Anthropologists at the University of California, Los Angeles have found that laughter - a phenomenon we are used to thinking of as a human characteristic - is inherent in many other animals, according to the Daily Mail.
Scientists analyzed data on sounds that resemble laughter in different animals. When people laugh, they kind of let others know that they are having fun and invite them to join. Many animals that play have corresponding vocalizations for the same purpose. These sounds help the animals to signal that they are in a playful, not aggressive mood. In the animal kingdom, where even games for human taste are rather rude and rather resemble fights, such signals are very important for communication.
Anthropologists have examined vocalized recordings for loudness, duration, pitch, rhythm, and other characteristics. In addition, they compared them with other features of play behavior in animals, such as the "playful" looks of dogs and primates. According to the American hypothesis, all this is an analogue of human laughter, which also signals the desire to play. Our laughter is the same version of the play signal that was present in many animals earlier in evolution. Therefore, the study of "laughter" in animals can also shed light on the function of laughter in humans. However, there is a problem: for many animals it is difficult to make such recordings, since their "laughter" is very quiet.
It is curious that hyenas, whose ability to laugh is known, do not make these sounds at all when they are having fun. Their "laughter" sounds in situations where hyenas feel threatened, attacked, or, so to speak, complain. Older hyenas "laugh" in a lower voice, while young individuals make high-pitched sounds. Among those animals that laugh when they feel good, the researchers name magpies, parrots, cows, dogs, foxes, mongooses, seals and various primates.
The research results are published in the journal Bioacoustics.