[neuronic]

Since this is so broadly spread among species I wonder if there are other forms of laughing that aren’t easily detected if you don’t know about it. Does some form of muscle spasms occur in all of these animals?

Closely watching my cat now.

[rcarmo]

You should watch it closely anytime, it is very likely to be plotting something even if you can't tell it's laughing manically...

[KineticLensman]

> Since this is so broadly spread among species I wonder if there are other forms of laughing that aren’t easily detected if you don’t know about it

Yes. As per the original research article, some of the vocalisations are outside the range of human hearing.