Calvin, William H. and Derek Bickerton
Lingua ex Machina:
Reconciling Darwin and Chomsky With the Human Brain
Cambridge, MA: MIT Press, 2000

Editorial from MIT's CogNet (below)
Abstract and manuscript for comments (external).
Other books and articles by Calvin (external).

Publisher's endorsements

In a lively back-and-forth across disciplines, Calvin and Bickerton wrestle language to the mat in a way no single author could. Why did language evolve, and what kind of existing blueprints in the brain did it enlist? Rather than depicting language as a stand-alone instinct, the authors see it as the culmination of many different developments, some of which started long before our species appeared on the planet, such as tit-for-tat cooperation. The result is a delightful introduction to the language origins debate Chomsky's agnosticism on the matter notwithstanding by two veteran debaters.
-- Frans de Waal, Emory University, author of Good Natured and Chimpanzee Politics.

How does language arise, in the species and in the individual, from other capacities? How did the right neurobiology evolve? How, in children, do linguistic systems form? Why do they take so long? In Lingua ex machina, Calvin and Bickerton, in a refreshing spirit of courage and wonder, advance directly and insightfully into the amazing details of the hardest questions.
-- Mark Turner, University of Maryland, and author of The Literary Mind: The Origins of Thought and Language.

"Lingua ex Machina is the result of a fascinating and unlikely collaboration between two highly original thinkers--a linguist and a theoretical neurophysiologist--who have spent their careers considering the evolution of the human mind from these very different perspectives. The result is something halfway between a synthesis and a dialogue, that leads the reader on a challenging ride through some of the most interesting and controversial topics in the science of mind.
-- Terrence W. Deacon.

A machine for language? Surely not, say the people who associate  machines with stolid reliability - language, after all, is the basis for  metaphor, up there near the heights of creativity. Machines aren't  creative (and if they try, we get them repaired). Surely yes, say the  neurophysiologists, busy studying the language specializations of the  human brain and trying to identify their antecedents. What else could it  possibly be?

Linguists like Noam Chomsky talk to about machinelike 'modules' in the  brain for syntax, that language is more of an instinct (a complex  behavior triggered by simple environmental stimuli) than it is an  acquired skill like riding a bike or playing the piano. That's because  many potential systems for syntax are never used in any human language,  making you wonder what's common to the ones actually used (a common  neural substrate, in all likelihood - and that suggests that genes might   have something to do with it). But structured language seems to present  the same evolutionary problems as forelimbs for flight: you need a lot of specializations to fly even a little bit. So how are you going to get  them, if evolution has no foresight and the intermediate stages don't  have intermediate payoffs? Many argue that the same  long-time-until-useful objection applies to the structured aspects of  language. The wonderful Darwinian scheme for species self-improvement  cannot, they say, explain our most valued human capability, the one that  sets us so far above the apes, language itself.

How, then, do we reconcile the facts arrayed around 'Darwin' and  'Chomsky' with the obvious, namely that the human brain has the capacity  for structured language? That children routinely discover its principles  in the first few years of life, inferring them from the sound chaos that  surrounds them? Fortunately one can avoid invoking miracles by simply  taking a less cartoonlike view of evolutionary mechanisms. Charles  Darwin himself was careful to emphasize that natural selection need not  be for the same thing, all along the evolutionary path to a given  function: the usefulness of a structure could be initially for one  function, and then the structure might become useful for some very  different function. Darwin's example was that a swim bladder might have  been converted into a primitive lung, for venturing out onto land.  Forelimb feathers might have been under selection for thermoregulation  and, when there were enough for gliding, the selection might have  shifted to emphasize airfoil efficiency. Something paid for in one coin  might, when reaching some critical mass, become useful for a new  function, with further improvements paid for with a new coin. Foresight  might have accomplished this more quickly, but it really isn't required  for the result. 'Preadaptations' suffice.

But it has been difficult to identify nonlanguage predecessors of  structured language. Most books on language evolution seem to dissolve  into a series of vague generalities when it comes to deal with specific  issues, such as how language acquired its universal characteristics, or  what novel processes in the brain made language possible. The linguists  haven't known the relevant neurology or evolutionary theory, and the  brain researchers haven't known enough linguistics to realize what  features required a detailed explanation. And there is, in addition, the  requirement of continuity: How do your proposed mechanisms create an  easy series of improvements or conversions of function, stages that span  the whole distance, starting with chimpanzeelike utterances, working up  to words and protolanguage, and finally to the phrases and clauses that  enable you to say "I think I saw him leave to go home" with its nested  embedding?

We do it here with about two-and-a-half preadaptations, yielding both  argument structure and phrase structure or, if you prefer, the newer  minimalist grammar. The coin in which these improvements were purchased  was that of reciprocal altruism, the cognitive categories handy for  detecting cheaters, and of ballistic movement planning, handy for  toolmaking and hunting. And, of course, once structured sentences were  possible, natural selection could operate on improving it. Since  planning ahead and chains of inference are likely to use the same neural  mechanisms as syntax, their usefulness can also drive improvements in  syntax mechanisms. But the invention of such structured symbolism can be  a sidestep in evolution, one of Darwin's conversions of function in  anatomical continuity.

