Chimps Smack Their Lips in Rhythms Uncannily Similar to Human Language - ScienceAlert

The way chimpanzees smack their lips together has a similar rhythm to human speech, and a new study suggests this could be a clue to where our ancestors got their knack for language.

Comparing recordings from four chimp populations, both wild and captive, researchers have now found chimpanzees also produce lip-smacks at an average speech-like rhythm of 4 hertz.

In great apes, however, the fastest mouth rhythms tend to keep a steady rhythm around a single hertz, so the authors think the variability of lip-smacking frequencies in chimp populations may imply social factors instead of hard-wired signals.

Still, between captive and wild populations, the authors found no systematic difference in mouth signals, probably because of a "substantial overlap in the range of rhythms present" among individuals in different groups.