Humans are not the only animals that communicate. Birds sing to attract mates, dolphins use signature whistles that identify individuals, and many primates produce complex vocalisations that help them coordinate their social lives.

By studying these communication systems, researchers can reconstruct some of the evolutionary steps that eventually led to one of our defining traits: language.

Language doesn’t just mean making sounds – it requires an extraordinary ability to control them. Human speech demands precise coordination between breathing, the vocal folds across the larynx, and our tongue, lips and jaw.

Humans’ closest living relatives – chimpanzees and bonobos – possess vocal tracts that are more similar to ours than scientists once believed. Yet they do not seem to have the same fine voluntary control over the structures – starting with our lips and tongue – that allow us to produce rapid sequences of speech and such diverse sounds.

This raises an intriguing question: when did our ancient ancestors begin to acquire this remarkable vocal control? One possible clue comes from an unexpected source: laughter.

The evolution of laughter

For several years, I have studied the rhythmic structure of vocalisations in non-human primates. Rather than focusing on what calls mean, I have been interested in how they are produced.

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