Bob Berwick recently sent me something that aims to survey,
albeit sketchily, the state of play in the evolution of language (evolang) and
a nice little paper surveying the current state of Gould and Lewontin’s
spandrels paper (here)
(hint: their warning is still relevant). There have also been more than a few
comments in FOL threads remarking on the important progress that has been made
on evolang. I believe that I have invited at least one evolang enthusiast to
blog about this (I offered as much space as desired, in fact) so as to
enlighten the rest of us about the progress that has been made. I admit that I
did this in part because I thought that the offer would not be taken up (a put
up or shut-up gambit) and also (should the challenge be accepted) because I
would really be interested in knowing what has been found given my profound
skepticism that at this moment in time there is anything much to find. In other words, for better or for worse,
right now I doubt that there is much substantive detail to be had about how
language actually evolved in the
species.[1]
In this regard, we are not unlike the Paris Academy over a century ago when it
called for a moratorium on such speculation.
That said, who can resist speculating? I can’t. And
therefore, this post was intended to be an attempt to examine the logic of an
evolution of language account that would satisfy someone like me. I wanted to do
this, because, though close to vacuous most of the discussion I’ve seen is
(like the fancy inversion here?), I think that Minimalism has moved the
discussion one small conceptual step forward. So my intention had been to
outline what I think this small step is as well as point to the considerable
distance left to travel.
As you can tell from the modal tenses above, I was going to
do this, but am not going to do it. Why not? Because someone has done this for
me and instead of my laying out the argument I will simply review what I have
received. The text for the following sermon is here,
a recent paper by Chomsky on these matters.[2]
It is short, readable and (surprise, surprise) lays out the relevant logic very
well. Let’s go through the main bits.
Any discussion of evolang should start with a
characterization of what features of language are being discussed. We all know
that “language” is a very complex “thing.” Any linguist can tell you that there
are many different kinds of language properties. Syntax is not phonology is not
semantics. Thus in providing an evolutionary account of language it behooves a
proposal to identify the properties under consideration.
Note that this is not an idiosyncratic request. Evolution is
the study of how biological entities and capacities change over time. Thus, to
study this logically requires a
specification of the entity/capacity of interest. This is no less true for the
faculty of language (FL) than it is for hearts, kidneys or dead reckoning. So,
to even rationally begin a discussion in evolang requires specifying the properties
of the linguistic capacity of interest.
So, how do we specify this in the domain of language? Well,
here we are in luck. We actually have been studying these linguistic capacities
for quite a while and we have a rich, developed, and articulate body of
doctrine (BOD) that we can pull from in identifying a target of evolutionary
interest. Chomsky identifies one feature that he is interested in. He terms
this the “Basic Property” (BP) and describes it as follows:
[E]ach language yields a digitally
infinite array of hierarchically structured expressions with systematic
interpretations at interfaces with two other internal systems, the sensorymotor
system for externalization and the conceptual system, for interpretation,
planning, organization of action, and other elements of what are informally
called “thought.” (1)
So one evolang
project is to ask how the capacity
that delivers languages with these properties (viz. I-languages) arose in the
species. We call the theory of I-languages “Universal Grammar” or UG as it
“determines the class of generative procedures that satisfy the Basic Property”
(1). We can take UG as “the theory of the genetic component of the faculty of
language.” If we do, there is a corresponding evolang question: how did UG
arise in the species?[3]
Note, that the above distinguishes FL and UG. FL is the
mental system/”organ” that undergirds the human linguistic competence (ie. The
capacity to develop (viz. “grow”) and deploy (viz. “use”) I-languages). UG is
the linguistically specific component
of FL. FL is likely complex, incorporating many capacities only some of which are linguistically proprietary.
Thus, UG is a subpart of FL. One critical evolang question then is how much of
FL is UG. How much of FL consists of linguistically proprietary properties,
capacities/primitives that are exclusively linguistic?
Why is the distinction important? Well, because it sure
looks like humans are the only animals with BP (i.e. nothing does language like
humans do language!) and it sure looks like this capacity is relatively
independent of (viz. dissociates with) other cognitive capacities we have (see here).
Thus, it sure looks like the capacity to generate BP-I-languages (BPIs) is a
property of humans exclusively. And now we come to the interesting evolang
problem: as a point of evolutionary logic (we might dub this the Logical
Problem of Language Evolution (LPLE)) the
bigger the UG part of FL, the more demanding the problem of explaining the
emergence of FL in the species. Or as Chomsky puts it (3): “UG must meet the
condition of evolvability, and the more complex its assumed character, the
greater the burden on some future account of how it might have evolved.”
We can further sharpen the evolvability problem by noting
one more set of boundary conditions on any acceptable account. There are two relevant
facts of interest, the first “quite firm” and the second “plausible” and that
we refer to with “less confidence.”
These are:
1. There
has been no evolution of FL in the species in the last 50k years or more.
2. FL
emerged in the way it exists today about 75k years ago.
