ASCENT OF INTELLIGENCE
Gesture and Language : Mind and Body
The acquisition of language was the turning-point for the evolutionary separation of humans from apes. From this flowed the ascent of human intelligence with the ratcheting up of human mental and cultural advance as a result of interaction between individual variations in brain structure and development and continually advancing complexity of the social, technological and cultural environment (a manifestation of the Baldwin effect).
Both body and brain were involved in the acquisition and advance of language, phylogenetically and ontogenetically. The relation between mind-state and body-state was manifested not only in the patterning of emotion (the James/Lange theory) but also in the selection of words (articulatory programs) to match patterns of perception, both of external objects and also innate attitudinal patterns, "mental" structures, which went to form both language syntax and motor syntax (cf. Karl Lashley, Kant).
The key aspect of the motor theory of language is that words, speech and language are the outcome of an exaptation of the motor control system, that is, a direct relation between aspects of the motor cortical system and the characteristic features of lexicon and syntax.
"Words are the natural evolutionary product of the functioning of the brain. The forms of individual words are not arbitrary but directly derived from and related to the meaning of the words."
"Speech is the result of an evolutionary exaptation: the establishment in humans of a direct connection between the cortical motor control system and the articulatory apparatus"
"In the evolution of language, shapes or objects seen, sounds heard, and actions perceived or performed, generated neural motor programs which, on transfer to the vocal apparatus, produced words structurally correlated with the perceived shapes, objects, sounds and actions."
"The motor program generating the word, an articulatory gesture, also generates an equivalent bodily gesture. Gesture mediates between word-structure and word-meaning. In the case of a different word in a different language for the same meaning, a similar final gesture is generated by a different intermediate trajectory associated with different speech-sound elements going to form the different word."
"Children are able to acquire words effortlessly, that is to link a word to an object or action, because, when the motor control system has sufficiently matured, the neural motor program generated by the perception of the particular object or action is matched instantaneously with the equivalent motor program generated on hearing the word which, in the particular language community, is structurally derived from the perceived object or action."s
Progress in neuroscience, and particularly recent experimental research using fmri and other techniques, has provided material support for the motor basis of language. Motor equivalence has been the central process in the origin and functioning of language and the acquisition of words. The sound [the word] is not "a directly imitative sign but indicates a quality which the sign and the object have in common. . . . sounds which partly independently and partly in comparison with others produce an impression which to the ear is similar to that which the object makes upon the mind." [Humboldt]
BRAIN SIZE AND THE ASCENT OF INTELLIGENCE
The inescapable fact is that brains, and particularly human brains, have much increased in size in the course of evolution. The increase in size must have brought survival benefits and for humans it surely means that, however intelligence is measured, greater brain size has moved in step with greater intelligence - though at the individual level the correlation is not exact. BUT … all the day-to-day routines of bodily existence require very little neural mass. Ants, bees, mice, birds, dinosaurs, manage, or managed, very well, with small, or extremely small, brains. Why and how did humans come to acquire a brain-mass much greater than is needed for routine bodily functions ? From home habilis to modern homo sapiens the brain grew from an average 750 cc. to 1350-400 cc. That the remarkable increase in human brain size (unmatched by any similar rate of increase in other animals) should have some relation to the equally remarkable (unmatched by other animals) evolutionary human acquisition : language, seems an obvious and plausible hypothesis. But the debate, confusion and uncertainty about the process by which humans invented, acquired or developed language, or languages, still rages, after 2500 years. The question goes with the unsettled question about the brain or social processes making possible another remarkable achievement, the untutored, extensive and rapid acquisition of language, complex syntaxes and massive lexicons, by children.
A NEW EVO-DEVO BALDWIN EFFECT: CELL DEATH IN DEVELOPMENT AND EVOLUTION
The accepted evolutionary account of the Baldwin effect has been that humans, and other animals, by changing their behaviour changed their environment and so created novel potentialities for natural selection which could operate in succeeding generations, making it possible for culture to modify evolution. With the recent growth of the new discipline Evo-Devo concerned with the relation between developmental and evolutionary processes, a new application or understanding of the Baldwin effect in relation to development of the brain becomes possible. In the development of the brain, many more neurons are produced than are ultimately needed to create the mature brain. The neurons are thinned out by programmed cell death; the initial supply of neurons (twice as many as eventually survive) are in competition to establish appropriate connections. Those which do not get the necessary access to a source of NGF (nerve growth factor) die. Through cell death each individual brain is sculpted to match the environment in which the brain develops. It is via cell death that the relation between brain-size and culture, including language, can be understood. A key point in the operation of this process in the developing brain is individual brain variation. Each brain is unique in many ways, including its size and the number of neurons which have to find appropriate connections to survive. Natural selection can come into play on differences in brain structure derived from the culture. Increased brain size means the availability of more neurons (and more neuronal inter-connections) available to match the extending experience of the individual- and so increase the selective advantage of the individual in a changing culture.
Language in the group will account for an ever-larger segment of total cultural input to the brain and will also act as a powerful instrument in shaping the social system. A ratchet effect is established which goes to promote a persisting increase in brain-size (and skull-size co-ordinated by allometry with brain-size) until the skull-size hits the anatomical constraint of birth-canal size. The brain keeps on growing in complexity to accommodate continuing language and other cultural changes. The major new language input to the brain is through a rapidly expanding lexicon. The growing lexicon, on the motor theory of language, requires that each word creates a articulatory motor program. The influx of novel words involves an increasing demand for neurons and neuronal connections
However, before the Baldwin Evo-Devo process can begin to operate to increase brain-size, there must already be language and language-related culture. There must already be words. The central question remains: WHY and HOW could speech and language have got going for humans at all? Why humans and not dogs or apes? Some identified cortical changes could have made speech possible for humans but for the Baldwin Evo-Devo effect to operate there had to be words. Where does any individual word come from? Herder said that it was totally impossible that words should be arbitrary. Rizzolatti and Arbib have argued that the discovery of mirror neurons linking responsive motor programming in the brain of an observer with observed motor patterning of action of other individuals, could have been the basis for the evolution of language.
Some things can be indicated by gestures, a tree, the sky, a direction, up or down, come and go, high and low. Gesture can be used to point to things, to indicate hearing, eating or drinking, etc. but for many things manual gesture is inadequate: colours - white black red -, sounds, different animals; what would be a manual gesture for a horse, a fish, a rose, a cabbage? Mirror neurons may have made imitation possible, including imitation of gesture, but what matters is stored imitation (requiring commitment of neurons and interconnecting fibres) in the form of a link between word and imitated act, sound or shape so that there can be ready access to the word and what it refers to. Words are anchored in the motor patterning and are expressible as bodily and articulatory gesture. Was each gesture as arbitrary as traditional linguistics says that each word is? Clearly not. Gesture is patterned by the action seen, the shape of what is seen, the sound heard for a vocal gesture.
The process by which words were formed was the inverse of the process by which gestures and sounds can be generated from existing word-forms - a reverse application of motor equivalence. On seeing some one hitting something, the action patterning was by motor equivalence converted into articulatory patterning to produce a speech-sound structure, a word, directly related to the action patterning seen. Similarly on hearing an animal sound, the typical sound of a cat or a lion, the sound-patterning is transduced by motor equivalence to form a word whose structure is derived from the sound heard.