The research suggests that the basic beat pattern of laughter has been conserved over the course of evolution, dating back roughly 15 million years.
A Universal Rhythm
A study published on September 5, 2025, in the journal Communications Biology has analyzed the acoustic structure of laughter in humans and great apes. Researchers compared laughter produced during tickling in orangutans, gorillas, bonobos, chimpanzees, and human children, identifying consistent rhythmic patterns across all species.
Methodology and Scope
Researchers analyzed a total of 140 individual laughter sequences. The recordings included:
- Great apes (orangutans, gorillas, bonobos, chimpanzees) responding to tickling.
- Human children aged six months to seven years being tickled in home environments.
The study was conducted by Chiara De Gregorio (University of Warwick) and Simon Townsend (University of Zurich), among others. The research was supported by the Howard Hughes Medical Institute and the Robert Wood Johnson Foundation; the Associated Press is solely responsible for content from one of the reporting sources.
Key Findings
- Rhythmic Consistency: Laughter in all five species (humans and the four great ape species) displayed similar rhythmic patterns. The sounds were produced with evenly spaced intervals, resembling a consistent beat.
- Variation in Social Play: Laughter occurring during active social play showed greater variability in rhythm compared to tickled laughter. Researchers attributed this to physical movements affecting breathing patterns.
- Evolutionary Origins: The authors state that the regular rhythmic structure of laughter reflects vocal motor control inherited from a common ancestor that lived approximately 15 million years ago.
- Human-Specific Developments: While the fundamental beat pattern is shared, human laughter has evolved to be faster and more complex. Humans are also the only species documented to demonstrate contextual control over laughter, such as the ability to suppress or fake it, which researchers consider a potential building block for speech.
"The results align with existing evidence suggesting that great apes possess more vocal control than previously recognized." — Simon Townsend, University of Zurich
Broader Context and Commentary
The study contributes to the understanding of laughter as a non-verbal communication tool that signals playfulness. Scientists have previously studied laughter in various animals, noting that rats produce ultrasonic squeaks when tickled. This study focuses specifically on audio recordings to trace the evolutionary history of the sound.
Brittany Florkiewicz (Lyon College) commented that the findings indicate a need for further investigation. Simon Townsend noted that the results align with existing evidence suggesting that great apes possess more vocal control than previously recognized.