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Monday, September 1, 2014

A concise discussion of Darwin's Problem

A bunch of the good guys (Bolhuis, Tattersall, Chomsky and Berwick (BTCB) have a new paper out in Plos Biology that reviews in a concise manner the logic relating the Minimalist Program (MP) and Darwin’s problem (DP). The paper is worth knowing about for several reasons, not the least being that it came out in Plos Biology, an important venue for bio research. It also is a nice short paper that one can give to friends (I in fact just sent it to an econ buddy of mine) if they are curious about what kinds of BIG issues linguists are trying to address.

For the cognoscenti, the discussion will be quite familiar (though if you are like me and love greatest hits albums, this will be a pleasure to read). It starts where all good evo discussions have to start; with a characterization of the faculty whose emergence one is interested in explaining). BTCB hits all the required notes: language is not speech, nor an instrument for communication. Or, more precisely, externalization is not relevant to the key features the “language faculty per se” (1).  Rather (and get ready for the surprise), “language is a computational cognitive mechanism that has hierarchical syntactic structure at its core…” (1). In other words, the target of evo explanation in the domain of language is how this generative capacity came to be fixed as a biological property of humans. [1]

With the target of explanation specified, BTCB goes on to make the observation that MP has the properties required to allow an assault on this problem. What the paper does not say (but I think is important), is that prior to the emergence of MP linguists had little to contribute (or more accurately, little they could contribute) to the question of how FL evolved. How does MP advance the evo issues? By providing “an extremely simple” account of human syntax, “simple” being the key feature.  In other words, what MP affords (or, at least, promises) is a characterization of syntax as comprising a single simple combinatoric operation, which, when combined with the “general cognitive requirement for computationally minimal or efficient search,” “suffices to account for much of human language syntax” (p. 1-2).  In other words, what MP does is so simplify the structure of FL that it makes it possible to understand how an FL with these characteristics might have come into being. Or, to put this another way, prior to MP the understood structure of FL was so complex and sui generis (had so many moving and interacting parts) that it was impossible to see how it could have evolved.  In short, the only hope we have of providing an account of how FL arose in the species is if FL has an MPish structure. Note, that this is very much a conceptual argument. Evo details, as BTCB notes, will be very hard to come by, as they note and we return to anon.

BTCB proceeds to observe two nice features (consequences?) of a simple FL: (i) it could have emerged all at once, and (ii) it would have remained stable given its lack of moving parts. As BTCB note, there is evidence that both these features are correct.

The second (viz. that FL has remained largely unchanged since its emergence) is almost certainly correct as “there is no doubt that a normal child from England raised in northern Alaska would readily learn Eskimo-Aleut, or vice versa” (p. 2). In other words, so far as we can tell all humans (even those from isolated communities) share a common FL as witnessed by the fact that any human can learn any language if properly environmentally situated. As BTCB notes, the uniformity and stability of FL “points to the absence of major evolutionary change since the emergence of the language faculty” (2). It also, IMO, supports the idea that FL is not itself the end-product of selection for if it were we might expect to see continuing differential changes in FL’s structure, with different groups having slightly different FLs facilitating the use and acquisition of some languages at the expense of others. We, apparently, do not see this, which suggests that all FLs are of a piece, which would make sense if they were very simple in an MPish sort of way.

Let’s now turn to the issue of rapid emergence. Finding evidence relevant to making evo claims turns out to be very (very very very…) difficult, with the available evidence being “quite indirect.” BTCB reiterates a point made by Lewontin long ago (here) that getting non-trivial evidence that bears on the issues is not at all easy. In fact, BTCB identifies exactly one kind of useful type of evidence for dating the emergence of “language,” and it comes from archeology. The evidence is the sudden widespread explosion of symbolic artifacts in the archeological record roughly 100 thousand years ago. These artifacts have been used as “proxies” for language, the idea being that the emergence of language (and the cultural evolution it supports?) is the main causal factor behind this sudden rise in symbolic artifacts. This, BTCB emphasizes is “quite indirect” evidence for the presence of a fully operational FL, but it is all we’ve really got given the exigencies of finding the standard kinds of relevant evidence commonly used to advance reasonable evo hypothesizing (again, see Lewontin on this for an elaborate and useful review). This archeological evidence (which I assume that Tattersall is responsible for reviewing here) points to a relatively rapid emergence of FL about 100kya (p. 3). The artifact-proxies for language emerge in the archeological record all at once, in many places and quickly. It suggests that whatever took place did not happen gradually (contra many standard Darwinian tropes). Note, the possibility of rapid emergence is conceivable if what made it possible is a simple addition to an otherwise available system, the kind of system MP aims to provide.

To wrap up: BTCB has two important virtues: (i) It illustrates the strong conceptual bond between MP and DP, and (ii) it illustrates how meager the actual data bearing on evo concerns in the domain of language really are. As a matter of facts we still know next to nothing about how FL emerged. Moreover, we are unlikely to learn anything in the near future about the details given how hard it will be to find relevant evidence bearing on the issue. Nonetheless, BTCB shows that some progress has been made, but mainly from the linguistic/conceptual side. I think that BTCB is right in thinking that MP is a conceptually important move forward, as any conceivable account of the mergence of FL will require something like MP. So if you are Darwin enchanted then you’d better become a card- carrying minimalist. It’s the only hope, even if it is a faint one.






