There are many many societies around the world that have survived for millennia with cultural practices that you and I might think are abominable.

No argument here.

The fact that they have survived is an indication that there are many paths to 'happiness'.

Societies do not survive because their particular cultures make their members happy, they survive because their members manage to reproduce generation after generation and resist external influence to the extent that their culture remains intact. The word "they" in this context needs examination as well. Who, exactly and specifically, does a particular society/culture work for? Or make happy, as you put it?

I've no idea about the answers, but they are certainly relative.

I don't think anyone here is arguing for either extreme, maybe with the exception of kcurie. I'm not interested in rounding up all human males that are marrying 10 year old females, for example, but I'm not going to take the relativist view that this is a valid path to happiness for all people involved.

I'll put my money where my mouth is: I'll pin my baseline assumptions on the universal declaration of human rights. Or at least desire the debate to begin there. "Western" assumptions or not, an honest reading of the document contains enough material to make the blood boil of anyone in favor of coercive, hierarchical systems - the sort of systems we are prone to and have engaged in since the agricultural revolution. In that context we've gone from the king as god to the systems we have today in which there is a broader distribution of power. Why not take this further?

We need more people studying the concept of happiness. The fact that happiness is relative, at least in a quantitative sense, doesn't stop the Dalai Lama from coming up with some good philosophy on the subject. Surely the liberal, secular world can come up with something better than the null solution "lack of complete understanding means we can say nothing"?

you are the media you consume.