Related tangentially to my earlier mention of hominid speech, I would like to bring up an interesting theory proposed by Spengler: he once asserted (in
Man and Technics
, I believe) that for the early generations of homo sapiens, speech was a privilege, a difficult task to master, and an art only accessible to the more important (and presumably male) adults. By the arrival of organized agriculture and especially with the first high cultures (Sumer and Egypt), speech had completely filtered down to the masses and even to children, while reading and writing now became the distinguishing marker of the elites. (It should be noted though that both back then and today, the sophistication and refinement of the elites' vocabulary, syntax, and semantic skills remain far superior to the common man's speech-- something of which both parties are acutely aware of)
Spengler doesn't cite evidence for his theory, of course; he relies instead on his favored method of historical analogy. But there is something compelling to the idea, I think, and it would seem to fly in the face of the accepted theory re: speech development-- for which there is equally little evidence, I might add. Anthropologists all seem to imagine the earliest talking humans as ultra-communitarian groupings with men, women, and children communicating on a relatively equal basis, delegating simple division of labor in a democratic fashion, etc. Estate groupings (or "class divisions", in Marxist jargon) and true social stratification, we are told, first appear with the rise of agriculture/civilization and the concomitant need for central planning, stricter division of labor, etc.
But it seems just as likely that the vast majority of pre-agricultural humans in these primitive bands and tribes were capable of only grunting perhaps a few basic words for everyday objects, while the enunciation of complex clauses and ideas was the possession of a small coterie of leaders responsible for ritual, organization, and strategy.