Sourcing evidence from prehistoric times is notoriously difficult. What we do know (or think we know, to be more accurate) is often pieced together from archeological finds and correlations of semi-related "facts" from various scientific fields, forming a theoretical model of "how things used to be". We do not know how accurate our models are (each person has their own).
> low doses of psilocybin improve visual acuity, particularly edge detection, meaning that the presence of psilocybin in the diet of early pack hunting primates caused the individuals who were consuming psilocybin mushrooms to be better hunters than those who were not, resulting in an increased food supply and in turn a higher rate of reproductive success.
> Then at slightly higher doses, he contended, the mushroom acts to sexually arouse, leading to a higher level of attention, more energy in the organism, and potential erection in the males, rendering it even more evolutionarily beneficial, as it would result in more offspring.
> At even higher doses, McKenna proposed that the mushroom would have acted to "dissolve boundaries," promoting community bonding and group sexual activities.
> At these higher doses, McKenna also argued that psilocybin would be triggering activity in the "language-forming region of the brain", manifesting as music and visions, thus catalyzing the emergence of language in early hominids by expanding "their arboreally evolved repertoire of troop signals."
I'm not saying we don't have evidence for what happened in prehistoric times. As you said, that's hard. But the above is the outline of Mckenna's theory, taken from wikipedia. My point, is that he makes a number of claims as to the effects of psilocybin - see above - and none of those claims of what the drug can do are backed up by evidence.
I assume that Mckenna may have been speaking from personal experience, that the drug improves visual acuity and can sexually arouse, but there's no evidence for it.
I always thought he was putting way more emphasis on the "visual acuity" part than it deserved, maybe he was grasping for something from the material science world to be able to include.
> that the drug improves visual acuity and can sexually arouse, but there's no evidence for it.
If you're referring to formal, peer reviewed studies, of course not. But the sexual arousal and community bonding aspects I'd say there's plenty of anecdotal information consistent with the possibility. This of course in no way proves that his theory has any validity to it on a historic basis, but it at least doesn't rule it out as being impossible.
The whole theory is best taken with a healthy quantity of salt (and it's best to listen to audio of it), but it is a really interesting theory/prediction. One's opinion of the plausibility is likely proportional to their experience with psychedelics, those with a lack of experience would likely have some difficulty with the "how" part.
> I'm not saying we don't have evidence for what happened in prehistoric times. As you said, that's hard. But the above is the outline of Mckenna's theory, taken from wikipedia. My point, is that he makes a number of claims as to the effects of psilocybin - see above - and none of those claims of what the drug can do are backed up by evidence.
So, what you're saying is that it's state-of-the-art work in the burgeoning field of evolutionary psychology.
No. I'm saying that the effects of psilocybin claimed by Mckenna, and which are required for his theory, do not exist. Specifically, for example, psilocybin actually reduces vision, rather than improving it [1] : which invalidates Mckennas first quoted point above.
