If you thought laughter was just a human trait, you couldn’t be more wrong. Many animals have their own unique ways of expressing joy.

Now that we know octopi like to play with cameras, it’s time to investigate other forms of animal play. Did you know that rats laugh when you tickle them? This ...

When the cat’s away, to paraphrase an old cliché, the rats will play. Neuroscientist Jaak Panksepp, working at Washington State University, has devoted a decade to watching that play. And from those ...

They could almost be a couple of kids—chasing, tumbling and squealing with apparent glee. Well, almost like kids. For one thing, their squeals would be impossible to hear without the electronic device ...