Laughter's steady rhythm traces the evolution from apes to human speech

TL;DR
A cross-species study of laughter in orangutans, gorillas, bonobos, chimpanzees, and humans finds laughter isochronous across extant great apes, with tempo accelerating and variability increasing over roughly 15 million years of hominid evolution. Tickling-induced laughter is more regular than play, and humans show the most context-sensitive tempo changes, indicating progressive gains in vocal control that likely paved the way for speech and language.
- Rhythm and timing in laughter reveal that human vocal plasticity falls on a hominid continuum | Communications Biology Nature
- To Reveal the Rhythmic Roots of Laughter, Just Tickle an Ape The New York Times
- Get a load of this: Humans and great apes share similar giggles AP News
- Scientists studied the laughter of apes – and discovered something incredibly human-like BBC Wildlife Magazine
- What an ape’s laugh can teach us about human language Yahoo
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