The mental categories needed for reciprocal altruism, a well-established  phenomenon in many primate species, show a strong resemblance to those  needed for understanding a structured sentence. The detection of  freeloaders, important in any primate society, became crucial with the  emergence of dyads that cemented their alliances by mutual grooming,  food-sharing, and so forth. If such stable arrangements were not to  collapse into an anarchy of freeloaders, it became necessary to detect  cheaters. But this in turn required a cheater detection method that  would keep a rough score of transactions via a template for events which  contained slots for Action, Agent, Theme (or Patient) and other abstract  roles such as Beneficiary.

The categories and event structure required for cheater detection are  precisely the thematic roles and argument structure that later form the  core of universal syntax. It is envisaged that this cheater detection  mechanism anticipated the earliest forms of language by millions of  years, and that it co-existed for perhaps two million years with a  primitive protolanguage until a crucial threshold in brain development  was crossed that allowed the two quite independent developments to mesh  smoothly with one another. Once the core structures and properties of  syntax (including recursivity) had thus been laid down, novel selective  pressures would have come into operation and a series of 'Baldwin  effects' would have quickly formed and fixed other universal features,  such as the use of grammatical morphemes for government and case  assignment, and an algorithm for assigning reference to unspoken  arguments (the equivalent of Chomskian 'chains' and the 'Empty Category  Principle').

Another preadaptation for structured sentences can be seen in the  movement planning needed for hammering and throwing. First came two  developments that were related to an increase in the efficiency of aimed  throwing, essential if hominids were to survive through temperate-zone  winters when food-sources other than meat were rare or nonexistent. One  of these was an increase in the number of neurons required to reduce  timing 'jitter' as improved range and accuracy called for an ever  narrower launch window, a factor that helped to drive brain expansion.  The other was an ever more detailed planning of the complex sequences of  segmented movements - upper body, shoulder, arm, wrist, etc. - that  precision hammering and aimed throwing require. Each rotation is  embedded in the ones higher up, as when wrist rotation has to be planned  on the basis of an lower arm that is itself accelerating, and elbow  planning is itself embedded in upper arm movement, and so forth.

These developments in cognition and movement planning, apparently quite  unrelated to any 'higher process,' produced unforeseeable consequences  for all of higher intellectual functions. The process of 'training up'  abstract and intricately embedded movement sequence commands would serve  as an important preadaptation for the nested embedding of phrases and  clauses, once other developments had made it possible to produce long  and complex sentences.

But perhaps the most crucial event was the achievement of coherence in  the transmission of long-distance corticocortical messages, the  equivalent of the fiber optic bundles used in endoscopes for viewing  ulcers. The anatomy is incoherent (axons do not consistently remain  neighbors over long distances) but physiology can temporarily correct  for it. This arose in part as a result of ballistic movement planning.  It made possible the large cell assemblies necessary not merely to  establish consistent codes for nominal and verbal concepts, but to  handle the composite codes that resulted as word-codes were merged to  form phrase-codes and phrase-codes were merged to form codes for clauses  - all to be transmitted, coherently and without any learning  prerequisite, to the motor organs of speech that would execute the  resultant sentence. The increase in size of the cell-assemblies that  could be recruited for each of these superposed, coded messages likely  drove an increase in the number of fibers in the arcuate fasciculus, one  of the main pathways of the brain (second only to the corpus callosum),  which links the prefrontal and temporal lobes most crucially involved in  language production, and this increase in turn helped make it possible  to achieve the coherence threshold required for accurate transmission at  the high speeds required by speech.

While all these developments were, of their nature, gradual and  incremental, they were not of a type that, individually, would have  brought about much improvement in language; indeed, they would not  likely have taken place if language had driven them rather than  throwing. Structured messages in the brain that are not fully coherent  are not partially coherent: they are completely incoherent, and with  anything less than a coherent message, the brain could not produce a  long sentence. Thus the final crossing of the coherence threshold would  have allowed language to pass in a single step from a structureless  protolanguage to something that would have been recognizable as a modern  human language, although it might at first have lacked some of the  streamlining features that Baldwinian evolution would later fill in.

For many decades, we have faced a dilemma. On the one hand we have had  the thesis of Chomskian nativism, with its unimpeachable evidence. On  the other we have had the antithesis of Darwinian evolution, with its  unimpeachable evidence. The whole problem, not just with language  evolution but with the understanding of all higher intellectual  function, has been that these two bodies of unimpeachable evidence  seemed to point in contrary directions, and countless millions of words  of print have been devoted to warfare between them - a warfare doomed to  futility, since the work on each side contained profound truths which  partisans of the other felt obliged to denigrate, deny or simply ignore.  Lingua ex machina shows that the apparent opposition between these  bodies of thought is illusory, and presents a synthesis showing how a  universal, innate language faculty could have been produced without  violating any of the basic principles of evolutionary theory. As such,  it presents a constructive message that should gain the attention of all  who concern themselves with our place in nature.

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William Calvin is a theoretical neurophysiologist at the University of  Washington in Seattle. His web pages start at www.WilliamCalvin.com.  Derek Bickerton is an emeritus professor of linguistics at the  University of Hawai'i in Honolulu.