New research from the University of Warwick suggests that the rhythm of human laughter has been surprisingly consistent for at least 15 million years. By comparing the laughter of humans and other great apes, researchers found evidence that this ancient vocal pattern may provide valuable clues about how human speech gradually evolved.
Humans aren’t the only primates that laugh. Chimpanzees, bonobos, gorillas, and orangutans all produce laughter, but scientists have long wondered how these vocalizations have changed over millions of years and whether they can reveal anything about the origins of human language.
Researchers analyzed recordings of laughter from four orangutans, two gorillas, three bonobos, four chimpanzees, and four humans. Their research is communication biologyexamined 140 individual laugh sequences.
Despite the differences between the species, the research team found surprising similarities. All species produced laughter at evenly spaced rhythmic intervals between successive sounds.
Researchers believe this common rhythmic pattern originates from a common ancestor who lived about 15 million years ago. They propose that the basic structure has remained remarkably stable throughout the evolution of all modern great apes.
Dr Chiara de Gregorio, Honorary Research Fellow in the Department of Psychology at the University of Warwick, said: “How did humans evolve such amazing linguistic abilities?Speech leaves no fossil record and complex language exists only in our own species.But we have 15 “We found a million-year-old clue in an unexpected place: human laughter. Unlike speech, laughter is shared by all living great apes. By comparing the ways in which different species laugh, we can learn something fundamental.” It is surprising that the rhythmic structure has not changed since our last common ancestor. ”
Human laughter has become more flexible
Although the underlying rhythms appear unchanged, human laughter has become faster, more varied, and far more adaptable than that of other great apes.
People can consciously adjust when and how to laugh depending on the situation. The natural laughter caused by tickling is different from the polite laughter during a meeting, the nervous laughter after making a mistake, or the contagious laughter shared between friends. Although each serves a different social purpose, they all hold the same basic rhythmic foundation.
The growth of this ability to control the timing of vocalizations likely developed gradually over the course of great ape evolution, the researchers said. Increased levels of vocal control, including excessive laughter, may have provided one of the key building blocks that ultimately made human speech possible.
A window into the evolution of speech
Because spoken language has no direct fossil evidence, scientists have few ways to trace its earliest origins. However, laughter is evolutionarily much older than speech and is common to all living great apes, providing a unique opportunity to study how vocal communication evolved.
Dr Adriano Lamelia, Associate Professor ApeTank in the School of Psychology at the University of Warwick, said: ‘It is impossible to directly assess the precursors of language from extinct ancestors. Laughter is evolutionarily ancient and common among all extant great apes. “This provides a valuable evolutionary window into the changes in voice that evolved over the course of human evolution before the first humans appeared on the scene. This contrasts with the classical notion that the first humans suddenly acquired vocal control.” The evolution of laughter shows that humans are an extension of our ability to control vocalizations, which has been honed cumulatively over 15 million years. ”
