Lip-Smacking Primate Hints at Speech Evolution

Speech is integral to who we are as a species, but how did it evolve? The lip-smacking sounds made by a rare African primate may provide a clue, a new study says.

Most primates make rudimentary calls that consist of one or two syllables. But the gelada—native only to the grasslands of the Ethiopian plateau—displays “rapid fluctuations in pitch and volume” akin to human speech. (Listen to a clip of the gelada’s chatter.)

A male gelada flashes his eyebrows menacingly at a bachelor male. Photograph by Michael Nichols, National Geographic


The similarity has researchers’ tongues wagging.

“Our finding provides support for the lip-smacking origins of [human] speech, because it shows that this evolutionary pathway is at least plausible,” study leader Thore Bergman, of the University of Michigan in Ann Arbor, said in a statement.

Lip-smacking is unlike other primate calls in that the rhythm corresponds to the opening and closing of parts of the mouth—which in turn, well, smacks of human speech, according to the study authors. (Also see Chimp ‘Dinner Conversation’ Proof of Ape Speech?”)

Monkey Business

When he began doing fieldwork in 2006, Bergman hadn’t made the connection—but said he was often tricked by the prattling primates.

“I would find myself frequently looking over my shoulder to see who was talking to me, but it was just the geladas,” he recalled in a statement. “It was unnerving to have primate vocalizations sound so much like human voices.” (Watch a video of a gelada “talking.”)

gelada with baby picture
A male gelada watches a female with infant. Photograph by Michael Nichols, National Geographic


The uncanny chatter was so unique that it made Bergman wonder: could lip-smacking be a precursor to human speech? When he read a paper suggesting just that, it prompted him to analyze recordings of the geladas’ unusual vocalizations—also known as “wobbles.” Those recordings revealed structural similarities with human words. (Related: “‘Talking’ Whale Could Imitate Human Voice.”)

Bonding Time

Geladas unique vocalizations may have evolved as a social glue: The species has a tight-knit social structure consisting of family groups within larger bands.

If the lip-smacking of the gabby gelada is indeed a forerunner of the shouts and murmurs of people, Bergman theorizes that it may serve similar functions as human speech, not just as a method of communication but to bond individuals.

Which leads us to think that the invention of gossip can’t have been far behind.


Stefan Sirucek is a writer and journalist who reports from both sides of the Atlantic. He's written for the Huffington Post and Wall Street Journal. Follow him on Twitter at @sirstefan.