As The Humor Code notes several times, humor can't stand to be examined. It falls apart and fails, like magic does when you explain a trick. That said, the authors fly off around the world, looking at comedy and humor and what makes them tick in different societies. From their Denver base, they get to visit with New York admen, Palestinian sketch satirists, Japanese standup students, and eventually take all they have learned and demonstrate it at the Just for Laughs festival.
Suffice it to say comedy gets to keep its secrets. There is no universal formula. Different jokes appeal to different folks. Different societies take offense at different things. American standup filth doesn't play as well in say, Yemen.
Many societies have moron jokes, poking insults at some minority or other country: Irish jokes in England, Okie jokes in the USA, Newfie jokes in Canada, Polish jokes in North America (in the sixties). That's about as universal as The Humor Code gets.
There is so much they miss, it is criminal. They visited Tanzania to learn about laughing disease, but never mention the infectiousness of laughter. That the top selling record in the USA was once just laughter. People listened and couldn't help laughing. They miss the printed word entirely: the setups of Robert Benchley, the knife twisting of Celia Rivenbark, the Dementia Praecox of SJ Perelman. And most strangely, they don't examine delivery and timing - how one person can make reading the telephone book funny and two people telling the same joke get entirely different reactions. How Peter Cook could keep people howling all night without ever telling a joke, and no one could remember a thing from the experience except their sides hurt all the next day and they had the time of their lives. (They do mention Henny Youngman's signature line in passing.) But then, none of that would fit in their theory anyway.
What I found most interesting was their time with the cartoon editor of the New Yorker. They put together a list of the approaches that make for a winning caption: finalists' entries didn't waste words on obvious visual elements, did not use excessive punctuation like question marks and exclamation points, and at 8.7 words, were a word shorter than the rest. Also, they did double duty. Being the funniest isn't enough; they have to make a point. Oh.
We are left with a travelogue, filled with bad drivers, missed connections, too much alcohol and not much new data. The stories are backfilled with references to academics and studies that follow references out onto tangents.
If you know going in they weren't going to discover the holy grail, it makes the Humor Code much more readable and enjoyable. It's just a romp in comedy around the world.