Humans are uniquely linguistically facile. This raises an interesting evolutionary question, an abstract version of which Minimalists have taken very much to heart: How did this linguistic capacity arise in the species? Following Cedric Boeckx, let’s dub this “Darwin’s Problem.” Answers to this problem have two separable parts: (i) an account of how that which made language a cognitive option became mentally available, (ii) an account of how the available option became fixed in the species.
Most give a “miracle theory” account of (i). What I mean is that it is regularly assumed that some kind of adventitious genetic change/mutation occurred that, when added to the cognitive apparatus already there, combined with it to allow for the emergence of a mental faculty with the key features of FL. The “miracle” means to mark the observation that this change “just happened,” it’s a brute fact. Minimalists try to (abstractly) characterize the nature of this change (what was added), but that there is no attempt to explain why the change occurred. It just did. What’s up for grabs is the nature of the change (adding Merge being the currently favored candidate, though there have been other proposals, (one by yours truly)) and the number of these. Given the logic of the case (short time span etc.), one miracle is acceptable, two maybe barely tolerable, three fougetaboutit! At any rate, a miracle occurred sometime in the last (roughly) 100,000 years in at least one member of the species. This brings us to (ii).
Once the miracle occurs, it must be fixed in the population, presumably by giving its bearers some selective advantage (this is the Darwin part). With respect to language there are basically two possible sources for this advantage, which correspond with two classical views about the utility of language; language as vehicle for communication and language as vehicle for thought. Pinker and Bloom are perhaps the most famous advocates of the first conception. Chomsky is a well-known advocate of the second.
There are two main problems with the communication view.
First, it requires double the number of miracles. Note, this follows from two observations: that it takes at least two to communicate and mutations (the required miracle) originate in individuals and spread to populations via the reproductive success of the favored individuals. Thus, as improbable is it is for Merge, say, to pop into an individual ape mind once the chances of it doing so twice in two different (assuming that communication is between at least two individuals) proximate (if not near each other than the capacity to communicate won’t be realized) individuals, is much much more improbable still. Indeed if the events are independent, then it’s the square of the probability of the unique event.
Second, we need a story about why the particular form of communication, a communication system based on Merge like grammars, is so much more advantageous than a simpler system would be. Here’s what I mean. Consider a simple linear N-V-(N) grammar with a vocabulary of 500 verbs and 1,000 nouns. This can support roughly 500,000,000 different messages. That’s a good number of messages, all without hierarchical recursion. We know that animal communication doesn’t require recursion. The evolutionary question then is what communicative advantage does the miracle promote that would be particularly advantageous?
Considerations like these led many to conclude that the main selective advantage of language was its enrichment of thought rather than its communicative efficacy. Here’s Francois Jacob’s take:
…the role of language as a communication system between individuals would have come about secondarily…Its primary function would rather have been, as with earlier evolutionary steps in mammals, the representation of a finer and “richer” reality,” a way of handling more efficiently a greater amount of information. As exemplified throughout the whole animal kingdom, communication can be easily established between individual organisms. Even among hominids which had to hunt and live in community, most of the information to be shared with others and concerning immediate features of life could be handled by means of rather simple codes. In contrast, to translate a visual and auditory world so that objects and events can be precisely labeled and recognized weeks or years later requires a much more elaborate coding system. The quality of language that makes it unique does not seem to be so much its role in communicating directives for action as its role in symbolizing, in invoking cognitive images. We mold our “reality” with our words and our sentences in the same way as we mold it with our vision and our hearing. And the versatility of human language also makes it a unique tool for the development of imagination. It allows infinite combinations of symbols and, therefore, mental creation of possible worlds (58).
Thus, the proposal is that grammatical structures enhance the class of entertainable and easily retrievable of thoughts. It allows for the imagination of alternatives, thereby, one might suppose, enhancing planning and action (as well as making dawdling that much more enjoyable!). At any rate, were this so, then it is not hard to imagine how a miracle that enabled this would immediately endow its individual bearer with the kinds of advantages that natural selection cares about and how, therefore, this miracle could go forth and multiply via its bearers going forth and multiplying.
Before going on, we should appreciate that all of this is speculative. As Lewontin has made clear, there is a big, perhaps ultimately insurmountable, step between this and a serious scientifically grounded selective explanation. As he demonstrates in detail (c.f. his "The Evolution of Cognition" in volume 4 of The Invitation to Cognitive Science), it’s extremely hard to move beyond just-so stories and provide empirically justified evolutionary accounts of cognitive capacities.
