I've been critical of Chomsky's theory of language here based on having viewed several of his talks and interviews on Youtube from over the course of the last 40 or 50 years. Seeing little change in his explanations, examples and claims over that period, I've concluded that he hasn't made all that much progress since his earliest theories about the innateness of language. But perhaps I haven't been totally fair to him because in at least some of the later talks he offers a more concrete thesis about what he means when he refers to the sudden occurrence of language in humans (which he places as occurring somewhere in the past 70,000 years or so). He argues that since language requires a computational capacity and there is no evidence for language-capable thinking in human artifacts prior to that time (but indirect evidence of it, in the presence of symbols, art and decorative imagery in the archaeological record, from at least around that period), this capability must have appeared in one human (because it involved a mutation) at some point back then. And it must have occurred full blown.

Since he conceives language as a function that enhances thought rather than communicative ability (he construes the latter entirely in terms of animal signaling which he, quite strangely, thinks optimal for communication among species members without involving the animal's mental life), he argues that this suddenly appearing human mutation in a single early human could not, in the absence of others with the same brain mutation, have developed into language as such, for lack of others to prompt the development of the requisite externalization, through physical behaviors, of the inner computational mechanism which alone, he claims, powers all actual human languages.

Because he construes natural human languages as externalizations of this posited inner mechanism (which, on his view, is thought-relevant, not communication-directed), he downplays or ignores the communicative role of language, itself, along with the evolutionary advantages that could have helped in the development of a language mechanism for creatures initially lacking in that inner computational capacity. Recognizing such advantages would imply a gradual development of language rather than a sudden appearance of an inner mechanism as he posits which ultimately finds external expression when enough creatures in the group inherit the trait that makes inner thought modalities possible.

The alternative to his view, that it is the gradual growth of increasingly expansive signaling capabilities (through enhanced brain capacities for collecting, recalling and organizing sensory inputs into recognizable and useful patterns) which allows the development of language, and, through language, expanded thinking capacity, is rejected. Instead he argues that human languages ride on his posited inner mental "language" that must pre-exist actual expressed human languages.

Having no external pressures on the thinking capacity he takes to be required to enable language in humans -- because he imagines it to have arisen all at once in a single proto-human -- evolution (as in natural selection) could not have been involved in its appearance. Thus, he claims, the only explanation for the occurrence of language in the human species as well as individually in each individual member of that species through maturation, must be that the capacity for language sprang full-blown in our ancestors and found external expression, as the myriad of natural human languages we know, only when enough descendants of that first mutated individual formed a community of individuals possessing that same, genetic mutation. Only then would the externalization of inner thought enabled by the mutation have been able to find external expression through physical activities and so become the languages we encounter in all human groups. Like a "snowflake," he argues, the computational mechanism of discursive thought would have had to form in all its completeness entirely as a result of its own intrinsic nature, at once perfect and fully shaped, rather than through the cumulative effects of external factors on whatever substance it consists of.

That is, this computational generative capacity, which he conceives as the core of any possible language, would have had to appear all at once even though, to become language, it would have to wait for a community, derived from the offspring of the first human with this capacity, to begin to connect the internal mental goings on in such creatures with the sensory-motor systems needed to take thought from being an entirely internal capacity to what we recognize as language in all its future iterations in different human communities. His basic thesis is that ANY language, to be that, must rest on a core of an already fully developed language capability (the deep generative grammar which, he argues, is necessary for any language to occur).

In this, he suggests a fundamental discontinuity between the extensive social signaling of members of various primate groups, part of the continuum of all animal signaling activities, and human languages which, he asserts have thinking and thought generation as their prime function rather than communication with other human beings (which he restricts to signaling modalities, however complex, in different animal groups). In other words, language, on this view, cannot be an evolutionary outgrowth of human signaling, however complex, but a radically and fundamentally different sort of capacity.

Yet given the evidence that some non-human primates (chimps, bonobos, gorillas) can be taught both rudimentary human sign language and use of pictures as symbols for communication purposes, along with the fact that there is abundant evidence that many primates DO engage in complex signaling in their natural state, and the further fact that we can detect increasingly sophisticated development of signaling capacities as we move up the evolutionary ladder, is he not disregarding evidence against his thesis, i.e., evidence that suggests language use DOES arise from signaling capabilities?

If it does, then a radically different explanation is called for, i.e., that language is an evolutionary development of signaling capacities which occurred gradually and over a lengthy period of time because of the advantages signaling connected to mental images conferred upon those capable of that compared with their competitors. What kind of advantage? Well isn't the capacity to conceive of and thus depict a world in all its variations and dangers more advantageous for the early human attempting to cross a river in which crocodiles or other hazardous creatures may dwell than just the ability to pick up inklings of a threat and act in ways which alert fellow humans may respond to in ways appropriate to preserving their own lives? If a dog or an ape with only the limited signaling capabilities that allow their fellows to sense danger in the air by reacting to their reactions attempts a river crossing where the crocodile lurks, that creature and its fellows are limited in their ability to plan or anticipate or even comprehend the nature of the threat.

But language using creatures like ourselves can talk about our world and share information (and an understanding the nature of the threat) in a way that is unavailable to the non-language capable creature at the river's edge. And this can be done not only at the moment of crossing but in advance of that, in recognition of what rivers and crocodiles are and how they may be found together. Long term planning and even complex responses when the possibility of longer term planning isn't available, are made possible for language users while remaining unavailable to creatures dependent on instinct and expressive behaviors qua signaling alone. So language looks to have a foundation in signaling capabilities and is thus construable as an evolutionary extension of more basic signaling capacities as seen in other creatures. But if this is the case, then language need not have sprung full blown as an internal mutation in the brain at all but, rather, could have developed along with the gradual increase in brain size and capacities capable of applying signaling in increasingly complex ways, i.e., in order to connect behaviors (whether verbal or otherwise) with the mental imaging that occurs when brains take in sensory information and retain such information in relational ways (as recognizable patterns that are associated with other patterns, etc.).

This may not fully answer Chomsky's challenge regarding how children learn their parents' language so rapidly and spontaneously, despite its significant complexity (whose rules they cannot be fully exposed to before learning to make use of them), but it does address the other oddities of his account:

1) That discursive thought must somehow precede linguistic facility (even though language seems essential to the occurrence of discursive thought); and

2) That evolution, i.e., the forces of natural selection, can have played no role in the development of the internal mechanism of generative computation which, he avers, alone makes language possible.

His account depends on positing a single complex capacity, spontaneously occurring in a human ancestor by mutation, without further alteration, that enables humans to think before they can speak. But both the complexity of the posited mechanism and the fact that thinking in complex ways without language, as a means for organizing information in discursive ways, are hard to explain as spontaneously occurring, argue against this account. A better one, though still incomplete because some issues remain unexplained, is an evolutionary one that sees language development as gradual, a function of evolutionary pressures -- and discursive thought as a matter of co-development with language.