Proto-Namb language

Proto-Northern Gäj (abbreviated PNGäj) is the reconstructed ancestor of the Nambāno and Arklobu languages, which together form the Northern branch of the "Gäj" languages.

*ɸ and *θ
The fricatives *ɸ and *θ developed from Proto-Gäj *pʰ and *tʰ before stops (nasals and plosives). Although these consonants are reconstructible in PNGäj, their phonemic status is not clear, as the vast majority of them are present only in inflectional forms where a consonant-initial suffix was attached to a stem-final *pʰ or *tʰ. For example, Proto-Gäj *pʰɛ́pʰ-mi, *ǣ́tʰ-mi "leaf-ɢᴇɴ, snake-ɢᴇɴ" become Proto-Northern Gäj *pʰə́ɸ-mi, *éθ-mi. The difficulty in understanding whether these consonants are phonemic comes in certain inflectional suffixes which triggered fronting of the stem vowel but did not have an initial consonant, for example the PNGäj reflex of PGäj *pʰɛ́pʰ-īru "leaf-ᴇʀɢ" may have been either *pʰə́pʰ-yeru or *pʰə́ɸ-yeru, with phonemic /ɸ/. A more detailed examination is presented in the section on stem mutation below.

Semivowels
The semivowels *y and *w occurred only as medial consonants in onset clusters, having historically been fortified to *ɟ and *gʷ respectively in onset position and lost in medial and coda position, affecting the quality of the preceding vowel in the latter case. Semivowels were rare in Proto-Gäj but became more frequent in Proto-Northern Gäj due the vowel shift *ī *ū > *ye *wo.

Stem mutation
Both nouns and verbs exhibit mutation of the final vowel and consonant in the stem in certain inflectional forms, with every stem generally having two forms: basic and mutated.

Basic stem
The basic stem is used in the perfective conjugation and the absolutive, lative and oblique nominal cases. This is the unmarked form of the stem which may take any vowel and any final consonant. When vowel-initial suffixes are attached to the basic stem, *-x- is inserted between the stem and the suffix which may be realised as *-xʷ, for example on the second and third person perfective suffixes *-akʷʰu, *-ækʰi, *-wopʰ (< *-ūpʰ), and *-wokʰ (< *-ūkʰ).

Mutated stem
The mutated stem is used in the imperfective verb conjugation and the ergative, genitive and ablative nominal cases. If the final vowel of the stem is a back vowel *u *o *a, it undergoes ablaut, in which it is shifted to the corresponding front vowel of the same height: A stem-final obstruent is mutated generally according to the following rule:
 * *-u- > *-i-
 * *-o- > *-e-
 * *-a- > *-æ-


 * b *d *ɟ *g *gʷ > *p *t *c *k *kʷ

Stem-final plain plosives did not exist on verbs and nouns due to a sound change which voiced them in all circumstances in which they remained.
 * pʰ *tʰ *cʰ *kʰ *kʷʰ > *ɸ *θ *ç *x *xʷ

The two alternating stem forms developed through coincidences in inflectional morphology which caused multiple independent sound changes to frequently occur together, and the compound phonological variation which arose becoming recognised as a common pattern. For example, the first and second person imperfective suffixes *-cʰer (< *kʰīkʰ) and *-cʰerkʰ (< *kʰī⟨r⟩kʰ) blocked the voicing of a stem-final plain plosive which had become voiced in the perfective and irrealis conjugations, or triggered spirantisation of an aspirated plosive, and triggered ablaut of the previous vowel in the stem. In nominal inflection, the genitive suffixes *-mi (< *-m̥i) and *-mīŋ (< *-m̥īŋ̊) also triggered consonant mutation and ablaut, as did the ablative suffixes.

This pattern was then extended to forms which were affected by some sound changes but not others which had been associated with them. For example, the animative ergative suffix *-nus had a voiceless initial consonant in PAQ -n̥us which blocked voicing and allowed spirantisation, but did not trigger fronting of the stem vowel. By analogy with other mutated forms, the stem vowel is fronted in Proto-Gäj, for example PAQ *ā́q-n̥us > PGäj *ǣ́k-nus "hill-ᴇʀɢ" rather than the expected **ā́k-nus.

There are two inflectional forms which triggered the fronting of the stem vowel but not mutation of a stem-final consonant, resulting in a mixed form between the basic and mutated stems: the inanimate ergative noun suffix *-īru, which became *-(y)eru in Proto-Northern Gäj; and the third person imperfective verb suffix PGäj *-īr > PNGäj *-y(e)ru. For example PGäj *ā́g-/*ǣ́k- "hill" would be expected to have the form *ǣ́g-īru "hill-ᴇʀɢ" according to regular sound changes from PAQ *ā́q-īru. In fact, it appears that a similar analogical pattern was applied to always mutate the consonant of the mutated stem, even in an environment which would have voiced it, thus *ǣ́k-īru is reconstructed in Proto-Gäj.

A problem arises in the reconstruction of stems with final *pʰ and *tʰ in Proto-Northern Gäj, which according to the aspirated plosive mutation rule would yield *ɸ and *θ respectively in the mutated stem. Unlike the dorsal fricatives *ç *x *xʷ which pose no issue, the fricatives *ɸ and *θ were not otherwise phonemic and would have been made phonemic by applying the mutation with originally non-mutating suffixes. For example, PGäj *ǽtʰ-īr "plead-3.ɪᴍᴘꜰᴠ" would be expected to result in PNGäj *ǽtʰ-yer according to regular sound changes, but mutation by analogy with the first and second person imperfectives *ǽθ-cʰer and *ǽθ-cʰerkʰ may have produced *ǽθ-yer. This could have yielded *θ in a phonological environment where it would contrast with *tʰ, though no such contrasts are reconstructible. Nambāno is known to represent the result of such analogy, for example PGäj *ǽtʰ-cʰīr, *ǽtʰ-cʰīrkʰ, *ǽtʰ-īr are reflected by Pre-Nambāno *áh-cʰer, *áh-cʰerkʰ, *áh-er. The only other daughter branch of Proto-Northern Gäj, Arklobu, simply merges the aspirated plosives into fricatives in all positions, yielding a fricative from an ancestral aspirated plosive in both stem forms regardless of mutation, for example Pre-Arklobu *éθ-yer, *éθ-çerx, *éθ-er. Despite both branches reflecting fricatives in the 3.ɪᴍᴘꜰᴠ (*áh-er vs. *éθ-er), PNGäj may still have reflected *tʰ, since the analogical step may have taken place only in Pre-Nambāno later on, changing *átʰ-yer to *áh-yer by analogy with *áh-cʰer and *áh-cʰerkʰ. The phonemic status of *ɸ and *θ is therefore technically not reconstructible, though it may be reasonable to assume all these analogical processes took place around the same time, which would have yielded phonemic *ɸ and *θ in PNGäj. By convention and for simplicity, *ɸ and *θ are usually transcribed as separate consonants in Proto-Northern Gäj, including as mutated forms of *pʰ and *tʰ.