I've held this theory on my own after experiencing geometric shapes while hallucinating after smoking a lot of marijuana years back. I sat down closed my eyes and experienced an intense feeling of flying through what I can only explain as the starfield screen saver from Windows but with colored 2D shapes heavily dominated by hexagons of various sizes. During that experience I realized that I might be experiencing the…
I've mentioned this before on HN, but I don't understand why SAH is seen as a "solid" theory. Psychedelics might increase some cognitive or perceptual faculties, but McKenna never gives any physical mechanics for how this could possibly lead to genetic alteration, i.e. how it creates any selection pressure for intelligence.
If you raise a dog in complete social isolation (not even human contact) it will be unable to cope in the outside world. The same applies to people, if a baby is raised with no interaction, they will not be capable of functioning as a normal human. There's a very well written, Pulitzer Prize winning article on one such case in Florida: http://www.tampabay.com/projects/girl-in-the-window/danielle...
I think that a convincing argument could be made that psychedelics could work to kick-start this mental expansion. There are plenty of stories of people suddenly being able to understand complex abstract concepts after using psychedelic drugs.
That's not to say that I believe that the Stoned Ape Hypothesis is "solid", I haven't done any research into it to be able to make that judgement, but it is plausible.