In a recent paper (here), Tecumseh Fitch (TF) and colleagues argue that monkey vocal tracts are structurally adequate for the production of human speech sounds. Why is this important? Because, as the paper puts it:
Our findings imply that the evolution of human speech capabilities required neural changes rather than modifications of vocal anatomy. Macaques have a speech-ready vocal tract but lack a speech-ready brain to control it.
This, in other words, puts another nail in the coffin of those that look to provide a continuity thesis style of explanation of human linguistic facility based on a quantitative extension of what appears in our nearest cousins (i.e. If this is right it then Phil Lieberman was wrong). If TF is right, then all that effort expended in trying to teach primates to speak was a waste of time (which it was) and the failure was not one that could be resolved by teaching them sign (which in fact didn’t help) because the problem was neural not vocal. IMO, the futility of this line of inquiry has been pretty obvious for a very long time, but it is always nice to have another nail in a zombie’s coffin.
The results are interesting for one other reason. It suggests that Chomsky’s assumption that externalization is a late add-on to linguistic competence is on the right track. FT provides evidence that vocalization of the kind that humans have is already in place engineering wise in macaques. Their vocal tracts have the wherewithal to produce a range of vowels and consonants similar to those found in natural language. If they don’t use this to produce words and sentences (or movie reviews or poems) it is not because they lack the vocal tract structure to do so. What they lack is something else, something akin to FL. And this is precisely Chomsky’s suggestion. Whatever changed later coupled with an available system of externalization. This coupling of the new biologically unique system with the old biologically speaking more generally available system was bound to be messy given they were not made for each other. Getting the two to fit together required gerrymandering and thus was born (that messy mongrel) morpho-phonology. FT supports this picture in broad outlines.
One more point: if externalization follows the emergence of FL, then communication cannot be the causal root of FL. Clearly, whatever happened to allow FL to emerge came to take advantage of an in-place system capable of exploitation for verbal communication. But it seems that these capacities stayed fallow language wise until the “miracle” that allowed FL to emerge obtained. On the assumption that coupling FL with an externalization mechanism took time, then the selective pressure that kept the “miracle” from being swept away cannot have been communicative enhancement (or at least not verbal communicative enhancement). This means that Chomsky-Jacob suggestion (here) that the emergence of FL allowed for the enhancement of thought and that is what endowed it with evolutionary advantage is also on the right track.
All in all, not a bad set of results for MP types.