Upvoted you because I find it humorous that so many go off the defensive deep end with regard to your little joke. My own opinion regarding the matter is that

Upvoted you because I find it humorous that so many go off the defensive deep end with regard to your little joke. My own opinion regarding the matter is that there are plenty of mind and body altering effects that we encounter every day. I'm a chemical engineer, and anyone who is involved with chemistry or biology can tell you that all but the simplest mechanisms are difficult to understand. There can be repercussions you would never predict from some compound. Heck, even ordinary food items (high fructose corn syrup, margarine) are constantly under debate because of the unknown long-term effects. With a system as complex as the human body, it's difficult to tell what subtle effects may exist. But you can't avoid it. As a whole, people are living longer and healthier than they were in the past (well, maybe that second point is debatable in some countries). I think the best philosophy is to weigh the risks and go with what you ultimately think will be the best route for yourself. Someone who has terminal cancer may be willing to try a new drug that isn't well understood at all, but that's because the possible benefits far outweigh any risk. So it comes down to an individual decision of what you find to be an acceptable risk. And I think it should be a right to make personal decisions like that. For me personally, I'm not going to try illegal drugs because I believe they have a higher probability of causing negative long term effects. Do they actually? Who knows; you could debate this ad nauseum. And science isn't anywhere near a stage to definitively confirm or refute it. But it's not a risk I'm interested in taking. In fact, I find it funny that out of all the unconventional things that Feynman tried in his life, the thing that embarrassed him was the time he tried LSD (he was worried about any unknown effects it might have on his brain).