|E. Bates, et. al.
On the Evolution and Development of Symbols: Bibliographical Excerpts
"In our view, these recent discoveries strongly support the theory that the human Language Acquisition Device (McNeill, 1966) evolved through a recombination of preexisting capacities into a novel configuration. The argument can be summarized as follows. 1) Language can be viewed as a new machine created out of various cognitive and social components that evolved initially in the service of completely different functions. 2) This construction process probably came about through heterochrony, or changes in the growth patterns of one or more cognitive-social capacities. We can infer that at some point in history, these "old parts" reached a new quantitative level that permitted qualitatively new interactions, including the emergence of symbols. 3) The orchestration of these components into new combinations may have required the intervention of formal causes, task constraints that contribute much of the structure of the eventual linguistic-symbolic outcome. 4) If the evolution of language involved changes in the regulatory genes, and considerable interaction with task constraints, then it is likely that the process is at least partially repeated in the ontogeny of individual language users. 5) At least some forms of language deficiency may result from a deficit in one or more of the nonlinguistic components that underlie the capacity of symbols." (Bates, E. , et al. (1979) On the evolution and development of symbols. Academic Press, New York p. 31)