The morpheme-to-stress principle in Tohono O'odham

In this paper, I describe and analyse a no vel pattern of secondary stress in Tohono O'odham. Tohono O'odham (formerly known as Papago) assigns primar y stress to the first syllable in content words (Hale 1959; Saxton 1963; Hi ll and Zepeda 1992). Fieldwork by the author on Tohono O'odham shows that a word-final secondary stress is disallowed in monomorphemic words but is al lowed in polymorphemic words. This descriptive generalization holds regardl ess of the morphological composition or the derivational history of the wor d. This appears to be a novel stress pattern in the world's languages; no s imilar pattern appears in either Halle and Vergnaud (1987) or Hayes (1995), two important typological works on metrical systems. Optimality theory (Mc Carthy and Prince 1993; Prince and Smolensky 1993) ranks constraints in a s ingle hierarchy that evaluates both derived and underived words without a s erial derivation. O'odham secondary stress is accounted for in this way by proposing the morpheme-to-stress principle, a constraint requiring that eac h morpheme be stressed This is true, as long as rhythmic considerations aga inst clashes and lapses are respected. The morpheme-to-stress principle pro vides an optimality-theoretic account of this interesting metrical asymmetr y between derived and underived words in Tohono O'odham and offers an accou nt of other types of morphological stress systems.