NATO/ASI Cortona 1988
[Adapted from Language Origin: A Multidisciplinary Approach, 105-119 ed. by Jan Wind et al. Dordrecht: Kluwer.]
1. THE THEORY OUTLINED
2. SUPPLEMENT AND EXTENSION
This paper presents the motor theory of language developed over the last few years in earlier international conferences including particularly meetings of the Language Origins Society. The theory is applied both to the origin of language and to language as a current function. Part I gives a general outline and Part II relates the theory to recent work in linguistics, brain research and artificial intelligence.
There have been other motor theories of human function. In particular, there was J.B. Watson's motor theory of thought and there was also the much-discussed motor theory of speech perception. The theory presented here is a more general one than either of these and it takes into account progress in research into the organisation of action at the neural level. The theory is that language originated as a transfer from or translation of the elements and system of combination of elements of the neural motor system, with the expression of motor programs which originally developed for the co-ordination of vertebrate movement being redirected from the skeletal muscles to the muscles of the mouth, throat, chest etc. with the side-product that this expression of the motor programs was accompanied by the sound produced by modulated streams of air which we recognise as speech-sound. The theory is thus one of a change in the connectability of the neural system, the opening up of new channels for the external expression of motor programs. "In the brain, new functions, phylogenetically and ontogenetically, had to be grafted on to old ones in whatever manner proved to be feasible and consistent with the normal processes of evolution. At every stage, evolution had to improvise with the anatomical structures and inherent plasticities that happened to be available"(Sommerhoff, 1974 p.13). In so far as it is assumed that the redirection of the motor programs, the opening up of new channels, took place many hundreds of thousands of years ago (and could in any case never have been directly examined) the evidence for the motor theory cannot be direct but must be probabilistic or circumstantial.
So much for a summary statement of the theory. But what do we mean by language or by the origin of language? Language is taken to be the capacity of one individual to alter, through structured sound emission, the mental organisation of another individual. As regards the origin of language, we should not look for a distinct, datable origin any more than we would look for a distinct, datable origin for the eye. Language is more than speech just as perception is more than the structure and functioning of the eye. In both cases we have also to be concerned with the neural organisation underlying the functions of speech and visual perception.
The implication of the proposition that language was constructed on the basis of a previously existing complex system, the neural motor system, is that the programs and procedures which evolved for the construction and execution of simple and sequential motor movements formed the basis of the programs and procedures going to form language. At every level of language, from the elementary speech sounds, through the word-forms on to the syntactic rules and structures, language was isomorphic with the neural systems which already existed for the control of movement.
A second main idea is that language developed by a process of mosaic evolution. This meant the fitting together of a whole array of elements, anatomical, neural and behavioural. Many of the elements necessary for mosaic evolution of the language capacity can be found in the anatomical and behavioural repertoires of other animals, and particularly of birds.The conclusion drawn is that if birds and other animals have, individually, behavioural elements required for the evolution of human language-capacity, then they must have the neural structures required to produce these behaviours, and in particular the neural motor programs which are required to support them.(Brown, 1974; Nottebohm, 1976; Phillips and Peck, 1975; Sutherland, 1964; Thorpe, 1967; Welker, 1976). That other animals have these elements separately also shows that a mechanism for the development or acquisition of the elements, in evolutionary terms, must exist.
Whether or not the individual elements going to form the language capacity each separately had survival-value -the development of language might have been an example of evolution by accumulation of neutral mutations (Kimura, 1983) - language as such clearly had a major survival value, not so much for the individual as for the group which possessed language. Language is essentially and unavoidably a group possession, a group behavioural attribute. As such, it serves to increase a group's competitiveness and to promote evolution by way of group-selection. Any group of animals with an effective means of communication within the group e.g. ants or bees as well as humans, are in a position to react to events external to the group with a group-reaction, and so also to be subject to evolution by way of group-selection rather than individual selection. Hence the evolution of diverse castes of ants, bees and termites. In the case of humans, "it seems necessary to invoke a selective process acting between group and group, with the groups persisting as semi-permanent units, giving time for the better-integrated ones to prosper and supplant those that are less vigorous" applying Wynne Edwards' comment (1986 p.1) to the usefulness of language to competing human groups. Eibl-Eibesfeldt refers in this connection to Bigelow's view that the origin of man's rapid evolution lies in inter-group warfare... "man's tendency to cluster into small groups (pseudospeciation) and to compete aggressively with others certainly provided a motive force for this evolutionary development. In a tragic way we are indebted to aggression for the rapid development of our intellect" (Eibl-Eibesfeldt, 1975 p.509)- one of the most powerful forces in pseudospeciation and in aggressive intergroup struggle must have been the development of language.
