So, laughter.
Sex and orgasms are pleasurable because they're important for procreation (and perhaps pair-bonding). Food is pleasurable too, in a not dissimilar way. In fact most things that our bodies need to function and recreate optimally are pleasurable (ignoring things like salts and sugars which we enjoy too much, due to their scarcity of availability for aeons but over-abundance now).
Animals enjoy those things too. But most animals don't laugh. The only animals which display a sense of humour (as far as I know) are some varieties of non-human primates, dogs, elephants and possibly dolphins. These are all pretty smart animals with the capability to develop complex social structures.
The tl;dr of it all is do you think laughter [could be said to be] the social/group bonding equivalent of an orgasm? It's a natural rush we (usually) get from communicating with each other. There's no other obvious explanation for it that I'm aware of.
It's a study which is conducive to your theory; laughter releases hormones that reverse the effects of a stress response.
That being said I do think it's important to take care with how we think of biology in conjuction with psychology and social behaviour. Not everything we do has a strict evolutionary purpose.
Ah, I used to ponder this sort of thing as a teenlad too. I considered that, ostensibly, all of our behaviours have a, as >>3496 put it, strict evolutionary purpose behind them, with the seemingly sole exception of seeking entertainment. I thought that was significant in some way. We eat, sleep, mate - but go and see a stand-up comedian? What purpose does that serve? How does seeking out an opportunity to be entertained advance us as organisms?
As >>3496 says, that study is related to the very 'theory' you're proposing. In fact, all of the other examples of reinforcing behaviours you cite in your first post are either wholly or very strongly effected by the dopamine reward pathway. Pretty much everything that encourages us to do anything is; be that eating food, having sex or taking drugs.
There are evolutionary goals that can be achieved through the sharing of societal mores and interaction that happens at a comedy show. Generally, anything that reinforces "getting on with people" ties into the whole altruism gig.
>>3497 >Ah, I used to ponder this sort of thing as a teenlad too.
What a coincidence! I used to be an unnecessarily condescending dickhead when I was a teenlad.