[1] The paper also makes some nice methodological observations concerning what an evolutionary account can and cannot hope to deliver. BTCB observe that as a matter of logic, evo accounts cannot deliver explanations of how what has evolved actually works.  This is why a grammatical characterization of FL is so vital. Evo accounts need specifications of mechanisms. Specifications of mechanism can proceed quite happily without evo accounts of how they got there.  For further discussion of this point, see the Bolhuis and Wynne paper referred to in the notes. It’s worth a read.

9 comments:

  1. This story a) says nothing about the feature machinery you need to get Merge to work properly b) no discussion of the issue of how animals organize their behavior, some of which (forex nestbuilding) involves complexities such as subgoals, or how they parse the behavior of other animals, of same or different species, to figure out what they're up to. The two aspects of b) are a prima facie plausible source of preadaptations to language that might help with DP.

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    1. Good questions, Avery. Re a) presumably the innate concepts we allegedly all share have to do most of the explanatory work. Your comments on Nativism, Rationalism and Empiricism-1 suggest you're not quite satisfied, but give Norbert a chance, maybe by the time we get to Nativism, Rationalism and Empiricism-4444 he has told us the full story.

      Your b) shows that you are still in the grip of pre-minimalist thinking. But, you see, Chomsky's evolutionary theorizing has greatly advanced since then. The new dogma is that "it is conceivable that ‘some random event [maybe some strange cosmic ray shower] causes a language faculty to be installed in [a primate] . . . In fact it is conceivable ... that higher primates, say gorillas or whatever, actually have something like a human language faculty but just have no access to it’ (Chomsky 2000: 16–17). So no need to worry about pre-adaptations in other species, of course they have them, even fully installed LFs minus Merge. If you own the wondrous volume "Of Minds and Language" you may want to consult Juan Uriagereka's chapter [esp. 178-179] for an advanced application of this kind of thinking.

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    2. @Avery:
      Yes, there are many things that the paper does not deal with. But as I read it, the argument is aimed at necessary conditions evo accounts, not sufficiency. The argument is that given the very little that we know about the emergence of FL, it had better be true that something like MP is on the right track; viz. that FL is the product of a very simple addition in the context of otherwise cognitively general computational principles. They add that there is reason to think that this is true given the stability of FL since its inception and its sudden emergence. As you note there are still many problems to be addressed. The most important one is, IMO, the source of our forms of lexical items. They are very complex and quite different from what we find in other animals, so how'd they get there?

      Re your plausible sources of pre-adaptations: I agree here as well. I've even tried to make suggestions regarding the useful sub computations. But putting this aside, I think that we need some rough sketches of how this might proceed. I'm not asking for whole stories, but rough sketches. So far as I know, if one's interest is in the kind of recursion we find in language, then there are no other systems like it, a point made in the BTCB paper. So if this is what one takes to be a distinctive property (And I do) then it appears that pre-adaptations will have little to say. If one looks at another property, things might be different. The project should be to identify the property of interest and then provide a sketch trying to explain how it could have emerged. I suspect we will end up with the distinction between wide and narrow FL again, not a bad place to end up as it seems like a reasonable first cut at the issue.

      So, you are right: there are still many steps of the program to be filled in. However, the link between DP and MP seems reasonably well argued. The real question is not a conceptual one, but whether MP can make good on its promises and what else we might need to add to the mix.

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    3. Fair enough. But, to be a proper respectable scientific theory, you have to have defeated some worthy enemies, & nobody yet knows enough about complex animal behavior to put one together as a competitor to the emergence of Merge. But, it is possible to get apparent syntax without Merge - a Rodney Brookes student called Penelope Sibun write a language generator that produced house layout and family descriptions by navigating graphs .. all you have to be able to do is store the graph, and have a method for traversing it and spitting out words. & for this to be useful for communication, the hearers need to be able to reconstruct the graph from the words.

      Orangutans seems to have some fairly sophisticated route-planning abilities, and communicate about them to some extent, so maybe that's how it got started ...

      I would probably be less interested in these alternatives if I understood how Merge could be useful without a lot of additional complex feature-managing machinery, because then there would at least be a full team on field, which does not seem to me to be the case ATM.

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    4. @ Avery: You write "nobody yet knows enough about complex animal behavior to put one [= a proper respectable scientific theory] together as a competitor to the emergence of Merge."

      Well 'the emergence of Merge' isn't exactly a scientific theory. It is a speculation that one mutation occurred in one person some 50,000 to 100,000 years ago. It is not even clear what this mutation resulted in. Sometimes we read about 'rewiring of the brain' [but never any before-after comparison is offered], sometimes Merge is a computational structure [which has never been given any biophysiological description]. You really have to pause for a moment and think about this: someone who claims to explore the biology of language and that Merge [a product of a mutation] is the essential operation of language spends absolutely NO time working on the biology of Merge. So as far as scientific theories go the Merge miracle certainly is no contender...

