Evolution is a rock-solid scientific theory, as strong as theories come. It explains the extreme diversity of the organisms present on this world. It is supported by mountains of scientific data, most importantly molecular biology and the fossil record. However, now and again, apparent anomalies appear in the fossil record which baffle even those most familiar with biology and evolution.
From the evolution of the first Homo species, Homo habilis, to Homo sapien, the human brain size doubled more than doubled (from 612cc to 1000-1900cc*), in a period of almost 2 million years (an incredibly small amount of time on the evolutionary timeline). There is much debate on how this managed to happen, considering that this is the fastest, largest growth of any organ in the entire fossil record. The late Terence Mckenna provides an intriguing answer to this biological phenomenon. He offers the Stoned Ape Theory, which I would like to familiarize you with.
Mushrooms and Human Evolution
As our ape ancestors were driven from rainforests to grassy plains due to climatic change and our incapability to safely use fire, their diets changed. While foraging for food on these newly inhabited grasslands, they began to encounter psilocybin containing mushrooms, and this symbiosis made its mark on human evolution in several ways.
“Psilocybin is a naturally occurring psychedelic compound produced by more than 200 species of mushrooms . . . As a prodrug, psilocybin is quickly converted by the body to psilocin, which has mind-altering effects similar to those of LSD and mescaline . . . The effects generally include euphoria, visual and mental hallucinations, changes in perception, a distorted sense of time, and spiritual experiences, and can include possible adverse reactions such as nausea and panic attacks.”*
Psilocybin had three immediate effects on grazing Homo habilis.
- Visual Acuity: Visual acuity and edge-detection are, as Mckenna states, the “first level” of psilocybin effects. Visual acuity was a remarkable advantage for the hunter-gatherer communities.
- Sexual Arousal: Psilocybin acts as a nervous system stimulant, and thus instances of copulation naturally increase din our restless ancestors. This helped to naturally select individuals who consumed psilocybin-containing mushrooms.
- Spiritual Enlightenment: Mckenna’s third level of psilocybin effects is full shamanic ecstasy. He proposed that high doses of psilocybin caused some spiritual enlightenment in tribal groups, promoting social responsibility and oneness.
Mckenna also noted psilocybin’s tendency to facilitate linguistic thinking and communication. Primates under the effects of psilocybin would have been inclined to begin vocalization, which would produce vibrations that cleanse the brain of impurities and cause genetic diversity.* Once speciated into Homo sapiens, the species began to migrate from Africa to colonize the rest of the world.
The Stoned Ape theory is interesting but not foolproof, and this post only scratches the surface when it comes to human evolution. You can find more information on the Stoned Ape Theory for yourself by reading Terence Mckenna’s book, Food of the Gods.
OTB Awaken Your Imagination

Is this for discussion? If so -
True as you say (accuracy points): McKenna did allege scientists reported psilocybin (“in small doses”) enhances visual acuity. But – what if the scientists he named (Fischer & Hill) refute his claim about their work? If no ‘enhanced visual acuity’ is actually reported in the studies McKenna cited for it (easily verified by just reading) – what might one reasonably conclude about a ‘theory’ based thereupon?
Suppose McKenna stoned apes ‘theory’ was not just screwy speculation (not theory), based on deliberate fabrication?
What if, beyond making up his ‘data,’ McKenna even bragged about it? Like when he told Gracie & Zukov (interview) he wrote FOOD OF THE GODS as “consciously propaganda”? Would it be a factor for his theorizing?
Further into the rabbit hold – suppose for McKenna fans, what’s true or not doesn’t even matter? What if they cheered his fraud as a public service announcement (i.e. endorsement certain things they approve, like tripping)?
Hypothetically: suppose McKenna wrote FOOD as a ploy, calling it his ‘trojan horse’ to be left at academia’s gates – tricked out with ‘impossible-to-find’ citations; to dupe whoever to think its nonfiction, scholarship? (its on internet) …
If that were the case, how would it affect the ‘interest’ stoned apes holds – as a ‘theory’ (not a pretense or fraud)? What difference if any would it make if McKenna based his ‘theory story’ on false ‘facts’ – to then speculate from?
What if stoned apes, held up to light – proved transparent as a cheap lace curtain: a piece of hokey evolution pseudoscience? Like a faux-psychedelic version of “Scientific” Creationism? But switching out Bible for FOOD O’ GODS, and pushing psychedelics rather than communion wafer?
If a close look at it revealed stoned apes to be a fake theory, built on falsified testimony – a tissue of deception, with a particular covert Modus Operandi – would it matter? If so, how exactly?
Visual acuity … eye wonder.
I have to agree with you. McKenna was not a scholar and his work should not be treated as such. I definitely agree that many young mushroom enthusiasts use his work as a way to justify their actions, not that that is necessarily a bad thing.
I haven’t looked into any of McKenna’s sources myself, but after reading the book I can say that some of his conclusions are a bit of a stretch. Still, it’s an interesting read.
Thanks for the thoughtful comment, MR.