Why do people laugh when they see jokes?

Now, laughter is the brain's answer to "happiness"

The so-called fun is a minor violation.

You saw a coquettish young man walking in the street and suddenly slipped on a banana peel. You might laugh.

If you see an 80-year-old man fall on a banana peel, you won't laugh.

Because you can expect the result, the former is a minor violation, and the latter may bring serious consequences.

Laughter is not only influenced by genes, personality and rationality, but also by "threshold". It's the same reason that it's not easy to laugh after reading a lot of bad jokes.

People don't laugh all the time, because the human body has a feedback mechanism and won't always be in a comfortable state of producing dopamine, so our ancestors won't go hunting or reproduce.

On the other hand, if some primitive people can laugh all the time. Then he can't survive and reproduce, that is to say, he was eliminated by "natural selection"