Proto Chinese

[Otto Kretschmer]

Is it reconstructed to any significant degree? As far as I know, the earliest recnstructed stage is Old Chinese from approx 1000 BC. Are earlier stages of the language reconstructed at all?

[Nortaneous]

No. There's still no consensus on where Sinitic falls within Sino-Tibetan, so it's unclear what it should be compared with. Aside from Chinese-internal evidence, there are early Sinitic strata in Bai (which are probably not of much comparative use yet because Bai is highly eroded) and pre-MC sesquisyllabic loans in Mon-Khmer (which Baxter and Sagart have started taking into account in their OC reconstruction), but both of those probably postdate OC.

Speaking of OC being typologically Mon-Khmer, could the A/B palatalization have developed by some Adjarian's Law-like route from breathy vowels? Probably not - I don't know of any regional precedent for interaction between phonation and frontness (although there is regional precedent for interaction with height - e.g. Pacoh) - but the other proposals aren't great either.

[Nachtswalbe]

Why did the number of tones gradually reduce to 4 in Mandarin from Middle Chinese?

[zompist]

Why did the number of tones gradually reduce to 4 in Mandarin from Middle Chinese?

I don't think there's any way to say why, but the first thing to notice is that ru tone was spoiled by the loss of final stops, so its syllables were distributed to the other tones. So after that change, it was 6 tones down to 4. And that's just a merger of upper and lower registers in two of the MC tones.

Merger of MC tones is not uncommon in other dialects: e.g. Shanghai has 5, Hailu has 6, Xiamen has 6, Guangzhou has 7.

[Nachtswalbe]

Why did the number of tones gradually reduce to 4 in Mandarin from Middle Chinese?

I don't think there's any way to say why, but the first thing to notice is that ru tone was spoiled by the loss of final stops, so its syllables were distributed to the other tones. So after that change, it was 6 tones down to 4. And that's just a merger of upper and lower registers in two of the MC tones.

Merger of MC tones is not uncommon in other dialects: e.g. Shanghai has 5, Hailu has 6, Xiamen has 6, Guangzhou has 7.

Concurrent to this, I notice an increase in disyllabic and polysyllabic words due to a reduction in syllable complexity and the need to avoid similar-sounding words, and a movement towards agglutination along the grammatical clock