@Seriost,
Yeah. That is an interesting idea. It's not entirely impossible. I didn't think of that.
I just think that the brain is a physical organ can't can't really have changed.
But maybe it does not have to. The causes of happiness could be determined by culture and the influence of out environment, like other behavior is.
I mean, someone is not dark-haired because his parents taught him that, but he is friendly or not because they did.
Our physiological bodies, that could not have changed so fast, could be more of a framework for changeable attributes, that are adapting to our environment. And reasons for happiness are not just set in stone, they would evolve. It would be a great way to be adaptable.
Am I being unclear? Was that what you meant?