sounds to construct conventionalized vocalizations makes the distinction among vocalizations a categorical/digital
matter rather than a graded one.
Recall Lieberman's (1984) observation that, as late as the Neanderthals (however they are related to us), the shape of
the vocal tract did not allow the multitude of easily perceptible distinctions among speech sounds found in modern
language (this point is disputed by Aiello 1998). Lieberman, however, points out that an open vocabulary is still
possible with a less highlydifferentiated phonologicalsystem. For example, with a repertoire of ten distinctphonemes,
one could still construct thousands of words of reasonable length; after all the modern language Hawaiian makes do
with only thirteen phonemes. The evolution of the vocal tract—and of the brain machinery that operates it—can be
seen as driven by the adaptivity of a larger vocabulary, made possible in part by more rapid articulation and enhanced
comprehensibility.
An intermediate stage in evolving a phoneme-based vocabulary might have been based on the syllable rather than the
phoneme as the generativeunit. The syllable is basicallya unit of articulatory gesture, and, as we saw in Chapter 5, the
rhythmic organizationof language (stress and timing)revolves around the syllable rather than the individual phoneme.
Its basic organization is a move from some relatively closed position of the mouth, through a relatively sonorous
segment (usually a vowel but occasionally a“syllabic consonant,”as in thefinal syllable ofsyllable), to relative closure
again (either the close of the syllable or the beginning of the next). MacNeilage (1998) proposes that this basic for mis
an adaptation fro mthe mouth's basic close–open–close cycle used for chewing.
The syllable demonstrably plays an important role in speech perception and production. Levelt and Wheeldon (1994)
offerpsycholinguisticevidencethat therepertoireof most frequentlyused syllables (generallynumbering around a few
hundred) is stored in what they call a“syllabary”; among other things the syllabary includes a repertoire of motor
scripts that aid in rapid articulation.
Clara Levelt (1994) suggests that children around one year of age organize their phonetic articulation in terms of
syllables that are not entirely decomposed into independent phonemes. The earliest words tend to have a uniform
place of articulation: the mouth opens and shuts but tongue and lip position are held constant. Thus child prefers
words such as /tin/, in which the tongue tip is near the teeth throughout, or /pom/, where the lips form the major
vocal tract constriction throughout. Then the child begins to vary the place of articulation within the syllable,
producing things like /pin/, wheretheclosure starts at thelipsand endswiththetongue ontheteeth.Itis at thispoint
that we can begin to speak of the child having a real differentiation into phonemes.