Why do people laugh

Alastair Clarke advances this theory as "an evolutionary and cognitive explanation of how and why any individual finds anything funny. Effectively, it explains that humour occurs when the brain recognises a pattern that surprises it, and that recognition of this sort is rewarded with the experience of the humorous response, an element of which is broadcast as laughter." The theory further identifies the importance of pattern recognition in human evolution: "An ability to recognise patterns instantly and unconsciously has proved a fundamental weapon in the cognitive arsenal of human beings. The humorous reward has encouraged the development of such faculties, leading to the unique perceptual and intellectual abilities of our species.”

Humor is a topic in catastrophe theory.

My own theory is laughter is nature's way of preventing the brain from crashing like a computer running a badly written program. It has elements of expressions of both joy and sorrow as if we can't quite decide whether to be happy or sad. If worst comes to worst, we just laugh until the system is prompted to reset itself by the sheer physical strain.

Sounds like a promising new feature for Windows 9. Instead displaying of the blue screen of death, your computer starts laughing hysterically.

Humor is a topic in catastrophe theory. Here's a joke you may already know. Three people walk into a bar. The first one sets a pattern. The second one reinforces that pattern. The third one breaks the pattern. Get's 'em every time.

Three guys walk into a bar. Bartender says, "What'll you have?" First guy says "Beer". Second guy says "Beer". Third guy says "Scotch n' soda".