>My question is a serious one, please do not make fun of it this way,
OK, let's try some serious examples:
If you know you won't feel bad if your child dies, then you won't go as far
to protect your child as you otherwise would. Then you might end up with no
one to pass on your genes.
If sticking your hand into a fire isn't painful, then you'll incinerate
yourself or die of infected burns.
If you don't get angry when others beat you up and take your lunch, you'll
(a) keep letting them beat you up until they kill you, or (b) starve to
If you're not afraid of the bear, you won't hide from it and the bear will
maul you to death.
In other words, you need to be able to feel sadness, pain, anger and fear in
order to have a good chance at survival. You could live without them, but
not for long.
The goal of evolution is not to make people happy. It's to enable them to
survive and reproduce. Therefore, while "negative" emotions are certainly
unpleasant, we have to recognize that they exist for our benefit.