Mosaic elements required for language notably include imitation and the categorical perception of speech sound. We take the power of imitation in ourselves, in birds such as the parrot or mynah, and in animals such as the chimpanzee, very much for granted but imitation, of speech or other sound or bodily movement, is in reality a most surprising ability. It involves a remarkable and complex linking of perception and motor organisation. The ability of some birds, mynah birds par excellence (Thorpe, 1967), to imitate human speech sounds precisely shows that the production of the sounds of speech is not dependent on any narrowly specified articulatory apparatus, and suggests that one should not expect to trace the development of speech simply in terms of gross anatomical features (Nottebohm, 1976; Wind, 1976). A second important mosaic element for language is the capacity to discriminate categorically between human speech sounds in a way similar to that found in adult speech perception - an ability found in a variety of animals, notably in chinchillas (Burdick and Miller, 1975; Kuhl and Miller, 1975), monkeys - and indeed in extremely young human infants.(Morse, 1976; Kuhl, 1987; Kuhl and Meltzoff, 1982)
A crucial feature in each of these two important elements of the mosaic, and in other behavioural requirements for language, is the intimate involvement of the motor control system and their dependence on cross-modal processes. The development of the language capacity has resulted from the progressive establishment of new cross-modal(Ettlinger, 1967; Ettlinger and Blakemore, 1967) or trans-functional neural linkages, cerebral re-organisation in the sense that the interconnectedness of different brain regions concerned with what are usually considered distinct functions, has substantially increased. Evolution of language brought together in the human brain homologues or analogues of neural structures spread across a range of animals, and established neural connections between them.
Such an extensive relation between language and the motor system is what one might reasonably expect, given the central role of the motor system in all behaviour and the essentially motor character of speech production, as the outcome of movements of the articulatory apparatus.(Fowler et al., 1980; Kertesz and Hooper, 1982; Kimura, 1973, 1976; McNeill, 1981; Ojemann and Mateer, 1979; Penfield and Roberts, 1959) The existence of a relation with the motor system has long been recognised, for example in the speech perception theory associated with the Haskins Laboratories and Alvin Liberman.(Liberman et al., 1967; Liberman and Mattingly, 1985) In view of the prominence of the motor system in the mosaic elements which might have gone to form the language-capacity, it seems a necessary next step to undertake a systematic examination of what is known about the relation between each aspect of language and corresponding features of motor activity and the motor system. In addition, because of the intimate relation between the use and content of language on the one hand and perception on the other, the examination should extend to the relation between the motor system and perception in all its forms.(Turvey, 1977) The motor system is seen as the indispensable mediator between different modalities, and particularly between language and perception.
This leads on to the idea that the neural motor system may be formed from a limited array of components. In an earlier paper (at Cracow in 1986) I suggested that new light could be thrown on this by using the hypothesis that the motor system, prior to the development of language, was built up from a limited number of primitive elements - units of motor action - which could be formed into more extended motor programs.This would make it possible to look for a direct correspondence between the primitive motor elements and the fundamental elements of spoken language, the phonemic system, and at the same time would allow one to derive the processes of word-formation and syntactic rules for constructing word-sequences from the neural rules governing the union of motor elements into simple and more complex actions. Motor activity and speech activity would thus be shown to have similar and in fact systematically related structures and rules. Language would be one type, though an exceptionally special and valuable type, of skilled action.
