Proto-Gäj language

Proto-Gäj (abbreviated PGäj; also called Proto-Gajic or Proto-Arklobu) is the reconstructed ancestor of the Nambāno and Arklobu languages, which together form the "Gäj" branch of the Arklobu-Qachkav languages.

Consonants
The voicing of earlier plain plosives *p *t *c *k (*kʷ) → *b *d *ɟ *g (*gʷ) is assumed to have already taken place in Proto-Gäj due to the reflection of PAQ *cʰ *c by Nambāno /s z/, which would be an unusual change without first going through the voicing step, as well as some additional evidence from Arklobu. The aspirated plosives *pʰ *tʰ *cʰ *kʰ (*kʷʰ) may well have retained their aspiration, but the only contrastive feature which can be reconstructed for Proto-Gäj is the voicedness, so their reflexes are transcribed *p *t *c *k (*kʷ).

Vowels
The vowel length contrast was present in the oldest form of Proto-Gäj, the ancestor of all Gäj languages, but was lost in the Northern Gäj languages which comprise the majority of the Gäj family.

Phonological Stages from Proto-Arklobu-Qachkav to Proto-Northern Gäj
The following sound changes are reconstructed to have occurred, roughly in the order presented, in the development of Proto-Gäj from its ancestor Proto-Arklobu-Qachkav. In each example given, the start (PAQ) and end point (PGäj) for each word is shown, with relevant intermediate steps underlined.

Proto-Northern Gäj (PNGäj)
Proto-Gäj then further developed into the later dialect Proto-Northern Gäj, the common ancestor of the core Gäj group consisting of Arklobu and Nambāno. Characteristic phonological changes include i-mutation which developed grammatical ablaut in transitive verb conjugation, and a shift in the qualities of the long vowels resulting in a loss of contrastive vowel length. The sound changes from Proto-Gäj (PGäj) to Proto-Northern Gäj (PNGäj) are shown below.

Transitive Verbs
Transitive verbs had three conjugation paradigms; perfective, imperfective and irrealis; each with a different form of the verb stem. Proto-Northern Gäj is more readily reconstructible than Proto-Gäj, so the morphology presented here is mostly PNGäj in order to better elucidate the precise structure of the conjugation paradigms.

The three forms of the stem are distinguished as follows:
 * Perfective stem:
 * -∅ on consonant-final roots, *-x on vowel-final roots (note realisation as *-xʷ before the 2sg, 2pl and 3pl suffixes *-ɒkʷu, *-uːp > *-(w)op and *-uːk > *-(w)ok respectively)
 * Imperfective stem:
 * Mutation of final obstruents:
 * p *t *c *k *kʷ > *f *x *ç *x *xʷ
 * b *d *ɟ *g *gʷ > *p *t *c *k *kʷ
 * (in Northern Gäj only) Fronting ablaut of final vowel in stem:
 * {*-i-, *-ɨ-, *-u-} > *-i-
 * {*-e-, *-ə-, *-o-} > *-e-
 * {*-æ-, *-ɒ-} > *-æ-
 * Irrealis stem:
 * -ən on consonant-final roots, *-n on vowel-final roots.

Some examples of vowel-final and consonant-final transitive verb stems, featuring Northern Gäj ablaut, are shown below.

The suffixes are shown below, with the later Proto-Northern Gäj forms also shown where there are differences.

The imperfective suffixes appear to be descended from PAQ infinitive series {*-kʰi, *-kiː, *-kʰiːkʰ, *ʡiː} with an unknown suffix *-r and irregular infixing on the second person suffix *-ciː⟨r⟩k. This unusual development represents the only finite verb forms developed from the PAQ infinitives present in the Arklobu-Qachkav family.

The irrealis suffixes are the reflexes of the reconstructed suffixes of the PAQ conditional series, reflecting only the singular person forms and dropping the plurals. { *-(ə)ntʰx₂əʡ, *-(ə)ncʰʊːʡ, *-(ə)ntx₂əʡʊ , *-(ə)ntx₂əyʊ, *-(ə)nqtx₂ə , *-(ə)nqtx₃əʡ}.