[Source:  Science Daily]
The throat and facial movements that twist the air pushing through your vocal cords into words could be rooted in the well-meaning expressions primates exchange with each other, according to two recent studies based at Princeton University.
The researchers found that the oral-facial component of human speech mirrors the rhythm, development and internal dynamics of lip smacking, a friendly back-and-forth gesture performed by primates such as chimpanzees, baboons and macaques. The studies also show that the mechanics of primate lip smacking are distinct from those of chewing, similar to the separate mechanics of human speech and chewing.
These parallels suggest that in primates chewing and lip smacking — as with chewing and speech-related facial movement in humans — have separate neural controls, explained Asif Ghazanfar, an associate professor of psychology and the Princeton Neuroscience Institute, and a lead researcher for both
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