[Lewis Thomson (OP)]

Donald has been interested in finding the answer to this question.

"What evolutionary use is laughter? Mice, chimps and some other mammals have a laughter equivalent from being tickled. Dolphins and whales do not."

What do you think? Discuss in the comments below...

[evan_au]

It is a useful signal when rough-housing to say "I am not trying to hurt you".
...but its little consolation if a gang is trying to harm you!

[Petrochemicals]

Dolphins and whales do not."[/i]

I believe dolphins do laugh, Whales may laugh, we do not know enough. Laughter is a sign of higher intelligence, what constitutes laughter is not defined.