The stoned ape theory, or stoned ape hypothesis, proposes that early hominins ate psilocybin mushrooms and that the effects helped produce larger brains, language and self-awareness. Terence McKenna set it out in Food of the Gods, published by Bantam Books in 1992 (Open Library record).
A 2021 paper summarises his claims: that psilocybin sharpened vision, raised sexual activity and fostered visionary experience, and that it drove a rapid reorganisation of the brain (Rodríguez Arce and Winkelman, 2021). The same authors, who think psychedelics may have played some role, call a simple one-cause version “most certainly false” and say direct evidence of early humans eating these mushrooms is lacking.
Other evidence fits poorly with a sudden change. A 2018 analysis found that hominin brain size grew mostly gradually (Du et al., 2018). Lab studies of psilocybin describe altered perception, not sharper vision. Rival ideas, such as cooking, also compete for the same ground. Nobody has tested whether eating these mushrooms changed how many descendants anyone left, which natural selection would require. So the theory is best described as untested, with its simplest form not supported.
Sources
- Food of the Gods (McKenna, 1992), Open Library record
- Rodríguez Arce and Winkelman, 2021, Frontiers in Psychology
- Du et al., 2018, Proceedings of the Royal Society B
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