A third factor, that may have interacted with the cultural factors, may have been significant developments in language. The present argument does not require, however, the assumption that Neanderthals or other, even earlier, hominids were utterly bereft of language. Language is a collective enterprise. Language does not exist within the brain alone but equally within cultures. Yet, if they did not develop closely knit family groupings and mentoring relations across generations the long term effects of language were seriously constrained.
Human speech is thoroughly dialogical.
It is not simply a matter of sending and receiving messages, but of mutually constructing a dialogue within which plans, concepts, and meanings are created, maintained and changed. In dialogue one is constantly challenged to clarify, make explicit, and defend one's utterances. Out of dialogue grows a more self-conscious and explicit forms of declarative understanding. The neurological structures for, and the use of, speech may have existed before the Late Paleolithic but perhaps it was only in the Late Paleolithic that array of cultural conditions for the development of language , something that requires a history, or, at least, a tradition within which it may grow, interact with, and, finally, shape. The explicit creation of external signs such as those of parietal art provide clues that this development was well under way by the Late Paleolithic.