Summary

The Yam languages are a primary language family spoken in southern New Guinea across an area spanning around 180km west to east across both the Indonesian province of Papua and Papua New Guinea.

The Yam languages are morphologically remarkable for their complex verbal inflection characterized by a tendency to distribute inflectional exponence across multiple sites on the verb. Under this pattern of distributed exponence, segmental formatives, that is, affixes, are identifiable but assigning any coherent semantics to these elements is often difficult and instead the inflectional meanings can only be determined once multiple formatives have been combined. Despite their complex inflectional morphology, Yam languages display comparatively impoverished word formation or derivational morphology.

Nominal inflection is characterized by moderately large case inventories, the largest displaying 16 cases. Nouns are occasionally marked for number although this is typically restricted to certain case values. Verbal paradigms are much larger than nominal paradigms. Verbs mark agreement with up to two arguments in person, number, and natural gender. Verbs also mark complex tense, aspect, and mood values; in all languages this involves at least two aspect values, multiple past tense values, and some level of grammatical mood marking. Verbs may also be marked for diathesis, direction, and/or pluractionality.

The overall morphological pattern is that of fusional or inflectional languages. Nominal inflection is rather straightforward with nominals taking case suffixes or clitics with little to no inflectional classes. The true complexity lies in the organization of the verbal inflectional system, about which, despite individual variation across the family, a number of architectural generalizations can be made. The family displays a fairly uniform verbal inflectional template and all languages make a distinction between prefixing and ambifixing verbs. Prefixing verbs show agreement via a prefix only while ambifixing verbs via agreement with a suffix, for monovalent clauses, or with both a prefix and a suffix for bivalent verbs. These agreement affixes are also involved in the distributed exponence of tense, aspect, and mood.