As Chomsky puts it (3): “It is, for now, a reasonable
surmise that language –more accurately UG- emerged at some point in the very
narrow window of evolutionary time, perhaps in the general neighborhood of 75
thousand years ago, and has not evolved since.”[4]
Why is (1) firm? Because there are no known group
differences in the capacity humans have in acquiring and using a natural
language. As the common wisdom is that our ancestors left Africa and their paths
diverged about 50kya then this would be unexpected were there evolution of FL
or UG after this point.
Why is (2) less firm? Because we infer it to be true based
on material cultural artifacts that are only indirect indicators of linguistic
capacity. This evidence has been reviewed by Ian Tattersal (here)
and it looks like the conclusion he draws on these issues is a plausible one.
Chomsky is here relying on this archeological “consensus” view for his
“plausible” second assumption.
If these assumptions are correct then, as Chomsky notes (3) “UG must be quite simple at its core” and it
must have emerged more or less at once. These are really flip sides of the same
claim. The evolutionary window is very narrow and so whatever happened must
have happened quickly in evo-time and for something to happen quickly it is
very likely that what happened was a small simple change. Complexity takes a
long time. Simplicity not so much.[5]
So, what we are looking for in an evolang account of our kinds of natural
langauges is some small change that has BPI-effects. Enter Minimalism.
Chomsky has a useful discussion of the role of evolvability
in early Generative Grammar (GG). He notes that the evolvability of FL/UG was
always recognized to be an important question and that people repeatedly
speculated about it. He mentions Lenneberg and Luria in this regard, and I
think I recall that there was also some scattered discussion of this in the Royaumont
conference. I also know that Chomsky discussed these issues with Francois Jacob
as well. However, despite the interest of the problem and the fact that it was
on everyone’s radar the speculation never got very far. Why not? Because of the
state of the theory of UG. Until
recently, there was little reason for thinking that UG was anything but a very
complicated object with complex internal structure, many different kinds of
primitives, processes and conditions (e.g. just take a look at GB theory).
Given the LPLE, this made any fruitful speculation idle, or, in Dwight
Whitney’s words quoted by Chomsky: “The greater part of what is said and
written about it is mere windy talk” (4) (I love this Ecclesiastical
description: Wind, wind, all is wind!).
As Chomsky notes, minimalism changed this. How? By
suggesting that the apparent complexity of UG as seen from the GB angle (and
all of GB’s close relatives) is eliminable. How so? By showing that the core
features of BPIs as described by GB can be derived from very a simple rules (Merge)
applied in very simple ways (computationally “efficient”). Let me say this more
circumspectly: if to the degree that
MP succeeds to that degree the apparent complexity of FL/UG can be reduced. In
the best case, the apparent complexity of BPIs reduces to one novel language
specific addition to the human genome and out falls our FL. This one UG addition together with our
earlier cognitive apparatus and whatever non-cognitive laws of nature are
relevant suffice to allow the mergence of the FL we all know and love. If MP can cash this promissory note,
then we have taken a significant step towards solving the evolang problem.
Chomsky, of course, rehearses his favorite MP account (7-9):
the simplest Merge operation yielding unordered merges, the simplest
application of the rule to two inputs yielding PS rules and Movement, natural
computational principles (not specific to language but natural for computation
as such) resulting in conditions like Inclusiveness and Extension and something
like phases, the simple merge rule yielding a version of the copy theory of
movement with obvious interpretive virtues etc.
This story is well known, and Chomsky rightly sees that if something
like this is empirically tenable then it can shed light on how language might have evolved, or, at the very
least, might move us from windy discussions to substantive ones.
Let me say this one more way: what minimalism brings to the
table is a vision of how a simple addition
might suffice to precipitate an FL like the one we think we have empirical
evidence for. And, if correct, this is, IMO, a pretty big deal. If correct, it
moves evolang discussion of these linguistic properties from BS to (almost) science,
albeit, still of a speculative variety.
Chomsky notes that this does not exhaust the kinds of
evolang questions of interest. It only addresses the questions about generative
procedure. There are others. One important one regards the emergence of our
basic lexical atoms (“words”). These have no real counterpart in other animal
communication systems and their properties are still very hard to describe.[6]
A second might address how the generative procedure hooked up to the
articulatory system. It is not unreasonable to suppose that fitting FL snugly
to this interface took some evolutionary tinkering. But though questions of
great interest remain, Chomsky argues, very convincingly in my view, that with
the rise of MP linguistics has something non-trivial to contribute to the
discussion: a specification of an evolvable FL.
There is a lot more in this little paper. For example, Chomsky
suggests that much of the windiness of much evolang speculation relates to the
misconceived notion that the natural language serves largely communicative ends
(rather than being an expression of thought). This places natural languages on
a continuum with (other) animal communication systems, despite the well-known huge
apparent differences.
In addition, Chomsky suggests what he intends with the
locution ‘optimal design’ and ‘computationally efficient.’ Let me quote (13):
Of course, the term “designed” is a
metaphor. What it means is that the simplest evolutionary process consistent
with the Basic Property yields a system of thought and understanding [that is
sic (NH)] computationally efficient since there is no external pressure
preventing this optimal outcome.
