Just over forty years ago, Andrew (1963) suggested that language arose

gradually “from an already well-developed and elaborate system of vocal

displays modulated by the lips and tongue.” (p. 94). To Andrew, the lip-

smacking and grunting of baboons were prime examples of such displays. Later,

MacNeilage appealed to lipsmacking as a possible origin of the syllabic frame,

pointing to its biomechanical action and early vegetative origin (MacNeilage,

1986, 1998). I agree with MacNeilage that lipsmacking is relevant to linguistic

evolution, so relevant that it seems strange when theorists say nothing about it.