Introduction

The linguistic capacity of human beings is a biological endowment. The normal child placed in a typical speech community will acquire the language of that community in a consistent fashion. While the specific language a child acquires is a function of the linguistic environment, how any child acquires any language is, in fundamental respects, the same. Acquisition can be impaired either by deprivation of linguistic experience or by various forms of anomaly in the central nervous system. Observation of the everyday experience of human language acquisition provides, then, compelling evidence of a biological foundation for language. Linguistic capacity is, in fact, not unlike a host of other biological capacities: the organism encounters experience with a physical system poised to engage with that experience and develop in consequence of it. It is therefore of consequence to explore the biological foundations of language if we are to gain a clear understanding of the structure of human linguistic capacity.

It is impossible to study the functional structure of any biological system in the absence of some concept of the function being subserved. Little follows directly for the analysis of particular behavioral systems from simply looking at neurons, collections of neurons, their physiological properties, or their chemistry. Thus, consideration of the biological foundations of language requires that we have at the outset some behavioral conception of human linguistic capacity. Led by the extensive work of Chomsky, over the last quarter century, considerable research on the theory of grammar has been dedicated to providing a formal account of the endowment which a child brings to the task of language acquisition (Chomsky 1965, 1985).