Researchers have discovered that rats can laugh - we just can't hear it because it's ultrasonic! Play vocalisations are therefore a great way to disambiguate whether two animals are actually ...

When rats play with each other or are tickled ... The noise we make when we laugh is very similar to the play grunts that apes make. Unlike speech, producing this sound involves almost no movement ...

We have known since the 1990s that rats laugh. We also know that if tickled by people, rats will giggle more readily and form bonds with whoever is playing with them. Rats are capable of empathy ...

Happy chimpanzees make very distinctive hooting sounds, and both great apes laugh with open mouths, just like we humans do. Rats also play, especially tickle games. While humans have tickly feet ...