Here’s what you’ll learn when you read this story:

• Russian zoologist Ilia Ivanov was determined to find a way to hybridize humans and chimps, and successful hybridization of other animals convinced him it was possible.
• After Ivanov was able to implant a human ovary in a female chimp, he unsuccessfully tried to inseminate her with human sperm, so he went in the opposite direction.
• Ivanov imported chimps to Russia, inseminating unpaid Soviet women with their sperm, though none conceived because human and chimp chromosomes are incompatible.

Towards the end of Planet of the Apes, a shirtless Charlton Heston kisses chimpanzee doctor Zira (an uncharacteristically hairy Kim Hunter) as waves crash against the shore in the background. She cringes and protests that he is so “ugly.” Just as in this fictional scene, chimps have no desire to mate with humans in the real world, either. But that didn’t stop one early 20th-century scientist from going even further than Charlton Heston did.

Zoologist Ilia Ivanov was the Soviet researcher who proverbially flew too close to the sun when it came to the fantasy of a human-ape hybrid. Around the turn of the century, he conducted experiments that involved artificially inseminating horses to create superior offspring for Imperial Russia, and this work earned him recognition from the Bolsheviks. Ivanov wasn’t satisfied with merely enhancing a species, though. Hybridization became his obsession, and he was soon crossing zebras with donkeys, cows with bison, and several different species of rodents with each other. In 1910, he brashly declared he could see a human-ape hybrid in the future.

During an era of political upheaval, Ivanov was able to gain government backing for his hybridization program. He set off for French Guinea in 1925. After heading back to Moscow for more funds and then returning to the town of Kindia in western Guinea in 1926, he received approval from the African colony’s French governor and ventured into the jungle to wrangle chimps, which were notoriously difficult to catch. He heard rumors that male chimps had attempted to breed with local women, who were then ostracized. While this seemed highly unlikely, he proceeded with his experiments despite being unable to inseminate locals with chimp sperm. He decided to instead use human sperm to inseminate female chimps. Unsatisfied, he considered inseminating local women without their consent, since he dismissed their fears as “primitive.”

Even the Kremlin was horrified at Ivanov’s plan. Forbidden from anything nonconsensual, he nevertheless continued with his experiments during the same period that witnessed the infamous Scopes “Monkey Trial”, which made headlines in 1925 when a Tennessee teacher was arrested and tried for teaching evolution. Ivanov was unfazed even when he faced a wave of sensationalism after catching the attention of the Western press. In a 2008 study titled “Beyond Eugenics: The Forgotten Scandal of Hybridizing Humans and Apes,” historian and cultural scientist Alexander Etkind explored the efforts Ivanov made to merge humans with chimps, along with the possible social and ethical implications of his work.

“The public wanted either irresistible proof of the theory that men originate from apes or irrevocable evidence that the proponents of this theory commit unspeakable sins,” Etkind said. “Curiously, Ivanov’s project seemed to promise final arguments to both of these camps.”

This attention ironically secured American backers for Ivanov. There were high expectations after Ivanov and surgeon Sergei Voronov successful implanted a human ovary into a chimp named Nora in Guinea. Nora was then inseminated with human sperm but never conceived. Ivanov still made the journey from Guinea to to Moscow with twenty chimps, and the four chimps who survived were brought to his newly built “Primatological Nursery” in the Soviet republic of Abkhazia. In this subtropical paradise, under the guise of the Russian Institute of Experimental Endocrinology and subsidized by the Communist Academy, Ivanov attempted to inseminate unpaid Soviet women with sperm from his chimps, but none became pregnant.

There is no natural way for an ape to impregnate a human or vice versa, because there is a mismatch in gametes. Great apes have 48 chromosomes. Humans only have 46. This incompatibility was an obstacle that Ivanov could not get past, and his supporters were growing impatient. There was a new delivery of chimps to the nursery in 1930, but in the light of questionable ethics and zero progress, Ivanov was arrested and exiled to Kazakhstan, where he died two years later. Some of the apes and monkeys that outlived him were launched into space with the Sputnik missions during the 1960s.

Ivanov possibly had darker motives while embodying the “Red Frankenstein” he became known as. Though his experiments were supposedly an attempt to prove the genetic relationship between humans and great apes, there was also thought to be an anti-religious side to the project, spawned from a Soviet atheism tainted by racism. There was already an existing theory that different races of humans are each derived from particular ape species. Proposals for future hybridization attempts involved merging humans from different backgrounds with apes to produce offspring that would, not unlike Aldous Huxley’s tiers of genetically engineered citizens in Brave New World, range from more apelike people to an idealized vision of Homo sapiens. Evolution would be in human hands.

That departing scene in Planet of the Apes might have a deeper message in this historical context. Humans and chimps may share ancestors who interbred, but they grew too genetically distant to produce hybrid offspring. Maybe Heston’s beached astronaut would look hideous to a female chimp for a perfectly good reason. Some ideas, no matter how daring, should never leave the realm of science fiction.