LANGUAGE AND GENETICS – MUTANTS OF THE MIND

The “great mutant hunt”

We have argued that principles of universal grammar (i.e., of syntax, morphology, semantics, and phonology) have, with respect to the nervous system, a status much like that of Mendelian laws of classical genetics (Jenkins, 1979).That is, they are an abstract characterization of physical mechanisms which, in this case, reflect genetically specified neural structures.

Moreover, we argued that it made no more (or less) sense to ask whether what we then called “Chomsky's laws” were “psychologically real” than it did to ask whether “Mendel's laws” were “physiologically real.” If you were convinced by the evidence from the argument from poverty of the stimulus, or by other nonlinguistic evidence, that UG represented the genetic component or initial state of the language faculty, then it made sense to talk about the genes involved in the specification of the initial state. And one could ask the usual things that get asked about genes – what chromosomes are they on? Do they act in a dominant, recessive, polygenic, or other fashion? What do they do – are they structural or regulatory genes? And so on.

Objections were raised that Mendel's laws were either outmoded or else, if they still were operative at all, they didn't have much to do with UG:

A BRIEF CHRONOLOGY

Chomsky has posed what we consider to be the central questions for the study of language and biology (biolinguistics):

1. What constitutes knowledge of language?

2. How is this knowledge acquired?

3. How is this knowledge put to use?

4. What are the relevant brain mechanisms?

5. How does this knowledge evolve (in the species)?

Chomsky asks “how can we integrate answers to these questions within the existing natural sciences, perhaps by modifying them?” (Chomsky, 1991a:6). This more general question is part of what he has referred to as the unification problem, a topic to which we return below (Chomsky, 1994a:37,80).

The discussion of the questions (1)–(5) above within the tradition of generative grammar began in the early 1950s: “At least in a rudimentary form, these questions were beginning to be the topic of lively discussion in the early 1950s, primarily among a few graduate students. In Cambridge, I would mention particularly Eric Lenneberg and Morris Halle, and also Yehoshua Bar-Hillel” (Chomsky, 1991a:6).

The period between the mid-1950s and the present is sometimes referred to as the “cognitive revolution.” However, Chomsky has observed that contemporary work might be more properly viewed as a “renewal” of the “classical concerns” of the seventeenth and eighteenth centuries (Chomsky, 1997a). This earlier period of the study of mind, which includes as a central element the Cartesian theory of body and mind, might then be called the “first cognitive revolution” (Chomsky, 1994a:35). There are, in addition, many antecedents to modern-day studies of language and mind, both before and after this period.

The last forty years have witnessed what has been called the “second cognitive revolution” (see Introduction). A central focus in the study of mind (the “cognitive sciences”) is the study of language and its biological bases. Work on the biology of language, or biolinguistics, is directed at answering some traditional questions; viz., (1) What constitutes knowledge of language?, (2) How does knowledge of language develop in the individual?, and (3) How did knowledge of language evolve in the species?

There has been an explosion of knowledge about the first two questions from studies of languages and dialects that now number in the thousands. A small sampling includes: Basque, Bulgarian, Chinese, English, Dutch, Finnish, Flemish, French, German, Greek, Hindi, Hungarian, Icelandic, Irish, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Romanian, Russian, Spanish, Swedish, Turkish, Warlpiri, and Welsh. Evidence bearing on the answers to these questions is now available from numerous areas; e.g., syntax, semantics, morphology, phonology, articulatory and acoustic phonetics, language acquisition, language change, specific language impairment, language perception, sign-language, neurology of language, language-isolated children, creole language, split-brain studies, linguistic savants, and electrical activity of the brain, among others. The past year marks the thirtieth anniversary of Eric Lenneberg's Biological Foundations of Language, which surveyed the work in many of these areas and therefore provides a useful benchmark for the significant progress that has been made in recent years.

Although the three central problem areas for biolinguistics listed above have been investigated in parallel, most progress has been made in the first two areas: language and development of language.

THE FIVE FUNDAMENTAL QUESTIONS OF BIOLINGUISTICS

As already noted, since the earliest days of generative grammar five questions have been the focus of intensive research (see p. 1). Chomsky has often referred to question (1) as “Plato's problem,” question (2) as “Humboldt's problem,” and problem (3) “Descartes' problem,” to give some indication of the rich tradition, at times forgotten, of these classic questions (Chomsky, 1991a). In addition, Descartes' problem may be a special case of the problem of explaining how it is that the human science forming capacity sometimes yields a “partial convergence” with “our ideas and the truth about the world” (Chomsky, 1988a:158).

