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Research with great primates reveals how the rhythm of laughter remained similar to humans for millions of years and can help understand the evolution of vocal communication
Scientists analyzed different primate species to investigate how the control of sounds, variation of laughter, and vocal flexibility evolved to reach the characteristics present in humans.
Primate laughter maintains characteristics similar to humans
According to a study published on June 25 in the journal Communications Biology, the rhythm of great primate laughter has remained similar to humans for at least 15 million years.
Furthermore, the research indicates that laughter has undergone changes throughout evolution. Thus, it became faster and more variable among hominids.
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According to the researchers, this transformation may be related to the development of human speech. However, further analyses are still needed to fully confirm this hypothesis.
Research analyzed different species of great primates
To conduct the study, scientists evaluated five groups of existing great primates.
Sequences of laughter were observed from:
- Orangutans (Pongo pygmaeus);
- Gorillas (Gorilla gorilla);
- Bonobos (Pan paniscus);
- Chimpanzees (Pan troglodytes);
- Humans (Homo sapiens).
In total, 140 sequences of laughter were examined. Additionally, researchers measured the intervals between each sound emission.
As a result, it was identified that the laughter of great primates presents an isochronous pattern, meaning it maintains regular intervals between sounds.
Rhythm of laughter may reveal paths of speech evolution
Even so, scientists point out that the main groups of hominids developed different vocalization repertoires.
However, laughter remained conserved among the species. Additionally, this characteristic appeared independently of age or gender.
According to the authors Chiara De Gregorio, Marina Davila Ross, and Adriano R. Lameira, researchers affiliated with the University of Warwick, in the United Kingdom, the differences in the rhythm of laughter may indicate changes in vocal control.
Thus, the study suggests that the flexibility of sounds gradually increased during the evolution of great apes and humans.
Humans can adapt the rhythm of laughter
Furthermore, the research revealed an important difference between humans and other primates.
Humans can change the speed of laughter depending on the context. For example, a person may laugh faster during tickling than during a joke.
On the other hand, other primates analyzed do not have this same ability to adapt.
Consequently, the researchers indicate that the temporal variation of laughter can convey social, emotional, and behavioral information.
Results expand studies on the origin of human communication
Therefore, the research expands previous findings on primate vocalizations.
Previously, studies had already identified similar patterns in orangutans. Now, the new data includes other great primates.
In this way, the results reinforce the possibility that the development of human vocal control was an important step for the emergence of human language.
However, according to the researchers, more studies with new samples will still be necessary to confirm this evolutionary relationship.
