The reason why I don't like drugs: if they are so beneficial, why doesn't the body produce them by itself? It seems to me evolution would have figured out a way to do that by now. If it hasn't, maybe there are some side effects that diminish fitness. Same goes for genetic engineering, I remember the story about the memory gene for mice - if all it takes for a better memory is to flip one gene, surely evolution would have managed to do that a long time ago.
Of course evolution might have another "idea" of what is good for us than we do (evolution doesn't really care about us).
"The reason why I don't like drugs: if they are so beneficial, why doesn't the body produce them by itself? It seems to me evolution would have figured out a way to do that by now. If it hasn't, maybe there are some side effects that diminish fitness."
You are forgetting the other side to evolutionary fitness: the environment. Human evolution has been progressively stagnated by the invention of adaptive technology. Being hard of hearing or nearly blind is no longer a deadly condition, hence it no longer prevents procreation, hence evolution doesn't factor anymore.
The human genetic structure is largely the same as it was hundreds if not thousands of years ago precisely because we can use tools to adapt to situations much faster than any evolutionary fitness can proof out and spread through the population.
As for the memory gene of mice, that would only have been important if a better memory made mice more successful at what they do. Evidently in the environments mice adapted to this was not the case.
"Of course evolution might have another "idea" of what is good for us than we do (evolution doesn't really care about us)."
Evolution doesn't have ideas. It does not use reason. It does not think. It exists purely as a pattern of change in species over time. There is no need to give it more credit than that, it is quite powerful enough without the addition of sentience.
The body doesn't produce certain drugs because they have nothing to with our survival. Even if we don't need them, certain drugs can give you a decided competitive advantage over your peers. Of course, you have to be willing to put something in your brain that alters it in a way that no one truly understands. I'm sure it is prudent to err on the side of caution when it comes to messing with your body, but I'm very comfortable with risk.
Evolution is pretty random (or is it chaotic?). There are so many permutations that we have a DNA sequence that is very, very good for surviving in our world. It could be better though, and at this point in our civilization natural selection will not get us there.
Genetic engineering is inevitable. It will happen. In 10 or 20 or 100 years when it becomes practical there will be "conservatives" who are against it and "liberals" who are for it. They will fight for a while but in the end science will win, because science always wins in the long run.
I am not against genetic engineering, it is just that when something seems too easy I get suspicious. Obviously medicine is helping in a lot of ways, the body is not able to fix every problem by itself.
Perhaps I am missing out big time by not using drugs. Some famous works of art are probably the result of drug use (how much of it, I don't know). I also remember a recent anecdote about a rock musician meeting Tony Blair and asking him how he manages his workload. Answer: "Certainly using different drugs than you" - of course it could just be "enthusiasm" being the drug, I don't know.
If you could become a world famous artist in exchange for living 10 years less, would you do it? Or whatever is your ambition (invent the Google killer, whatever).
My ambition is to develop or help develop a serious medical breakthrough, like curing HIV. So yes, I would take 10 years, 50 years, maybe even instant death for making such a profound positive impact on humanity.
I'd also like to take over Equatorial Guinea, but the current regime may fall before I get the chance.
The body also produces some drugs that are outright bizarre. DMT occurs naturally in the brain and is one of the most potent naturally occurring psychedelics. I would be extremely interested when and why the brains of humans or our predecessors started producing DMT.
Drugs work because your body has the ability to react to them.
If your body can react to drugs is, usually, because there are internal receptors that can bind to them.
But of course naturally occurring concentrations of 'drug'-like components are much lower and extended over time than a pill, and the components themselves are milder than their drugstore counterparts (except counted instances such as norepinephrines). Besides the fact that generating them requires (usually) exercise (for example, for endorphines and melatonin/cortisol/tyroxine fine-tunning), and/or yoga-style body control.
A report from your friendly biomedical biologists.
