Why do hyenas laugh?

A Hyena's giggle is not actually laughter, but a sound of frustration. New research found a way to distinguish individual hyenas based on the peculiarities of their, well, let's call them fighting words.

Until now these squeaky cackles have not been well understood by scientists. Researchers recorded the sounds and did the first ever acoustic analysis of them to understand how the calls vary between individuals, and when they are used.

The scientists found that hyenas usually made these noises when they were fighting for food, or in some kind of social conflict.