I once seen an excellent documentary about the intelligence of dogs. Part of it was about a breeding experiment with foxes, which took some decades though I'm not sure how long. Basically, they bred the foxes which were the most tame and after a while they became equivalent to dogs, their coats got lighter also...

So Terence McKenna is known for hypothesising that apes may have gained human consciousness through incorporation of psilocybin mushrooms into their diets.

Observation of apes on psilocybin mushrooms could help validate the hypothesis? More so, breeding apes which use the mushrooms? Injecting psilocybin would not do... it would have to be ingestion by choice, or suggestion so that it can be seen whether they would actively choose to use shrooms again and so they can mentally identify the cause and effect.

I'm well aware there are moral issues here... but filling in this piece in the puzzle of evolution is a worthy cause, or at least crossing out this quite convincing idea as an option.

Also briefly thought that insects would be better because they breed so fast. Then again, not sure about insect metabolism of tryptamines, and don't like the idea of intelligent insects xD

Thoughts?

I have thought about this and it certainly does raise some ethical issues, but let's ignore those for the moment. It would take a very long time to perform this kind of experiment. This is why studies of evolution are generally done with microbes or insects; huge populations and many generations can be handled in relatively little time. However, these organisms lack certain precursory elements. You would need a relatively intelligent animal. To actually test the hypothesis you would, of course, need an ape, but I am interested in the possibility of other organisms, namely octopi.

Even if the effects of psilocybin on psychological development were proven, the Stoned Ape hypothesis would still be up in the air because you would have to prove not only that it was possible, but that it actually occurred in our history.

I can prove the stoned ape theory right now...

... by lighting this fat bowl of Grand Daddy Purple

Hey, Nexians, GREAT idea! All willing participants in this evolutionary trial can RACE.

Let's see who reaches the next stage of evolution first! *flicks lighter*

I can't conceive of anything that would give us a clear enough answer within one lifetime...

^^^
You can always do it Bene Gesserit style and carry it through the generations.

It would be very expensive, but to economize time one could use huge populations of apes, breed them at sexual maturity, then kill, sell, or release them. Repeat with subsequent generations. Keep the the ones that display higher intelligence for examination and reproduction. Of course, you would want a control group as well to see not only if psilocybin is a cause, but perhaps just a catalyst.

I've pondered this hypothesis too. I find it very acceptable.

I wonder if you could test it on intelligent animals.
What if you gave a domesticated parret psilocybin-in-water every once in a while?
Would it's cognitive, social & lingual abilities evolve faster and evolve beyond average?

I wonder how well chimps can learn if they drank some mushroom tea every once in a while.

It's trickier then that. Showing that psilocybin makes an animal smarter would be huge but it would have little bearing on the evolutionary hypothesis. The hypothesis is that the stoned apes changed their breeding behavior such that the 'smartest' or best at language had a reproductive advantage. This leads to an increase in intelligence and an increase in language sophistication in the population.

Like bluevelvet said, doing experimental population genetics on apes is not feasible because their generation time is similar to human. So the experiment could take hundreds of thousands of years.

There is an easier way though. First we must establish how some population of apes does mating selection. Lets assume that this selection is done violently. (not a bad assumption in general for primates.) In other words, the toughest, most badass violent male ape breeds with the most females. This is our baseline.

Now we introduce psilocybin and see if the mate selection changes significantly. I suppose the hypothesis would predict that mate selection would no longer be a violent process. Rather, the smartest and/or most communicative apes would breed more then the old-style violent ones. Over time these tendencies would accumulate in the population even in the absence of psilocybin. This would provide support for the hypothesis.

Alternatively, and more likely IMO, most of the stoned apes would be terrified and confused except for a small fraction of the original population. This fraction would still have the presence of mind to breed. This would also effect the structure of the population over generational time but I'm not sure it speaks directly to McKenna's original hypothesis.

Don't forget McKenna's three stages:

Threshold effects [+]: heightened visual acuity, particularly edge detection, aids in hard survival
Sub-hallucinatory [++]: Sexual stimulation encourages reproduction
Effective dose [+++(+)]: Shamanic ecstasy, spiritual rites (this is, of course, an even higher stage, more in the realm of social evolution)

The first two aforementioned effects of psilocybin affect very base biological factors in nature. These factors and those of language, cognition, etc. would be integral according to McKenna's hypothesis and therefore extremely difficult to deconstruct.