In this paper wc present an approach to modeling emergent syllable systems using simulated evolution of a "vocabulary" of "words." The model is aimed at testing the general hypothesis that language-universal sound patterns emerge from selection pressures exerted on the system by the perceptual and articuatory constraints of language users. The model is able to distinguish between hypotheses about how specific, biologically-motivated constraints affect the sound structure of language. For example, it is shown that mandibular oscillation provides a strong constraint on the sequential organization of phonemes into words. Future work will explore the potential of other constraints that, with mandibular oscillation, will be sufficient to describe the emergence of syllable systems.