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Hyena's giggles provide insight into language development


Hi, my name is Frederic Theunissen. I am a researcher at Berkeley and we're here because I am studying the vocalization of the spotted hyena. We have a colony of 21 captive hyenas here. It's the largest colony in the world and this is really a rare opportunity that we have here to record the sounds of one of the most vocal terrestrial mammals.   

The spotted hyena produces about 15 different types of vocalization and we're interested in describing all these vocalizations, and seeing in which context it produces these vocalizations; and seeing whether they have some of the open-endedness and plasticity that you might find in a more sophisticated language, like humans' language, in the sense that it would produce a different sound in a different behavioral context.  And it requires higher perceptual abilities in the sense that if you are going to use signals to tell whether this is a dominant or subordinate animal, you need to be able to perceive this differences. Learn to recognize them. So, it goes as kind of evolution of complex signaling system goes hand in hand in evolution of cognitive ability. Both perceptual and cognitive in the sense that you need to interpret them in a social context.

We've been recording the hyena giggle and the giggle is produced in a context were the animal is frustrated. So, if you think of it as a laugh, it's more of a nervous laugh than just a happy laugh. They are usually in a situation where they want to get something and they don't have access to it. And so the giggle happens a lot in free-living animals at kills where one animal might be dominating the kill and not letting other animals have access to the food. 

Our first question was do different animals have different giggle sounds - do they produce different giggles?  And we found that, yes, indeed each animal has its own very characteristic giggle sound. So, you could tell who's giggling just by listening to the giggle sound. But what we didn't expect and we also found is that there was a signature of the dominance of the animal. 

Being able to study an animal which is not a primate but which also has a complex social structure and actually a communication system that is as sophisticated if not more sophisticated then what we see on human primates, allows us to really understand what was needed to evolve the ability of language.

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