
The stoned ape theory is a controversial hypothesis first proposed by American
ethnobotanist
Ethnobotany is an interdisciplinary field at the interface of natural and social sciences that studies the relationships between humans and plants. It focuses on traditional knowledge of how plants are used, managed, and perceived in human societi ...
and
mystic Terence McKenna
Terence Kemp McKenna (November 16, 1946–April 3, 2000) was an American ethnobotanist and mystic who advocated for the responsible use of naturally occurring psychedelic plants and mushrooms. He spoke and wrote about a variety of subjects, ...
in his 1992 book ''
Food of the Gods''.
The idea claims that the
cognitive revolution
The cognitive revolution was an intellectual movement that began in the 1950s as an interdisciplinary study of the mind and its processes, from which emerged a new field known as cognitive science. The preexisting relevant fields were psychology, ...
was caused by the addition of
psilocybin mushroom
Psilocybin mushrooms, or psilocybin-containing mushrooms, commonly known as magic mushrooms or as shrooms, are a type of hallucinogenic mushroom and a polyphyletic informal group of fungi that contain the prodrug psilocybin, which turns into t ...
s, specifically the mushroom ''
Psilocybe cubensis
''Psilocybe cubensis'', commonly known as the magic mushroom, shroom, golden halo, golden teacher, cube, or gold cap, is a species of psilocybin mushroom of moderate potency whose principal Psychoactive compound, active compounds are psilocybin ...
,'' into the human diet
around 100,000 years ago. Using evidence largely based on studies from
Roland L. Fischer et al. from the 1960s and 1970s, he attributed much of the mental strides made by humans during the cognitive revolution to the effects of psilocybin intake found by Fischer.
McKenna's argument has largely been ignored by the scientific community, who cite numerous alleged discrepancies within his theory and claim that his conclusions were arrived at via a fundamental misunderstanding of Fischer's studies. McKenna's theory was not based on
scientific evidence
Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical ev ...
.
Overview
In his book, McKenna argued that due to
desertification
Desertification is a type of gradual land degradation of Soil fertility, fertile land into arid desert due to a combination of natural processes and human activities.
The immediate cause of desertification is the loss of most vegetation. This i ...
in
Africa
Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
, humans retreated to the shrinking tropical forests, following
cattle
Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...
herds whose dung attracted the
insects
Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...
that he states were certainly a part of the human diet at the time. According to his hypothesis, humans would have detected ''
Psilocybe cubensis
''Psilocybe cubensis'', commonly known as the magic mushroom, shroom, golden halo, golden teacher, cube, or gold cap, is a species of psilocybin mushroom of moderate potency whose principal Psychoactive compound, active compounds are psilocybin ...
'' from this due to it often growing in
cowpats.
According to McKenna, access to and
ingestion
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms, inge ...
of mushrooms was an
evolutionary
Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certa ...
advantage to humans'
omnivorous
An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...
hunter-gatherer
A hunter-gatherer or forager is a human living in a community, or according to an ancestrally derived Lifestyle, lifestyle, in which most or all food is obtained by foraging, that is, by gathering food from local naturally occurring sources, esp ...
ancestors
An ancestor, also known as a forefather, fore-elder, or a forebear, is a parent or ( recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from w ...
,
also providing humanity's first religious impulse. 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.
Evidence
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
Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
improve visual acuity, including edge detection, which bettered the
hunting
Hunting is the Human activity, human practice of seeking, pursuing, capturing, and killing wildlife or feral animals. The most common reasons for humans to hunt are to obtain the animal's body for meat and useful animal products (fur/hide (sk ...
skills of early
primate
Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...
s and thus resulted in greater food supply and reproduction. At higher doses, McKenna contended that the mushrooms would increase
libido
In psychology, libido (; ) is psychic drive or energy, usually conceived of as sexual in nature, but sometimes conceived of as including other forms of desire. The term ''libido'' was originally developed by Sigmund Freud, the pioneering origin ...
, attention, and energy, resulting in greater reproductive success. At even higher doses, the psilocybin would promote greater social bonding within early human communities as well as group sex activities, resulting in greater
genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
from the mixing of
genes
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
. McKenna also theorized that at this level of psilocybin intake, it would trigger activity in "language-forming region of the brain", resulting in the mental development of
visions and
music
Music is the arrangement of sound to create some combination of Musical form, form, harmony, melody, rhythm, or otherwise Musical expression, expressive content. Music is generally agreed to be a cultural universal that is present in all hum ...
and kickstarting the development of
language
Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing syste ...
by enriching their troop signals. According to McKenna, psilocybin would also chip away at internal
ego and make religious matters the forefront of the mind.
Variations

Some who hold that the use of drugs played a pivotal role in human development argue that it was not psilocybin that initiated greater cognitive development amongst humans, but was instead spurred by other psychedelics such as
DMT-containing substances, in particular,
Ayahuasca
AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...
. Ayahuasca has been shown to increase trait openness significantly by one standard deviation.
Additionally, it has shown to increase interest in abstract ideas and visual acuity when consumed. This has led to it being hypothesized that some sort of DMT-containing substance was the culprit behind the cognitive revolution.
However, psilocin, the active product of psilocybin metabolism, is 4-hydroxy DMT and oral ayahuasca has nearly identical pharmacology and pharmacokinetics as ingesting psilocybin mushrooms.
Reception
The stoned ape theory had been widely criticized by the greater scientific community. McKenna's theory was labeled as overly speculative by much of the academic community and misrepresenting the studies of
psychopharmacologist Roland L. Fischer, whose research was frequently cited by McKenna as evidence for the purported effects of the mushrooms on early humans. Additionally, many pointed to groups such as the
Aztecs
The Aztecs ( ) were a Mesoamerican civilization that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the ...
or various
Amazonian tribes whose usage of
psychedelic substances does not reflect any of the evolutionary advantages that McKenna argued would emerge from using psilocybin-containing substances.
See also
*
Aquatic ape theory
*
Evolutionary models of human drug use
*
Psilocybin
Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
*
Psilocybin mushroom
Psilocybin mushrooms, or psilocybin-containing mushrooms, commonly known as magic mushrooms or as shrooms, are a type of hallucinogenic mushroom and a polyphyletic informal group of fungi that contain the prodrug psilocybin, which turns into t ...
*
Drunken monkey hypothesis
References
{{reflist
1992 introductions
Human evolution
Theories
Psilocybin