In this Wired video, David Hibbett, a mycologist at Clark University, demystifies the world of mushrooms by answering questions asked about them by the internet. Of course, no mushroom discussion would be complete without touching on the topic of "magic" mushrooms. His answer to "Why did mushrooms evolve to have psychedelic properties?" is actually really interesting:
You shouldn't assume that magic mushrooms evolved to have hallucinogenic properties for the benefit of humans. In fact, magic mushrooms probably don't care about humans at all.
Lots of fungi and plants for that matter produce chemicals whose primary function is to deter grazers.
In the case of psilocybin mushrooms, I've heard an idea suggested recently, that psilocybin may actually interfere with the digestion of slugs. Slugs are major grazers on mushrooms.
So if that is true, then it is just a happy accident of evolution that we can get high feeding on what is essentially slug poison.
SLUG POISON!
