pleasure vs pain

What is pleasure?
What is pain?
What is the difference between pleasure and pain?

I believe that pleasure and pain are very similar, they are both sensations, they are both interpretations of stimuli. The big difference between them is that one creates a reward response in the brain (pleasure), the other creates a punishment response in the brain (pain).

If they are both responses of the brain to stimuli, why do we perceive them as we do? I mean, why don't we like pain and dislike pleasure?

If we would like pain, our chances of killing ourselves would be bigger. For example, if we put a hand in fire and we like it, there is a bigger chance of keeping it there and provoking severe burns.

People who don't feel pain usually die young because they accumulate injuries and they don't feel diseases, so pain has a very important role in survival.

Thus, we are programed by evolution to interpret some stimuli as pain and others as pleasure. Objectively, there is no difference between pleasure and pain but subjectively there is a huge difference.

One man asked why do we feel pain as we do, why don't we see red lights and hear alarm sirens when we put a hand in the fire? A biologist answered that red lights and alarms are not as effective as pain at making us get away from danger, thus, saving our lives.

It's obvious that only beings that can move can be selected for pain. I'm pretty sure that plants don't feel pain, at least not the way we do. They may feel some sort or pleasure in the light and pain in the shadow, but I don't think a tree will feel pain as we chop it down, simply because trees which felt such pain did not have bigger chances of survival and reproduction.

Nature selects for survival, it doesn't care what you feel, it can't care. We feel pain and pleasure as we do because it's good for survival.

There will always be suffering in this world, not only human suffering, but other animals will suffer. As long as life exists, suffering will also exist. We may strive to reduce suffering as much as possible and this, I think, is a worthy gole. Suffering will end along with life itself, unless if you believe in eternal suffering in some hellish place (in the eventuality of afterlife).