No one seems to address the very germane question of whether consciousness is separable from language, or rather communication more broadly. Is it possible to have language, and not be conscious? Is it possible to be conscious and not have language?

Though no one takes Julian Jaynes seriously these days, but I think his ideas of the development of language preceding consciousness are as good as any other theories I've read.

http://www.amazon.com/Origin-Consciousness-Breakdown-Bicamer...