For what it’s worth. I have not read the book mentioned below — it could be full of philosophic and scientific errors as far as I know; but then again, maybe not — but it sounds interesting. On the University of Texas blog ShelfLife@Texas, Jessica Sinn writes:
Using a Darwinian approach, MacNeilage, professor of psychology, deconstructs the miracle of human language in “The Origin of Speech: Studies in the Evolution of Language” (Oxford University Press, 2008). Piecing together a mixture of linguistic and nonlinguistic sources such as evolution theory, psychology, animal behavior and neurobiology, MacNeilage assembles a thought-provoking overview of how our powerful communication system originated and evolved. Challenging Noam Chomsky’s theory that speech is naturally hardwired in brain patterns, MacNeilage explains how it changed in response to evolutionary pressures for more efficient communication. His proposals include the observation that speech formed from bodily movements, such as chewing, smacking and swallowing, which paired with vocalized syllables, transcended into language.