Humans and great apes have shared the same rhythm in laughter for 15 million years

All living great apes, such as bonobos, gorillas and orangutans, have the ability to laugh, but until now it has not been analyzed how human laughter may have changed over millions of years of evolution or its possible relationship with language.

A new study led by the University of Warwick (United Kingdom) analyzed laughter recordings from four orangutans, three bonobos, four chimpanzees and four humans between six months and seven years of age, to measure individual sequences.

All were recorded in their natural environments during playful and controlled interactions with familiar people, who elicited vocalizations, both during play and by tickling them.

The study, which publishes Communications Biology, he focused on rhythmic structure, that is, on the time intervals between successive bursts of sound, rather than on pitch or intensity.

In all these sequences the same pattern was found: All species produce laughter with evenly spaced rhythmic intervals between successive sounds.

The researchers propose that this basic rhythmic structure was already present in a common ancestor 15 million years ago and has been remarkably conserved, as all living great apes continue to show the same underlying pattern.

Laughter has become an unexpected clue to try to understand how human beings developed the ability to speak.according to researcher Chiara de Gregorio, from the University of Warwick.

Laughter is common to all living great apes and, when compared, “we can see that a basic rhythmic structure has remained unchanged since our last common ancestor. That is extraordinary,” he noted.

Although the basic rhythm remained constant, the human has become faster, more variable and has acquired sophisticated context-dependent control.

In fact, only humans have the ability to control when and how they laugh depending on the context: uncontrollable laughter when tickled differs markedly from polite laughter in a meeting, nervous laughter after making a mistake, or contagious laughter that spreads among a group of friends.

Thus, the same underlying rhythm is shaped by conscious control to communicate, through laughter, different emotions and intentions.

The paper suggests that throughout the evolution of great apes, our ancestors gradually developed greater control over the timing of their vocalizations, including laughter. That sophisticated vocal control is a fundamental pillar of speech.

Laughter, being evolutionarily older and having remained common to all living great apes, offers “a unique evolutionary opportunity” to understand the vocal transformations that occurred throughout the evolution of hominids until the first humans appeared.said the also signatory of the text, Adriano Lameria, through the University of Warwick.

The classical idea considers that early humans suddenly acquired vocal control capabilities noticeably different from those of their predecessors.

However, according to Lameria, the evolution of laughter indicates that human beings are situated “on a continuum, an extension of vocal control capabilities that had already been cumulatively perfected for 15 million years.”