I agree that humor is from dissonance (wikipedia says "incongruity" but it's basically the same thing), but I'm also trying to figure out the social aspects that even allow that dissonance and difference of fact vs. reality to occur. There must be a level of communication needed for two individuals to have the same reaction to an event, word, sentence, stimuli etc.
I know other species communicate, and many communicate very well, but humans seem to take it a step further. Enjoyment seems to differently expressed than humor. Many animals show enjoyment or contentment (cats purring, dogs wagging their tails), but I've never known about other species grasping anything similar to humor and "laughing."