It followed from this that one must deal with the system of motor control and the nature of motor programming.(Bernstein, 1967; Brooks, 1986; Evarts et al., 1985; Hoyle, 1983; Kelso & Clark, 1982; Schmidt, 1982) The effect of linking the system of motor control for bodily movement to the neural control of the mouth and other anatomical elements which became part of the articulatory system, was that new channels were opened up for the external expression of motor programs The motor system already has externally expressive functions, most notably in facial expression. If language is derived from the motor system, one preliminary but important point is that language cannot be in any way arbitrary. This applies not only to the sound-elements of language, the phonemic system, but also to the words formed from these elements and to the ordering rules which constitute the syntactic structure of language. There is strong experimental evidence that the phonemic system is not arbitrary (Kuhl, 1987; Lindblom, 1983; Macneilage, 1983), suggestive evidence that word-forms are not arbitrary but are expressive or appropriate to their meaning (Allott, 1973; Brown, 1958; Koehler, 1964) and there is also considerable evidence for a fundamental relation between the syntax of language and physiological syntax, the syntaxes of action and perception.(Kertesz and Hooper, 1982; Kimura, 1973; Lashley, 1951; Lieberman, 1984; McNeill, 1981; Ojemann & Mateer, 1979) There is no evidence which compels one to accept that phonemes, words or syntax are arbitrary. This conclusion, that language is not arbitrary, in phonology, syntax or lexicon, runs counter to accepted linguistic orthodoxy. It provokes the immediate challenge how then can one explain the extent of diversity between languages, particularly in lexicon. The topic is important enough to justify full-length treatment and has been dealt with in my paper for the 1989 LOS Meeting at the University of Texas, Austin, under the title 'Reconciling the Motor Theory and the Diversity of Languages'
An unexpected result of this approach was the perception that the motor theory is not only a theory of language origin and development but also a theory of current language function. The proposition that language is completely analogous to skilled motor action opens up a new direction of enquiry, the applicability to language of the extensive and surprisingly successful research into the neural bases of action, of motor control. Recent research (Bizzi, 1983; Desmedt, 1985; Evarts et al., 1985; Hollerbach, 1985; Kelso & Clark, 1982; McKay, 1985; Marsden et al., 1985; Robertson & Pearson, 1985; Selverston, 1985; Taub et al., 1973) strongly supports the concept of motor programs and motor subprograms as real and not merely formal or theoretical bases for the organisation of action. An important task in brain theory is to isolate the substructures of motor behaviour, to identify what might be called the repertoire of detached motor programs and sub-programs, and how these are used by central organising programs. The elementary motor programs may well be innate, part of standard human (and even vertebrate) neural structure. They may form part of fixed action programs or be formed by a central motor program into novel action-sequences. Motor programs are not necessarily dependent for their functioning upon incoming sensory information. They may run without any afferent information, as research on invertebrates has shown. The similarities in motor programming between a wide range of animals, birds, insects, suggest that common general principles have evolved in neural control of movement. In humans, in the light of evidence bearing directly on the relation between arm and head movements and speech, one may reasonably look for parallel pre-programming of the comparable speech musculature movements.
It is possible to examine the implications of the proposed relation between motor programming and speech programming at each level, the phonemic, the lexical and the syntactic. For phonemes, this leads to the idea of an invariant program for each phoneme, or 'auditory targetting' (Lindblom, 1983; Macneilage, 1983), a motor-alphabet underlying speech, related in some way to the elementary motor-patterns underlying other forms of action.The surprising phenomenon of categorical speech perception has a direct bearing on this. A range of animals and very young infants have displayed, in repeated experiments, the ability to categorise speech-sounds, natural or synthesised, in ways which match the category boundaries in adult speech; very young infants have been shown to discriminate categorically speech-sounds not found in their mother language.(Kuhl, 1987) On the motor theory presented in this paper, the explanation for this must be that the categorisation of speech-sounds is derived from organisation prior to language, and specifically from the categorisation of motor programs used in constructing and executing all forms of bodily action. What the rhesus monkey, or the chinchilla, share with the young human infant is very similar skeletal and muscular organisation, with very similar processes for the neural control of movement generally.The specificity of the phoneme is the accidental result of the application of the different elementary motor subprograms to the muscles which went to the form the articulatory system.The hierarchical structure of the motor system is built on the basis of a limited set of motor elements, which are combined in an unlimited number of ways (motor-words), just as phonemes can form an unlimited number of spoken words.
Words, as neural structures, can be formed from the co-activation of the motor subprograms for phonemes which are then melded or shingled together to form a distinct neural program for the whole word. Words are a read-out of neural structures in much the same way as actions or facial expressions. Experimental approaches with the creation of artificial words have suggested that there can be a lawful relation between speech-sounds and auditory or visual percepts. Research into sound-symbolism strongly suggests that there is an isomorphism at the motor level between speech and the contents of perception. The object seen produces a motor-pattern which is readily transferable as a motor-program to the articulatory system and so becomes the associated word for the thing. The process involved is similar to that by which we transfer into our own neural organisation the motor-program underlying the facial expression of others, smiling, yawning or frowning, and so may reproduce in our own expression the expression which we perceive in another.
