What is the Stoned Ape Theory?

March 16, 2023

In 1992, the famed late ethnobotanist, psychonaut, and mycologist Terrence McKenna released his seminal work, Food of the Gods. Within the books’ 300+ pages, McKenna explored humankinds’ fascination with altered states of consciousness, its unique relationship with psychoactive plants, fungi, and other substances, and argued that hallucinogens played a major role in the evolution of Homo sapiens.

Among the many ideas presented in the book, the “Stoned Ape Theory” has seemingly stood the test of time best, not because there’s been any general scientific acceptance of the concept but because of its fascinating, mind-bending, history-changing story.

Humankind’s Primordial Trip

The fundamental hypothesis behind the Stoned Ape Theory is that the unexplained explosive growth in Homo sapiens’ brains — in a three million year period, the human brain grew from 350 grams to 1,350 grams, quadrupling the size its predecessors had attained over the previous 60 million years of evolution —was caused in part by our ancestor’s ingestion of psilocybin-containing mushrooms.

But this wasn’t some one off trip. Rather, it’s posited that our ancestors regularly ate psilocybin-containing mushrooms during the Pleistocene epoch, a tumultuous time for the earth’s climate stretching from 2.6 million to 11,700 years ago. Desertification of the African continent was occurring during this time, causing our ancestors to migrate from the shrinking tropical canopy in search of food. As they migrated, it’s believed that these bands of Homos followed herds of cows and other herbivores, munching on the flies that accompanied these animals, flies that enjoyed buzzing around cow poop.

Inevitably, the theory goes, Homos came into contact with Psilocybe cubensis, a psychedelic, cow dung-loving mushroom, that’s the most common psilocybin-containing mushroom in today’s world. Being in a new land amid a new lifestyle with novel food sources, experimentation and hunger were likely. Naturally then, Homos ate Psilocybe cubensis.

That’s the first part of the theory. But McKenna took it even further.

Using his psychedelic experiences and research as a jumping off point, McKenna posited that this new fungal-human interaction and the resulting consciousness-altering experiences were foundational to modern day civilization.

McKenna believed different dosages could have helped Homo sapiens develop new ideas and perspectives.

At low doses, psilocybin would have improved visual acuity, helping those who ate the mushrooms become better hunters and in turn reproduce at higher rates. At medium doses, the mushrooms would have increased sexual arousal, further increasing the rates of reproduction.

And at high doses, ego dissolution would occur, promoting community bonding and group sex, which thereby created greater genetic diversity. Further, high doses would lead to transcendent experiences, thereby creating a need or desire for something akin to religion to try and explain the strangeness of the experience. High doses would also cause communication between areas of the brain that are typically separate, as well as synesthesia, the blending or crossing of senses (e.g. the sensation of seeing sounds or tasting colors).

As Terrence’s brother, Dennis McKenna, put it in the documentary Fantastic Fungi:

“It’s not so simple to say that they ate psilocybin mushrooms and suddenly the brain mutated. I think it’s more complex than that, but I think it was a factor. It [psilocybe cubensis] was like a software to program this neurologically modern hardware to think, to have cognition, to have language—because language is essentially synesthesia. Language is the association with apparently meaningless sound except that it’s associated with the complex of meaning.”

Today, the Stoned Ape Theory continues to enlighten, entertain, and attempt to explain our ancestor’s evolution and relationship with psychedelic mushrooms. And though scientists have never truly given the theory any serious consideration, you can count one scientist, mycology guru Paul Stamets, as a Stoned Ape theory backer.

“What is really important for you to understand is that there was a sudden doubling of the human brain 200,000 years ago,” Stamets said at the 2017 Psychedelic Science conference, when he offered support for the theory. “From an evolutionary point of view, that’s an extraordinary expansion. And there is no explanation for this sudden increase in the human brain.”

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