions.

After spending 14 years working and researching in an Egyptian hospital, Voronoff returned to France in 1910 to continue his experiments. He returned to working on animals, transplanting organs, tissue, and bone between animal species, working with the “open-minded” Collège de France. He made a name for himself thanks to his work trying to improve beasts of burden like horses and sheep by implanting testicular tissue from younger animals onto older ones. During his experiments, he came to the idea that the higher simians were the perfect donors for humans because they shared all the necessary biological similarities required for transplant, with the benefit of monkeys’ stronger constitution. Voronoff implanted a chimpanzee thyroid gland into a young French “idiot” in 1915, and claimed that over the next year, his mental faculties returned to normal.    

The young boy Voronoff implanted with a chimpanzee thyroid gland.

The young boy Voronoff implanted with a chimpanzee thyroid gland. (Image: Jreferee/Wikipedia)

In particular Voronoff again focused on the power and impact of the sexual organs, specifically the testicles. In his 1920 book, Life; a Study of the Means of Restoring Vital Energy and Prolonging Life, Voronoff says, “The sex gland stimulates cerebral activity as well as muscular energy and amorous passion. It pours into the stream of the blood a species of vital fluid which restores the energy of all the cells, and spreads happiness.” To Voronoff, the process of taking healthy sexual gland tissue, such as bits of monkey testicle, and sewing onto the testicles of aging humans, was to inject the body with youth itself.

Dr. Voronoff’s first monkey-testicle-to-man-testicle xenograft occurred in July of 1920. He is said to have taken a small scrap of young monkey testicle just a few centimeters wide and a few millimeters thin, and sewn it right into the patient’s scrotum. Voronoff contested that the procedure could do everything from return youthful energy to curing senility and schizophrenia to radically prolonging life. An increase in sexual ability was also of course implied, and tended to become the focus of interest in his work, despite Voronoff’s repeated assertions that any romantic improvements were just a side-effect of a transformation that was healing the patient’s entire being, a process he called “rejuvenation.”

A comparison photo of a man before and after Voronoff's "rejuvenation."

A comparison photo of a man before and after Voronoff’s “rejuvenation.” (Image: Wellcome Images/Wikipedia)

By 1923, Voronoff was the director of the experimental laboratory at the Collège de France, and his testicular grafts had gained such popularity and acclaim that a special reserve was being set-up in Africa specifically to capture and maintain monkeys for gland transfer. He presented his procedure to the thousands-strong International Congress of Surgeons in London, wowing the assembly with his seemingly ground-breaking solution to aging (and, ideally, impotence). At the conference he also touted that his procedures would soon be available to women as well, and promised to turn “grandmothers into debutantes.” Voronoff’s enthusiasm for shoving monkey testicles into the human body was both ambitious and infectious. By the mid-1920s, at least 300 people had undergone his procedure, including at least one woman receiving a xenograft of monkey ovary.

The demand for Voronoff’s procedure continued to increase, as did his ambition. Following in the mold of any classic mad scientist, Voronoff bought himself a castle in Grimaldi, Italy in 1925. Citing the prohibitive costs and hassle of transporting monkey parts for his procedures, Voronoff built a primate enclosure in the garden and hired a former circus trainer to manage his new farm. Castle Voronoff was also outfitted with a small hospital where the doctor could perform the grafts.

Castle Grimaldi

Castle Voronoff (Image: Bella28/Wikipedia)

In a 1927 article printed in the Delaware Star, Voronoff claimed that his procedure had been performed over 1,000 times throughout the world, restoring septuagenarians to the strength of their youth. Even more startlingly, Voronoff said that he had begun administering the rejuvenating testicle grafts to young sheep, essentially creating a race of super-sheep. Voronoff claimed the resulting animals showed increased size and strength. He notes that while such a radical procedure had not been attempted on a human, it would likely result in a giant ubermensch with increased size, strength, and lifespan. He even hints at immortality, stating that in theory, a human could live for as long as he could keep his gland healthy.

While some found the concept of the miracle graft as insane as we might today, Voronoff was able to charge as much as 10,000 francs for the surgery—a year’s salary for a chorus member at the Paris Opera during the 1920s. He was fiercely serious about his work, not wanting to be seen as a sideshow, or as he put it in 1927, to be “Barnumized.” Voronoff would also branch out into other questionable experiments including transplanting a human ovary into a monkey, (unsuccessfully) attempting to impregnate the animal with human sperm, and trying to lock down the testicles of death row criminals to see if their grafted tissue would impart any of their “perverse” traits to other human donors.

As those who had undergone the procedure aged, the chorus of skeptics grew. The benefits that Voronoff claimed to be seeing would disappear after around three-to-five years, a problem he explained away as the gland dying off, but which could be fixed by a subsequent transplant. By 1930, Voronoff was theorizing that he needed to better match the blood of the monkey and the patient, and suggested a single procedure would let people live to 140. The scientific community was less than convinced.

Another patient of Voronoff's rejuvenation.

Another patient of Voronoff’s rejuvenation. (Image: Wellcome Images/Wikipedia)

Some of the complaints were as silly as the procedure itself, like the accusation that rejuvenated people or their children would start devolving into primate behavior, while others, such as the discovery of testosterone, first isolated in 1935, were a bit more damning. Voronoff’s procedure had always hinged on the mysterious glandular secretions that he was simply convinced were there. As testosterone was discovered and its purposes explored, his vigors and rejuvenations began to feel pretty silly.

Voronoff quit performing the procedures around 1930, but continued to proselytize the benefits of his xenografts, while performing research on curing human ailments—which he refused to name—at Castle Voronoff. When World War II broke out, Voronoff was in the United States, escaping the Nazis, although he was called back to France in 1939 to act as a surgeon. After the war, Voronoff returned to his castle to find it had been decimated by bombing, but he was determined to rebuild it. Alas, Voronoff died in 1951, wealthy but discredited, never having been rejuvenated himself, despite multiple declarations that he would, should the need ever arrive.

Between 1920 and 1940, some 2000 monkey-man testicle rejuvenations were administered everywhere from France to India and beyond. In the modern view, the procedure seems somewhat ridiculous, but his legacy as a real-life, balls-to-the-wall mad scientist is truly enthralling.