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.
