Something is going on with laughter. It's very weird the things that people (myself included) laugh at. More often than not it's some crazy nonsense rather than something genuinely funny. I have a sense of humor but I almost never laugh at well-crafted, intelligent jokes, even though I appreciate them.
I notice that often laughter is accompanied (even in myself) with end of thought. That at which you laugh you do not want to think about further, even if it's actually interesting. You recognize it as bizarre, something that does not conform to your mental image of the world and so you dismiss it by laughter. People who laugh at ideas they deem crackpot are very rarely the ones that understand them.
There's also, I think, a strong link between (a particular type of ) laughter and strong insecurity/femininity. People laugh in social situations when they feel insecure. There's a very distinct, insecure laugh that is easy to recognize. People who are dominant in social situations never laugh like that. It's usually beta males and nerds like myself that laugh like that. Such laughter serves to signal to others your low social status and makes it easier for others to place you in terms of status. If you pay attention, you will notice that high status people react very differently to situations that make beta males laugh. They often make a remark, a joke, do something intelligent and direct, and keep a cool head.
I started trying to laugh much less and in the process I've noticed how my thinking has gotten better and deeper. I'm really starting to think that laughter is an enemy of thought.