THE FRAME CONTENT THEORY OF EVOLUTION OF SPEECH PRODUCTION (CORRECTEDVERSION OF 126BQ)/

The species-specific organizational property of speech is a continual mouth. open-close alternation, the two phases of which are subject to continual articulatory modulation. The cycle constitutes the syllable, and the open and closed phases are segments - vowels and consonants, respectively. The fact that segmental serial ordering errors in normal adults obey syllable structure constraints suggests that syllabic ''f rames'' and segmental ''content'' elements are separately controlled i n the speech production process. The frames may derive from cycles of mandibular oscillation present in humans from babbling onset, which ar e responsible for the open-close alternation. These communication-rela ted frames perhaps first evolved when the ingestion-related cyclicitie s of mandibular oscillation (associated with mastication [chewing] suc king and licking) took on communicative significance as lipsmacks, ton guesmacks, and teeth chatters - displays that are prominent in many no nhuman primates. The new role of Broca's area and its surround in huma n vocal communication may have derived from its evolutionary history a s the main cortical center for the control of ingestive processes. The frame and content components of speech may have subsequently evolved separate realizations within two general purpose primate motor control systems: (1) a motivation-related medial ''intrinsic'' system, includ ing anterior cingulate cortex and the supplementary motor area, for se lf-generated behavior, formerly responsible for ancestral vocalization control and now also responsible for frames, and (2) a lateral ''extr insic'' system, including Broca's area and surround, and Wernicke's ar ea, specialized for response to external input (and therefore the emer gent vocal learning capacity) and more responsible for content.