How chimpanzee ‘lip smacking’ can unlock mystery behind human speech

Researchers are a step closer to solving one of the greatest puzzles of evolution, after discovering that chimpanzees smack their lips in a rhythm like that of spoken language.

That monkeys use vertical jaw movements to communicate with each other was already known, but now a new study focusing on chimpanzees has revealed that the great apes’ mouth signals follow “the same pace as humans speaking”, Sky News reports.

The scientists believe their findings, outlined in a newly published paper in the journal Biology Letters, prove that human language has “ancient roots within primate communication”.

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According to ScienceAlert, “no matter what language we are speaking, humans around the world are known to open their mouths two to seven times per second while talking (2 Hz to 7 Hz)”.

Although this rhythm has been seen in other monkey species such as gibbons, orangutans and macaques, “the lip smacks of the closest species to humans - the African great ape - had never been studied” until now, adds Sky News.

The researchers studied video recordings of four chimpanzee populations - two in European zoos and two in the wild in different parts of Uganda - and discovered that they produced lip-smacks at an average speech-like rhythm of 4.15 Hz.

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Study author Dr Adriano Lameira, from Warwick University department of psychology, said the results “prove that spoken language was pulled together within our ancestral lineage using ‘ingredients’ that were already available and in use by other primates and hominids”.

“This dispels much of the scientific enigma that language evolution has represented so far,” Lameria said, adding that “our ignorance has been partly a consequence of our huge underestimation of the vocal and cognitive capacities of our great ape cousins”.

The scientists are calling for future research across primate species in order “to find out how these human-like rhythms arise in both individuals and populations”, says ScienceAlert, which adds that “knowing this might just tell us more about the evolution of our own language”.