Spotted hyenas grunt and growl. But you know what they're famous for. [Hyena sounds.] So what's all the laughing about? Well, field researchers have noticed that groups of hyenas tend to giggle around ...

Like many other animals, hyenas can howl and grunt and growl. But what makes them giggle? Scientists studied a variety of hyena laughs to come up with the beginnings of an answer. Limited time: Save ...