Well, and if there's one point I'm trying to make, it's that the binary laugh/don't laugh reaction obscures that there are fundamentally different essences. (Which point could perfectly well be wrong, of course. I don't think it is, but then I wouldn't.) In my opinion, to talk of "the essence of humor" is to be deluded.

Have you read Scott McCloud's book Making Comics? He puts forward a set of basic facial expressions (tied to movement of specific facial muscles) and says that all facial expressions are combinations of these. Similarly, in four-color printing you can get millions of different hues, but nonetheless the primary colors exist. The art of comedy is no less subtle, but I think the primary colors exist there too; and I speculate that they correspond to different things happening in the brain.