The laughter for which the hyena is famous may not be laughter after all, a new scientific study has recently concluded. According to the results of an acoustic analysis performed by a group of experts on “vocal” samples provided by a number of the beasts, the animals most often make the noises when they are struggling to get food, fighting among themselves, or in other forms of social dispute in general. This seems to hint at the idea that the sounds they make may actually be a form of expressing frustration, much in the same way some people curse when they are angry.

University of California in Berkeley (UCB) visiting biologist Professor Nicolas Mathevon, originally from the Jean Monnet University in France, said that, “When a group of hyenas is feeding upon the prey you hear a lot of these giggles, especially during conflict between two individuals.” The expert has led a UCB team in analyzing the communication patterns of 17 captive hyenas. In their study, the scientists looked at the pitch, volume and length of the “laughter,” and then related the results to the social status of each animal that created it.

They learned that hyenas with a lower social status were always making sounds that were more varied in all three parameters, and that they also generated them in a much higher pitch than higher-ranking hyenas. That is to say, females of a high social status were more likely to hang on to a certain type of growl, which, most likely, was recognized and feared in the group. These beasts are matriarchal animals, meaning that females of the species rule the roost and that the males are subordinates.

“The females are dominant, and there's very strong hierarchy, especially when they are feeding. Apparently, the subordinate animals emit more giggles than the dominant ones. That’s why we think it's more a frustration call,” Mathevon told LiveScience in an interview. “The hyena society is so complicated that they really need efficient means of communication between individuals. I think this call is just part of a very complex communication system, which includes a lot of different sounds, as well as chemical systems and visual systems,” he added.