The motor programs which go to form the neuromuscular sequences underlying words are derived from the integration of the neural structures underlying perception in all its forms (visual, auditory, tactile etc.) and motor organisation. The assumption that the last stage of the perceptual process and the first stage of the motor process are one and the same is attractive because it solves the problem of imitation. The subparts of the perception and action systems are thought of as pieces of a jigsaw puzzle that are made to fit each other.(Turvey, 1977)
If phonemes and word-forms are derived ultimately from the motor system (if necessary modulated by the perceptual system) it seems inevitable that there must also be a close relation between the organisation of motor activity, motor syntax, and the organisation of language, speech syntax. If this is so, then beside speech-elements (phonemes), speech-element compounds (words) and speech sequences (syntax word-strings) on this theory one can now set a motor-alphabet (of elementary motor programs for bodily action), an array of motor-words (actions formed from motor-elements) and motor-sentences (formed from sequences of motor-words). Section B of Part II of this paper briefly discusses more detailed aspects of the relation between the motor theory and syntax.
As already indicated, the motor theory of the origin and development of language in this paper is also in substance a motor theory of the current functioning of language. A theory of this kind fits well with the current trend of research into neural motor control and the neural basis of perception. It also has points in common with what Pribram described as his central motor theory of the origins of human language, based on a close relation between the imaging of action, perception and speech(Pribram, 1971 p.369). It is built fairly directly on Karl Lashley's (1951) ideas on the underlying uniformity of the neural organisation of action and language, though it inverts his approach; where he started from the then current analysis of the hierarchical structure of language, the present approach takes motor programming as primary and derives the structure of language, as a motor phenomenon, from the necessary processes in the organisation of action, as demonstrated in research into neural control of behaviour patterns in a range of experimental animals. Curiously, this theory could be presented as a return, at a deeper level, to earlier ideas on the essentially motor basis of brain processes, though Watson of course had an over-simplified and incorrect view of the real complexities involved in motor organisation. Because the motor theory of the origin and development of language is at the same time a theory of the current functioning of language, it is also potentially a theory of the ontogenetic as well as phylogenetic development of language. It can be a useful instrument for illuminating and investigating both speech and motor organisation, at the neural level and in extended speech and action sequences.
Section 2.1 presents material drawn from a variety of specialist fields tending to support the importance of the relation between motor control and language. The growing consensus unfortunately still excludes linguists wedded to a generative or purely formal approaches to language function. Section 2.2 summarises an approach to the application of the motor theory to syntax (discussed more fully in a paper on syntactic iconicity presented at the 12th International Congress of Anthropological and Ethnological Sciences).
Over the last few years there has been a good deal of research and theoretical development which directly or indirectly supports the central idea of the motor theory, that language is founded on the pre-existing structures of the motor control system of the brain. The material comes from a number of directions, neurology, artificial intelligence and computer modelling of brain function, linguistics, language pathology.
In mainstream philosophy, Patricia Churchland (1986) has sought to bring home to philosophers the relevance and importance of progress in brain research. This leads her to recognise the importance of motor organisation: "If we think of motor control as a fundamental function for nervous systems, then increased sophistication in nervous systems is, in this broad sense, understandable as an increasingly sensitive means of controlling behavior on the basis of sensory information. As organisms compete for scarce resources, efficiency of motor control is at a premium; and nervous systems with more sophisticated motor control will have a selective advantage over those whose motor control is less efficient... To follow evolution's footsteps in discovering how basic principles of motor control are refined and upgraded to yield more complex systems is a productive strategy. Additionally, it may be a shift in focus that allows us a breakthrough in the attempt to understand the higher functions. If we can see how the complexity of behavior that we call cognition evolved from solutions to basic problems in sensorimotor control, this can provide the framework for determining the nature and dynamics of cognition... Put crudely brains are not in the business of pattern recognition for its own sake, and the nature of pattern recognition, as accomplished by brains, must be understood in the context of its role in how brains achieve motor control. Evolution being what it is, pattern recognition is there to subserve motor coordination. And what goes for pattern recognition in this regard goes also for learning and memory... if we ignore motor control as the context within which we try to understand pattern recognition, we run the risk of generating biologically irrelevant solutions."(p. 441, p. 473)