      You say yourself that it is difficult to see how "Merge could be useful without a lot of additional complex feature-managing machinery" and BTCB certainly has nothing to say about that. In fact this paper says nothing new but seems one more effort to 'establish truth by repetition': if you say something often enough eventually people will believe it is true.

      One more thing: given that Fodor titled one of his contributions "What Darwin got wrong" we should stop calling whatever Norbert or BTCB claim to explore "Darwin's Problem" and call it by its proper name "Chomsky's Problem".

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    5. I guess I was just responding to what I took to be the immediate point of Norbert's comment, rather than tipping the entire bucket. That some capacity to put together complex structures without a lot of support from the appearance of the immediate environment was an important innovation strikes me as a reasonable humanistic/literary speculation; to turn it into science we just need a lot more in the way of additional information.

      One thing I'd like to know is whether the clever crows that can get the tool to get the tool to get the treat can do all this if the devices they have to operate are scattered around in unpredictable locations in an environment without a lot of visual connectivity, so they would have to use internal representations to keep track of what they were doing in order to succeed. If they failed under these conditions, that show that their internal representations suffer from serious limitations relative to ours.

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  2. What a nice demonstration of how one should not think about biological evolution. The comments space is limited so just a few short observations:

    1. "what MP does is so simplify the structure of FL that it makes it possible to understand how an FL with these characteristics might have come into being. Or, to put this another way, prior to MP the understood structure of FL was so complex and sui generis (had so many moving and interacting parts) that it was impossible to see how it could have evolved".

    By this logic things that are complex and have many moving parts [like say the human eye] could not have evolved. Yet humans have eyes - surely a miracle.

    2. "the uniformity and stability of FL “points to the absence of major evolutionary change since the emergence of the language faculty” (2). It also, IMO, supports the idea that FL is not itself the end-product of selection for if it were we might expect to see continuing differential changes in FL’s structure, with different groups having slightly different FLs facilitating the use and acquisition of some languages at the expense of others. We, apparently, do not see this, which suggests that all FLs are of a piece, which would make sense if they were very simple in an MPish sort of way."

    One wonders why this one piece FL is NOT subject to random mutation, genetic drift or any other force that affects all other biological traits that are not under selectional pressure. What kept FL constant over the millenia in say Pirahas [assuming they do really not use Merge]? Would not matter to them if some/all of them had mutated LFs. But no, they don't - a second miracle...

    3. "BTCB identifies exactly one kind of useful type of evidence for dating the emergence of “language,” and it comes from archeology. The evidence is the sudden widespread explosion of symbolic artifacts in the archeological record roughly 100 thousand years ago".

    Running out of space, so I just refer the reader to http://ling.auf.net/lingbuzz/001592 , section 3.1, especially discussion on pp.14-15, showing the problems with Norbert's reasoning.

    Last point: I would not make too much of the fact that BTCB has been published in a bio-journal. After all, a linguistics journal [JL] published my review article of SoL, and we all know what Norbert thinks about THAT ..

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  3. I want to present a new approach that is based on work outlined in my recent post in the Computation etc. thread. There I described a newly-identified small set of semantic features derived from the lexicon. I call these ‘semantic factors’. They are unlike other proposed types of semantic features in that they effectively self-identify in core words of the lexicon of some languages under a straightforward process. Their empirical credentials are very robust. Key characteristics are their non-linguistic and highly abstract nature, their necessary presence in the structure of word meaning, their ability to account for the structure of meanings in any language, and their innateness.

    As outlined in my other post, the factors apply equally to concepts, cognition, memory, behaviour and experience and they are intrinsically biological. They operate as ‘the dimensions of the space of the interaction of organisms and their environments'. They are formatives of behavior.

    Under this scenario we can assume that the factors were present in the concepts of pre-linguistic hominids long before the appearance of language. Presumably they possessed concepts and combined them in a non-linguistic mental language. Given their biological scope, the factors had the same form and function there as in spoken language. Following this logic a Merge-type function operated long before spoken or gestured language existed and was not responsible for its emergence.

    This pushes the problem back further. What facilitated the emergence of the human mental language with its necessary Merge-type function? A prime precondition was the development of the faculty of displaced conceptualisation, something animals are assumed not to possess. Once hominids were able to form concepts in the absence of their referents there was a need for a combinatory function. It seems reasonable to assume that these developments arose more or less together.

    What sparked the development of language, as we know it? Perhaps (pure speculation) the ferment of thought in individual brains in the innumerable situations that demanded co-operation was sufficient to put hominids on the long road of developing a sign or spoken language. It’s relevant that the factors are eminently suitable for iconic representation. It is widely recognised now that iconicity is pervasive in the languages of the deaf. I have found it pervasive also in some spoken languages including English. The factors are eminently suitable for iconic representation as in size symbolism. This may have facilitated the breakthrough.

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