O.P.

Similarly, is anyone aware if any work has been done on why we have a sense of humour?

Not really what your looking for, but this question immediately made me think of the novel The Road to Mars by Eric Idle. It's a silly little comedy/sci-fi romp which mostly follows the adventures of a comedy duo who are traveling the show biz circuit through our future solar system.

This duo have a robotic secretary named Carlton who is obsessed with understanding the human concept of humor, and is traveling with his bosses as a means of researching his doctoral thesis on the subject. In the end his research posits the existence of a primary force in nature called "levity" which is the polar opposite of gravity, and exerts a generally expansive, uplifting effect on all matter in the universe.