In the AI approach to language, Arbib and his collaborators have aimed at approaches which are plausible in terms of neurology. Most practitioners of cognitive science "believe that their ignorance of brain research is a virtue, and that human intelligence can be studied as symbol-manipulation without concern for its embodiment... [Arbib's latest book Arbib et al., 1987] offers a view of cognitive science that places linguistics in a common framework, offered by schema theory, with research in brain theory and the study of action and perception.. To provide a bridge to our analysis of perception, we now observe that there are important parallels between visual perception and speech understanding on the one hand, and between speech production and motor control on the other... While noting that language behavior is highly developed in humans, we stress that it is a system of communication and that it involves both action and perception. We see it as mediated by a brain that has evolved from other brains, and thus, as one of several goals, we seek to understand the brain mechanisms of language within a wider analysis of brain mechanisms subserving action and perception". Arbib suggests "that language did not arrive de novo but came by differentiation of, and building upon, pre-existing systems (such as the perceptual-motor systems..)".(pp. v, 5, 15, 68)
From linguistics, Jackendoff in a recent paper: "How can we talk about what we see?.. one of the most fundamental problems for a theory of natural language.. A point of connection must be found between the theory of language and the theory of vision".(Jackendoff, 1987 p.90) Slobin summing up an extremely extensive cross-linguistic survey of language acquisition concludes: "Detailed examination of the ways in which children acquire a variety of different types of languages leads to the inescapable conclusion that the structure of human language is highly adapted to the structure of human perception, thought and action - and that the capacity to construct a human language must, ultimately, be part of the genetic capacity of our species".(Slobin, 1985 p. 1244)
From clinical brain research (direct electrical stimulation of the exposed cortex as part of the treatment of epilepsy), Ojemann: "These observations also suggest the conclusion that a large portion of the brain related to language is fundamentally a part of the motor system. Other evidence for the concept has.. been presented by Kimura and her associates".(Ojemann, 1983 p. 195) Buckingham in commenting on Ojemann's important 1983 article: "The commonalities with language production and other motor functions lead to the ultimate claim that the linguistic system has been evolutionarily built upon the general motor capacities of the brain".(Buckingham, 1983 p. 209)
Studdert-Kennedy (referring to Ojemann's findings):"Taken together, these facts almost force the hypothesis that the primary specialisation of the left hemisphere is motoric rather than perceptual. Language would then be drawn to the left hemisphere because the left hemisphere already possessed the neural circuitry for control of the fingers, wrists and arms..- precisely the type of circuitry needed for control of the larynx, tongue, velum, lips and of the bilaterally innervated vocal apparatus".(Studdert-Kennedy, 1982 p. 333)
There has been a good deal of use of the concept of persisting motor programs that can be assembled into large structures or applied to different muscle-groupings. Apart from the general evolutionary and functional link between motor control and language, an important aspect of the theory is the idea that both motor programs and language are formed from elementary units, with units of motor action being directly related to units of speech-sound. In a recent paper, Soviet researchers suggest:"It is likely that the most complex motor acts, such as speech production, are based on the ability of the nervous system to combine different motor components. Comparison of central mechanisms for speech production and for limb movements is a special theme that is now very much under discussion." Discussing adaptability of innate motor patterns and motor control mechanisms: "Adaptability of movements is based on their discrete organisation.. it is common to find that movement trajectories are divisible into segments with various parameters (curvature, speed etc.) This segmentation may also indicate that movements are a combination of elementary dynamic components". Referring to multiple forms of motor-equivalent programs: "The motor programs considered.. remain unchanged in form during continuous regulation of the parameters involved".(Berkinblit, Feldman and Fukson, 1986 pp. 594-598) Similarly, Gracco and Abbs : "these results and discussion point to a dynamic hierarchical model of speech motor control utilising distributed motor control processes and interacting neural subsystems... This flexible hierarchical system allows for the operation of multiple, parallel, subtask actions.. Together these distributed sensorymotor systems appear to interact dynamically to produce the coordinated movements of human speech."(Gracco and Abbs, 1987 p. 191)
This section summarises some still tentative ideas on the more detailed relation of the motor theory of language to syntax (in the context of discussion of the iconicity of syntax). Iconicity is interpreted essentially as mapping or isomorphism from one structure to another, eg. from visual or action organisation to syntax. But there is no consensus about the concept of syntax. I take it to be the processes by which words are put together to convey meaning, not accepting the currently fashionable view that syntax is to be defined as the formulation of rules to generate acceptable, ie grammatically well-formed, sentences in any language. This undervalues the importance of meaning in language as contrasted with grammatical form.
There are three major components of any syntax (on the interpretation of syntax I am using). The first component comprises the principal word categories Noun and Verb to which should added the dependent categories of Adjective and Adverb; the second component comprises ordering and sub-ordering rules for word-strings; the third component consists of the closed class of function words (and function sub-words, functional morphemes). The syntax of a language results from the co-operation and interaction of the three major components.