“Optimal design” and “computational efficiency” are here
used to mean more or less the same thing. FL is optimal because there is no
required tinkering (natural selection?) to get it into place. FL/UG is thus evolutionarily optimal. Whether this makes it computationally
optimal in any other sense is left open.[7]
Let me end with one more observation. The project outlined
above rests on an important premise: that simple phenotypic descriptions will
correspond to simple genotypic ones. Here’s what I mean. Good MP stories
provide descriptions of mental mechanisms, not
neural or genetic mechanisms. Evolution, however, selects traits by
reconfiguring genes or other biological hardware. And, presumably, genes grow
brains, which in turn secrete minds. It is an open question whether a simple
mental description (what MP aims to provide) corresponds to a simple brain
description, which, in turn, corresponds to a simple “genetic” description. Jerry
Fodor describes this train of assumptions well here.[8]
…what matters with
regard to the question whether the mind is an adaptation is not how complex our
behaviour is, but how much change you would have to make in an ape’s brain to
produce the cognitive structure of a human mind. And about this, exactly
nothing is known. That’s because nothing is known about how the structure of
our minds depends on the structure of our brains. Nobody even knows which brain
structures it is that our cognitive capacities depend on.
Unlike our minds, our
brains are, by any gross measure, very like those of apes. So it looks as though
relatively small alterations of brain structure must have produced very large
behavioural discontinuities in the transition from the ancestral apes to us…
…In fact, we don’t know what the scientifically
reasonable view of the phylogeny of behaviour is; nor will we until we begin to
understand how behaviour is subserved by the brain. And never mind
tough-mindedness; what matters is what’s true.
In other words, the whole evolang discussion rests on a
rather tendentious assumption, one for which we have virtually no evidence;
namely that a “small” phenotypic change (e.g. reduction of all basic
grammatical operations to Merge) corresponds to a small brain change (e.g. some
brain fold heretofore absent all of a sudden makes an appearance), which in
turn corresponds to a small genetic change (e.g. some gene gets turned on
during development for a little longer than previously). Whether any of this is correct is anyone’s
guess. After all there is nothing incoherent in thinking that a simple genetic
change can have a big effect on brain organization, which in turn corresponds
to a very complex phenotypic difference. The argument above assumes that this
is not so, but the operative word is “assume.” We really don’t know.
There is another good discussion of these complex issues in
Lenneberg’s chapter 6, which is worth looking at and keeping in mind. This is
not unusual in the evolution literature, which typically assumes that traits
(not genes) are the targets of selection. But the fact that this is commonly the
way that the issues are addressed does not mean that the connections assumed
from phenotypic mental accounts to brains to genes are straightforward. As
Fodor notes, correctly I believe, they are not.
Ok, that’s it. There is a lot more in the paper that I leave
for your discovery. Read it. It’s terrific and provides a good model for
evolang discussions. And please remember the most important lesson: you cannot describe the evolution of
something until you specify that thing (and even then the argument is very
abstract). So far as I know, only linguists have anything approaching decent
specifications of what our linguistic capacities consists in. So any story in
evolang not starting from these kinds of specifications of FL (sadly, the
standard case from what I can tell) are very likely the windy products of
waving hands.
[1]
Happily, I have put myself in the good position of finding out that I am wrong
about this. Marc Hauser is coming to UMD soon to give a lecture on the topic
that I am really looking forward to. If there are any interesting results, Marc
will know what they are. Cannot wait.
[2]
I’d like to thank Noam for allowing me to put this paper up for public
consumption.
[3]
Please observe that this does not imply that BP is the only property we might
wish to investigate, though I agree with Chomsky that this is a pretty salient
one. But say one were interested in how the phonological system arose, or the
semantic system. The first step has to be to characterize the properties of the
system one is interested. Only once this is done can evolutionary speculation
fruitfully proceed. See here
for further discussion, with an emphasis on phonology.
[4]
It is worth noting that this is very fast in evolutionary terms and that if the
time scale is roughly right then this seems to preclude a gradualist
evolutionary story in terms of the slow accretion of selected features. Some
seem to identify evolution with natural selection. As Chomsky notes (p. 11),
Darwin himself did not assume this.
[5]
Furthermore, we want whatever was added to be simple because it has not changed
for the last 50k years. Let me say this another way: if what emerged 100kya was
the product of slow moving evolutionary change with the system accreting
complexity over time then why did this slow change stop so completely 50kya?
Why didn’t change continue after the trek out of Africa? Why tones of change
before hand and nothing since? If the change is simple, with not moving parts,
as it were, then there is nothing in the core system to further evolve.
[6]
I’ll write another post on these soon. I hope.
[7]
If this reading of Chomsky’s intention here is correct, then I have interpreted
him incorrectly in the past. Oh well, won’t be the last time. In fact, under
this view, the linguistic system once evolved need not be particularly
efficient computationally or otherwise.
On this view, computationally efficient seems to me “arose as a matter
of natural law without the required intervention of natural selection.”
[8]
The relevant passage is
