Chapter 8 summarizes the ramifications of the Laryngeal Articular Model for the phonetic description of voice quality and investigates its place in phonetic theory. Predispositions for background voice qualities to underlie different vowel qualities are identified. It is argued that there is a parallel between the coarticulatory path that infants follow in their earliest speech development and elements in the process of phonetic sound change. The laryngeal articulator as an enabler of sound change is explored. Theories of ontogenetic speech development are reviewed (concepts of ‘speechlikeness,’ autogeneration, frame/content, cyclicity, reduplication, variegation) and reinterpreted to reflect the scope of laryngeal behaviour outlined in this volume. The discussion evaluates the implications of the revised view of laryngeal phonetic behaviour for the phylogeny of human speech. The physiology of the larynx is shown to permit a wider range of speech production than formerly assumed and to accommodate, on phonetic grounds, an earlier time period for the appearance of speech in human ancestors, as hypothesized in recent anthropological and genetic research.