What justification is there for choosing these three major components? Little needs to be said about the justification for selecting the principal word categories as a major component of syntax or for treating ordering (and sub-ordering) rules as a major component - there is general acceptance of these in all current discussion of syntax. More extended justification is needed for treating the class of function words as a distinct major component of syntax; evidence for the neurological, and operational reality of the closed class is drawn from clinical findings in aphasia, from brain stimulation experiments in the treatment of epilepsy and from the use of function words as a key component in AI natural language parsing programs.
Using this identification of the major components in syntax, the next step is to explore the significance of the motor theory in relation to each of the major components, that is, the detailed possible relation between motor control (both for bodily action and for vision) and the principal open word-categories, word-order and the class of function words.
For the open categories (Nouns and Verbs), the existence of these classes is seen as deriving both from the actual manner of operation of vision - the pattern of movements of the eye (saccades, fixations, tremor and accommodation). These aspects of the motor functioning of the eye already show a clear distinction between visual operations relating to static elements in the visual scene and visual operations involving perception of movement and change in the visual scene. Once the broad parallel between Nouns and Verbs and static and movement aspects of visual perception is established, the two dependent classes follow (Adjectives and Adverbs) as modifiers of the leading categories.
For the second major component of syntax (ordering and sub-ordering of words in the utterance) the relation postulated is between the word-string as a serial process and the action of visual perception also as a serial process governed by the pattern of scanning over the visual scene (including aspects of salience and emphasis). At the same time, ordering of the word-string is linked to the serial ordering of bodily action more generally, where salience may be equated with variations in relative force of different segments of a complex action.
The relation of the motor theory to the third major component of syntax, the closed class of function words, is in some ways the most important, and at the same time requires the breaking of the most new ground. The function word component of syntax is where the most considerable differences are observed between languages in terms of how far they depend on separate function words, as largely in English, and how far they depend on function sub-words (inflections, morphemes for forming eg. abstract word-classes etc).
To relate the class of function-words to the motor theory, the first step is to prepare a list of words considered to be function words. This cannot be based on any simple treatment of traditional parts of speech, prepositions, conjunctions etc. as function words. A function word or function subword is a speech-form which has no definable external reference and which acts in association with other function words to determine the role of non-function words in the word string or utterance (in English often to decide whether open-class words are acting as Nouns, Verbs or Adjectives and whether the non-function words are operating as Subject, Object, Complement etc).
If, as the theory proposes, the syntactic components are derived from the motor control system (either from the organisation of action or from the motor control organisation underlying perception), then the next stage is to consider how in detail the closed-class of function words and subwords have analogues in the motor control system or could be derived from aspects of motor programming required for what Gregory described as 'the grammar of vision' or from what a motor control researcher referred to as 'the grammar of action'.
Features of function words which can be compared with operational aspects of 'action grammar' or 'vision grammar' include, for example, timing, direction and relative position, salience, emphasis and force, hesitation, choice, change of direction, linkage and sequence.
Classification of function words using categories such as these is meant only as an indication of the lines along which study of the relation between motor programming and the class of function words might proceed. What it might lead to is a clearer idea of how the segments of motor programs might be fitted together, using our knowledge of syntax (in the sense proposed in this paper) to throw light on motor control just as much as using motor control and vision research to help us to tackle syntax in a new and biologically more relevant way.
This paper has covered a good deal of ground and in particular has dealt with material on motor control less familiar to readers concerned primarily with language. It is inevitable that a theory of language origin which relates the structures of language to the (previously evolved) vertebrate neural structures for movement should attempt to demonstrate a secure basis in current research into motor control. Neural motor control is a vast and active field of research; some attempt was made in earlier papers for LOS meetings, at Oxford in 1986 and at Vanderbilt in 1987, to draw together the relevant results and theories. The main points relevant for the motor theory are:
1. The central role in all behaviour of motor control. Language is an important segment of behaviour; it is itself action and is integrated with perception and bodily action.
2. Motor control makes use of modules, pre-wired motor programs. Thus there are elements (motor units) which can be put in correspondence with the sound-elements of language. There must also be neural rules for forming motor programs into action-sequences; these served as the basis for the syntactic rules by which words are assembled into utterances.
3. An important issue in motor control research is the operational links between perception and action. The motor theory of language origin proposes that the original structures of word-forms were derived from the neural processes linking perception and action.