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[video:155946|caption:The rhythmic vocal sounds made by lip smacking in wild Gelada monkeys have similarities to human speech, a new University of Michigan study shows.]

[audioplayer:146951|align:left|caption:Gelada call]

Humans are motormouths, almost effortlessly shifting about their tongues, lips, and jaws to create the complicated noises that, paired with vocalization, make up speech. Such a combination wasn’t known to occur in other primates—until recently. Baboon-like geladas in the Ethiopian highlands not only pair their vocals with particular mouth movements, but their call—an odd wailing yodel known as a “wobble”—shares qualities with human speech. “If you listen to the wobble, it undulates at a similar rhythm to the way that speech does,” with about five audible peaks per second, says Thore Bergman, a psychologist and evolutionary biologist. His finding could shed light on the evolutionary sources of human speech. But for now, Bergman is trying to figure out exactly why geladas make their peculiar call. Males seem to use it with females with whom they foster lasting bonds, indicating that for geladas, like humans, communication may be key to long-term relationships.

This story originally ran in the July-August 2013 issue as “Call Center.”

Gelada Call [nid:147266]