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Key points
- The stoned ape theory posits that magic mushrooms played a major role in the evolution of human consciousness.
- More likely theories hold that humans' ability to justify themselves drove consciousness and culture.
- Social intelligence, technological capabilities, and propositional language make human consciousness distinct.
Is the “stoned ape theory” of human consciousness valid? This is the hypothesis that consuming psychedelic mushrooms played a major role in the evolution of human consciousness. It was put forth by Terence McKenna in Food of the Gods: The Search for the Original Tree of Knowledge, and favorably mentioned by Joe Rogan.
Recently a published study wove some interesting puzzle pieces together to suggest that McKenna's speculation might have had some merit. The study was picked up by Popular Mechanics and other news outlets with announcements like, “Scientists say they may have discovered origin of consciousness”!
As a scientist, let me tell you that headlines like these are irresponsible. Is it possible that consuming magic mushrooms played a role in the evolution of human consciousness? Of course. Many things are possible. However, it is not terribly plausible, nor is it clear how this would have happened. McKenna tells an interesting story, but that is pretty much all we are looking at. As such, it is a weak evolutionary idea, one that is entertaining and could have some validity but is probably more misleading than useful. The recent study lends some weak support to it, but not much. As is so often the case, the problem is much more in the headlines than the study.
How Do We Define Human Consciousness?
Before we even consider something like the stoned ape theory, we need to back up and get clear about what know about human consciousness and how it is distinct from other animals and how it likely evolved. Failure to do this results in confusion about what one is trying to explain. For example, animals like dogs obviously have consciousness in the sense that they have inner experiences and feel pain. Making this point makes it obvious that we are not trying to explain subjective conscious experience, and that the emphasis is more on "human" than on "consciousness" per se. And it makes it clear that it is absurd that the stoned ape theory is about the "origin of consciousness" as the headline proclaims.
What are the elements that make human intelligence and consciousness distinct? There are three major domains: a) our social intelligence; b) our technological capacities; and c) propositional language. Michael Tomasello, along with many other researchers, has documented that humans have excellent capacities to develop a “we” space. That is, we can quickly determine the intentions of others, and we can develop shared attention. This means that humans can network together in activities like hunting.
It also means we are more likely to develop collective activities, like engaging in dance. Hunting and dancing require tools in the form of weapons and instruments, and humans demonstrate a remarkable capacity to evolve technology. This has been especially the case in the last 100,000 years. It is the central driver in the evolution of civilizations, which is becoming ever more apparent with our invention of AI.
Last, humans have propositional language. To be sure, other animals have rich capacities for communication. Elephants, killer whales, dolphins, and other great apes can be argued to show the basic elements of symbolic communication. However, humans have an open, symbolic, syntactical language; put more simply, humans talk via propositional language (i.e., in sentences).
What happened was that there was a tipping point from broken symbolic language into propositions. Concretely, this is the difference between going from “antelope…there” to “There are the antelope.” This is crucial because propositions carry what is called "positive meaning" because they make a truth or value claim. These assertions can then be challenged. How? With questions, such as who, what, when, how, and the most crucial “why.”
The fact that we can question the validity of propositions results in a massively complex problem. What truth and value claims should a group or individual adopt? This "question-answer dynamic" is called the problem of justification. Ultimately, it means that humans need to justify themselves at the individual and group level.
The Justification Hypothesis
The idea that propositional language created the adaptive problem of justification is called the Justification Hypothesis (Henriques, 2003). Notice that it is clear, logical, and not only possible, but clearly plausible, almost to the point of being logically inevitable. However, at this stage in the argument, it remains a hypothesis because we have not given any evidence for it. To do so, we can ask: If it were the case that humans were confronted with this core problem of justification several hundred thousand years ago, then what follows from it?
The answer is that we should see design features in human consciousness that have been shaped by the problem of justification. In addition, we should also see it in human culture. When we turn to our lives, we can then see immediately that this is true (Henriques, 2011; Shaffer, 2005; Quackenbush, 2005). Humans constantly are justifying themselves to themselves and to others. And human cultures can be framed as being tied together by systems of justification. We can also see that this is true in what scientific psychology has revealed about human consciousness and social processes.
Justification Systems Theory (Henriques & Michalski, 2019) ties these ideas together and explains why human consciousness is different from consciousness in other animals. Indeed, please try to doubt it. Raise the question that it might be something else, and see what happens to your consciousness. You will find yourself in a stream of justification. Why? Because human nature comes with a mental organ of justification (Henriques, 2003).
Finally, we can see this visually. Justification Systems Theory is part of a larger system, called UTOK, the Unified Theory of Knowledge (Henriques, 2022), which gives us a unified framework for natural science, human consciousness, and the collective wisdom traditions. Here is UTOK’s Tree of Knowledge System (Henriques, 2003; Henriques and Volk, 2023).
The red layer is the Mind-Animal plane. The blue is the Culture-Person plane. Some time between 500,000 and 50,000 years ago, our ancestors developed the capacity for propositional language, resulting in the problem of justification. That in turn drove human consciousness and culture, which is a whole new plane of existence. Justification Systems Theory is the theory that explains how we go from minded animals to cultured persons.
You are a cultured person who justifies your actions on the social stage. That is what makes human consciousness unique, and the central event was when propositional language gave rise to question-answer dynamics and the adaptive problem of justification. And the theory has been scientifically known for more than two decades. We just need to look at the updated, scientifically informed Tree of Knowledge to see it.
References
Henriques, G. (2022). A new synthesis for solving the problem of psychology: Addressing the Enlightenment Gap. Palgrave MacMillan.
Henriques, G. R. (2011). A new unified theory of psychology. New York: Springer.
Henriques, G. R. (2003). The tree of knowledge system and the theoretical unification of psychology. Review of General Psychology, 7, 150-182.
Henriques, G. R. & Michalski, J. (2019). Defining behavior and its relationship to the science of psychology. Integrative Psychological and Behavioral Science 54(1), 1-26.
Henriques, G, & Volk, T. (2023). Toward a Big History 2.0. The Journal of Big History, 6(3), pp. 1-4.
Quackenbush, S. (2005). Remythologizing culture: Narrativity, justification, and the politics of personalization. Journal of Clinical Psychology. 61
Shaffer LS. (2005). From mirror self-recognition to the looking-glass self: exploring the Justification Hypothesis. J Clin Psychol. 2005 Jan;61(1):47-65