As Chomsky has noted, the answer to question (1), What constitutes knowledge of language? is of central importance to the study of the biology of language. This is because, to answer each of the questions (2)–(5), we have to have some idea of what the system of “knowledge” is. For example, to answer intelligently question (2), How is this knowledge acquired?, we need to know something about what knowledge the adult learner has acquired. If the computations of linguistic theory are properties of the language faculty, as will be argued, then these properties have to be accounted for somehow in a theory of language acquisition.

The same point can be made, with regard to physical mechanisms; i.e., question (4), What are the relevant brain mechanisms? To study mechanisms, you need to understand something about the computational properties of the system realized. As Chomsky says:

INTRODUCTION

We now come to question (5) (from p. 1), “How did knowledge of language evolve?” Throughout contemporary work on biolinguistics, there has been great interest in questions of evolution of human language. To answer this question we need to come to understand two things: (1) how human language is designed; and (2) how these design features evolved in the brain of our species. The study of language design has been part of the subject of the earlier part of this book, where we have discussed the questions of “what constitutes knowledge of language?” and “how is this knowledge acquired?”

The study of properties of language design goes back to the earliest days of generative linguistics; e.g., the functional explanation for grammatical transformations based on certain assumptions about short- and long-term memory (Miller and Chomsky, 1963) and the functional motivation for syntactic output filters (Chomsky and Lasnik, 1977).With the emergence of more restrictive models of language in recent years as a result of work on the problems of structure (of language) and development, it has now become possible (tentatively) to take up the consideration of the question of language design. For example, the “minimalist program” focuses explicitly on questions of optimality of language design (Chomsky, 1995b, Chomsky, 1997b). Keep in mind that we are assuming that any research program that is investigating the evolution of language, is interested in language design in this sense and hence has a “minimalist program,” even if it may be called something else. Hence our discussion in this chapter applies to the full spectrum of linguistic theories that have been proposed to characterize knowledge of language.

ACQUISITION

Principles-and-parameters model

Chomsky has proposed a “principles-and-parameters” model of language acquisition, which represents the first steps towards an account of the genetic basis of grammar (Chomsky, 1981, 1986, 1988a, 1993). The principles refer to conditions specified by the linguist's theory of universal grammar and are assumed to be part of man's biological endowment, a Bauplan for human language. The parameters are variables left open in the statement of the principles which account for the diversity found in human languages. The goal of the biolinguist interested in question (2) (p. 1), How is knowledge of language acquired?, is to come up with the formulation of genetic principles of UG narrowly enough constrained to account for the child's ability to learn structural properties of grammar of great subtlety from impoverished linguistic data, and at the same time, find parameters which can account for the manifest variation among, say, Germanic or Romance languages, or between these and non-Indo-European languages. As Chomsky remarks

In this book we have investigated aspects of the “five fundamental problems of biolinguistics”:

1. What constitutes knowledge of language?

2. How is this knowledge acquired?

3. How is this knowledge put to use?

4. What are the relevant brain mechanisms?

5. How does this knowledge evolve (in the species)?

As we have seen these comprise the classical questions asked about any biological system: (1) structure of the system, its function, and its use, (2) its development, and (3) its evolution. Our system of interest is language, so the areas pertinent to biolinguistics are (1) language, (2) development of language, and (3) evolution of language.

We have asked how the answers to these questions might be at least partially unified with each other and integrated into the natural sciences. We have argued that the evidence points toward a picture of unification in which there are a variety of cognitive systems, including language, each having its own specific properties and mechanisms. The available evidence appears to argue against the idea of a homogeneous and general purpose cognitive system designed to learn language, American history, and basket-weaving, or, as some would argue, even pigeon behavior.

We have also argued that the evidence for biolinguistics should include any and all relevant evidence. This is dictated by the constraint that scientific theories typically are radically underdetermined by evidence so we seek evidence wherever it is available. So, for example, in order to choose between particular formulations of a theory of English syntax, we can, and typically do, consider evidence from Japanese, Mohawk, Turkish, or any of the numerous other languages that have been investigated over the last forty years from the biolinguistic perspective.

Chomsky has commented as follows on the futility of attempting “the study of everything”:

The physicist David Ruelle, one of the founders of the field of nonlinear dynamics and chaos theory, writes in a similar vein: “Typically, if you are a physicist, you will not try to understand everything at the same time. Rather, you will look at different pieces of reality one by one. You will idealize a given piece of reality, and try to describe it by a mathematical theory” (Ruelle, 1991:11).

In biolinguistics, one such “piece of reality” that one might seek to describe is the relations and interpretations that hold between full phrases like fones and “silent subjects,” as in this example described by Chomsky: