Animal laughter

BBC reports that Professor Jaak Panksepp have discovered that animals other than humans exhibit play sounds that resemble human laughs. His findings are published in the journal, Science, and can be found here.

The article even cites Panksepp speculating about higher cognitive function like humour:

"Although no one has investigated the possibility of rat humour, if it exists, it is likely to be heavily laced with slapstick."

I can't tell if he was dead serious or joking with the reporter.

link