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Ape and Essence: The Stoned Ape Hypothesis

The Leaf investigates the theory that psychedelics played a role in early primates’ ascendance to higher consciousness.

Illustration by Outside Artwork

The internet is both a blessing and a social curse. However, one of its better contributions to society is that it has kept the spirit of late ethnobotanist and psychedelic pundit Terence McKenna alive. Though he died in April of 2000, McKenna’s ideas and philosophies still soar through the interwebs, thanks to Reddit, podcasts and numerous social media platforms. One theory in particular that has continued to gain steam is the so-called “Stoned Ape Hypothesis.” 

It all started in 1992 when McKenna broke the world’s collective brain with his book “Food of the Gods: The Search for the Original Tree of Knowledge: A Radical History of Plants, Drugs, and Human Evolution.” In it, he proposed a radical evolutionary theory: that psilocybin mushrooms were responsible for catalyzing our evolution from Homo Erectus into Homo Sapiens. In other words, our bodies and brains function as they do today because our ancestors tripped out on psychedelic mushrooms. The psychoactive effects of these mushrooms, he argued, essentially reorganized the information processing center of the primitive primate brain – sparking the evolution of consciousness, cognition and language – by prompting hominids to engage in experiences like community, spirituality and self-reflection. Psilocybin, McKenna wrote, brought us “out of the animal mind and into the world of articulated speech and imagination.” This theory would eventually come to be known as the Stoned Ape Hypothesis (though McKenna himself never actually used that term). 

Since its publication, people haven’t stopped talking about the Stoned Ape Hypothesis – despite the fact that traditional scientists have consistently dismissed it as “simplistic” and nothing more than a “high thought” (albeit the most elaborate high thought ever, articulated in over 300 pages). But recent developments in psychedelic science have greatly expanded what we know about the impact of entheogens (particularly psychedelic fungi) on the brain, and some believe these new findings bolster the validity of the theory.

“When Terrence wrote [Food of the Gods], most people dismissed it, saying he’s a crazy druggie trying to come out with this idea,” said Terence’s younger brother Dennis McKenna (who helped him shape the theory) on the “Conversation with Kais” podcast last year. “Some of the more thoughtful critics said it was plausible, but now because of the discoveries about [mushrooms’ impact on] neurogenesis, epigenetics and neuroplasticity, Stoned Ape has gone from plausible to probable.”

McKenna was undoubtedly a man ahead of his time. Unlike today, he didn’t have a library of scientific research to cite showing that psychedelic mushrooms stimulate the growth of new neurons, reorganize synaptic connections or impact gene expression – concepts on which the Stoned Ape Hypothesis is essentially predicated. Anthropological evidence indicates that the brain size of Homo Erectus roughly doubled between 2 million and 700,000 years ago. What’s more, it’s estimated that the brain volume of Homo Sapiens grew three times larger between 500,000 and 100,000 years ago. Though mainstream scientists remain flummoxed about how and why this occurred, the Stoned Ape Hypothesis offers a potential answer.

“The fossil remains we’ve found show that hominids and cattle lived in the same environment,” Dennis McKenna explains. “If you have these two elements in the ecology – especially cattle, because where there are cows, there’s cow shit – mushrooms had to be there. There is no fossil evidence showing this because mushrooms don’t hold up well, but mushrooms grow on cow dung. If you go to any similar ecology in modern times – tropical pastures with cattle – the world over, you will find these mushrooms.”

A state of consciousness (according to science) is an effect of receiving and processing information through multiple qualitative experiences, including sensations and feelings, the nuances of sensory qualities, and cognitive processes (i.e., evaluative thinking and memory). Essentially, our hominid ancestors’ warm, almost tropical environments allowed for a symbiotic trifecta between cattle, mushrooms and people – theoretically creating the ideal conditions for exponential brain growth and the emergence of such consciousness. While we still don’t fully understand the nature of consciousness or how it evolved, scientists generally agree that it was more complicated than simply eating psychedelic mushrooms. 

Consequently, many Stoned Ape haters scoff at the simplicity of the McKenna theory – such as paleontologist Martin Lockley, Ph.D., who explained to Inverse in 2017 that the Stoned Ape Hypothesis hinges on consciousness sprouting from a singular source. But the McKennas never actually claimed that mushrooms were the sole cause for the rise of consciousness; in fact, Dennis has publicly stated that the media has oversimplified the theory and that he believes psilocybin mushrooms were only a factor in the emergence of consciousness and the mind – a sort of evolutionary catalyst.

“It’s not so simple to say that [hominids] ate psilocybin mushrooms and suddenly the brain mutated,” he explains in the film “Fantastic Fungi.” “I think it’s more complex than that, but I think [mushrooms] were a factor. It was like software to program neurologically modern hardware to think, have cognition, and to have language.”

While most scientists get hung up on this single-source-for-consciousness notion, there are some who agree with the McKennas. While admitting that the Stoned Ape Hypothesis is technically unprovable, iconic mycologist Paul Stamets nevertheless advocates for it.

“I suggest to you that Dennis and Terence were right on,” Stamets proclaimed in the keynote address he gave at the 2017 Psychedelic Science conference entitled “Psilocybin Mushrooms and the Mycology of Consciousness.” “I want you or anyone listening, or seeing this, to suspend your disbelief,” he advised. “I think this is a very, very plausible hypothesis for the sudden evolution of Homo Sapiens from our primate relatives.” Apparently, the crowd agreed – as evidenced by the roaring ovation they can be seen giving him in the YouTube video of the discussion.

Regardless of what modern science says, anyone who’s done a deep dive into the mushroom realm understands how the Stoned Ape Hypothesis could be true. And if there’s one nugget of wisdom we can take away from this discussion, it’s that humans have always been fascinated with psychedelics – particularly when it comes to the existential ponderings of how we got here and the story of humankind.

“If I could sum it up, I would say the mushrooms taught us how to think,” Dennis McKenna asserts. “They gave us the tools of the imagination, and from that, everything else proceeds.” 

Photos by @outsideartwork

This article was originally published in the August issue of All Magazines.

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