The stoned ape theory is a controversial hypothesis first proposed by American ethnobotanist and mystic Terence McKenna in his 1992 book Food of the Gods.
McKenna's argument has largely been ignored by the scientific community,[4] who cite numerous alleged discrepancies within his theory and claim that his conclusions were arrived at via a fundamental misunderstanding of Fischer's studies.
He believed that psilocybin mushrooms were the "evolutionary catalyst" from which language, projective imagination, the arts, religion, philosophy, science, and all of human culture sprang.
To support his claim, McKenna used studies from the Hungarian-American psychopharmacologist Roland L. Fischer dating back to the 1960s and 1970s to underline the purported effects psychedelics would have had on mankind.
McKenna claimed that minor doses of psilocybin improve visual acuity, including edge detection, which bettered the hunting skills of early primates and thus resulted in greater food supply and reproduction.