Humans and great apes exhibit surprisingly similar giggling patterns, suggesting a common evolutionary origin for this vocalization of playfulness, according to a new study. Researchers re-examined recordings of captive apes — including gorillas, orangutans, chimpanzees, and bonobos — being tickled, and compared these sounds with newly captured audio of four young children giggling during tickle play at home.
The analysis revealed that the chuckles of both humans and great apes follow similar rhythms, characterized by regular timing between laughs. This shared characteristic is believed to reflect a connection to a common ancestor from which these species diverhed.
"In a way, we are very similar to other great apes because we’ve been laughing in a similar way for 15 million years," said Chiara De Gregorio, a primatologist at the University of Warwick in England and an author of the study. Laughter serves as a non-verbal communication of positive emotion and playfulness across species.
While many animals can produce sounds associated with play, their vocalizations do not always align closely with human laughter patterns. For instance, rats respond to tickling with ultrasonic squeaks.
Previous research into the evolution of laughter has largely focused on facial expressions. The current study, published in the journal Communications Biology, shifts focus to the acoustic qualities of laughter. While human laughter has become more rapid and complex compared to that of apes, with variations in intensity depending on social context, the fundamental rhythmic structure appears to be conserved.
Brittany Florkiewicz, a researcher of animal communication at Lyon College who was not involved in the study, commented that the findings are consistent with current understanding and highlight the need for further investigation. She suggested that recordings of other animals known for playful expressions, such as dogs, horses, and cats, could offer more insights into the evolution of laughter.
Understanding the origins of laughter is seen as a pathway to comprehending broader aspects of human communication, including the development of spoken language. As sounds do not fossilize, scientists rely on available evidence, such as vocalizations, to trace evolutionary pathways.