This said, there are tantalizing hints and what I want to point to one. I have just reread some fascinating work (from 1999) by Hermer-Vazquez, Spelke and Katsnelson (H-VSK) that bears on these questions. They provide evidence for the kind of scenario that Jacob describes above. Here’s what they found (from the abstract):
Under many circumstances, children and rats reorient themselves through a process which operates only on information about the shape of the environment... In contrast, human adults relocate themselves more flexibly by conjoining geometric and non-geometric information to specify their position. The present experiments used a dual-task method to investigate the processes that underlie the flexible conjunction of information…Together the experiments suggest that humans’ flexible spatial memory depends on the ability to combine divers information sources rapidly into unitary representations and that this ability, in turn, depends on natural language.
The experiments all involve disorienting children and adults in a rectangular room. The task is to find something in a prescribed corner. Sometimes the indicated corner abuts a wall with a certain color, thereby distinguishing it from the geometrically analogous opposite corner. Adults are able to exploit the additional color information to locate themselves and thus to identify the right corner (i.e. color serves to disambiguate the geometrical information). Prelinguistically capable kids cannot. Nor can rats. More interesting still, H-VSK found a way of stopping adults from using the color information by having them engage in a language task while reorienting themselves. Presto, the adults start acting like kids and rats. Importantly, engaging in additional non-linguistic tasks during reorientation does not stop successful identification of the correct corner. This strongly implicates language use in facilitating spatial orientation.
I hope I have piqued your interest. The experiments are a delight to read (so do so) and the implications for Jacob’s (and Chomsky’s) evolutionary scenario very suggestive. Here we have a case where linguistic facility directly enhances something as basic as spatial orientation, a capacity that it does not take much imagination to suppose would be useful to our hunter-gatherer ancestors and would endow selective advantage in a wide range of plausibly relevant environments.
How exactly does language help? H-VSK speculate that language constitutes a kind of interlingua allowing diverse information from separately encapsulated cognitive modules to combine into single thoughts. The capacity to so combine diverse concepts allows for more complex thoughts and thereby allows, in Jacob’s words, for “the representation of a finer and “richer” reality.” In sum, were the Jacob-Chomsky speculation on the right track we might expect to find cognitive enhancement for selectionistically valuable traits, and this seems to be what H-VSK have found. Wow!
Need I say that this is still very speculative? However, though a first step, it is very interesting and fits well with certain other assumptions out there minimalists are sure to find congenial.
First, standard Minimalist theory proposes a strong asymmetry between the two interfaces. Rather than syntax being a pairing of sound (AP) and meaning (CI) (the standard view since Aristotle), it is more accurately thought of as a relation between structure and meaning with sound as an add-on (Chomsky has strongly pushed this line of late). The derivation from lexicon to CI is clean and well designed (e.g. it meets Inclusiveness, Extension and Full Interpretation). The mapping to sound is considerably messier (e.g. does not conform to Inclusiveness). This fits well with the Jacob-Chomsky conception which presumes that the real biological action starts with the generation of complex thoughts that grammar makes available, not spoken outputs, which are a later accretion.
Second, Generative Syntax endorses the autonomy of syntax thesis (AOS). Though AOS has often been misunderstood to assert that there is no relation between the grammar and meaning, it actually means that the primitives and operations of the grammar are independent of the contents of what they are used to express. In particular, syntactic categories, principles and operations to not reduce to semantic ones. Many have taken this to be a serious defect. However, in the context H-VSK’s results it looks like a great design feature. Precisely because the syntax is autonomous it is able to combine information from different encapsulated modules. In other words, autonomy is just the flip side of not being modularly restricted. The intra modular primitives and operations cannot do this, which is what makes it impossible for rats, young kids and linguistically distracted adults from combining different kinds of information (i.e. predicates from different modules). From the present perspective, a more revealing term for the autonomy of syntax might be the inter-modularity of syntax, autonomy being precisely the property we want in a tool required to combine diverse types of thoughts and concepts, ones otherwise confined to specialized cognitively encapsulated modules.
Last, consider hierarchy. The kind of combination H-VSK’s tasks require is one that allows for diverse kinds of information to work together to produce finer and finer descriptions. In other words, we want the capacity to modify, viz. stack adverbs, specify events, combine nouns and adjectives, use sentences to cut down possibilities (e.g. as relativization does) etc. This is the conceptual value added that syntactic hierarchy provides, and it does so in spades.
In sum, the Jacob-Chomsky “conjecture” when combined with a generative syntax with a minimalist flavor has a suggestive tang: it links what is special (viz. recursive hierarchy) with what is plausibly beneficial (viz. the capacity to entertain new and useful thoughts).
One of the novelties of the Minimalist Program has been the elevation of Darwin’s Problem to prominence along side Plato’s. Interestingly, it appears that the empirical just-so stories of yore might finally graduate to empirically so-so stories and, one day maybe even to thus-so stories. Wouldn’t that be nice? Can’t blame a person for dreaming. In the meantime, take a look at H-VSK. It’s a great paper.