A certain type of soundlaw that frequently seems to occur across the Uralic languages is the prothesis of a labial semivowel before “medium-strong” labial vowels. Two clear examples are Samic and Finnic, where this has occurred before the long vowel ⁽*⁾/oː/, but not short ⁽*⁾/o/, nor ⁽*⁾/u/ of any length. In Samic this comes up particularly frequently, due to the unconditional raising of previous *a to *ō. Thus e.g. PU *ëppə “father-in-law” → West Uralic *appə → pre-S *ōppë → proto-S *vōppë → Southern Sami voehpe, Northern Sami vuohppa, Skolt Sami vuõpp. (Contrast Finnish appi, Hungarian ipa, etc.) Or for an example from Finnic: PU *uwa “flow” → eLPF *oo → LPF *voo → Estonian voo, Finnish vuo. The effect, I suspect, is in these cases related to the diphthongization of *oo to *uo, which has independently occurred in both Samic and most of Northern Finnic.
This phenomenon also turns up in Permic, though with some interesting quirks. Three broad features set this case apart as remarkable among the Uralic languages:
- The appended consonant is *w, remaining distinct from PU *w → Proto-Permic *v. In Komi and several Udmurt dialects, the distinction has been lost with this secondary *w also spirantizing to /v/; but a genuine distinction between /w/ and /v/ turns up in some other dialects of Udmurt, alone of all Uralic languages (and, indeed, most other languages of western, central and northern Eurasia).
- The change occurs not only word-initially, but also following the consonant *k. This change seems to represent a major departure from the nearly pan-Uralic syllable structure template, which allows only a single onset consonant.
- Not all instances of the change occur in the vicinity of labial vowels, leaving the phonetical motivation of the change slightly unclear.
#1 and #2 are related features, I suspect. Tackling the 2nd of these first, the reconstruction of a lone initial consonant cluster *kw- in Proto-Permic seems in fact sufficiently odd to be untenable… this should probably be instead analyzed as a labiovelar monophoneme *kʷ! Its development back to /k/ in Komi might make better sense from this starting point too. Moreover an analysis as /kʷ/ should possibly be applied to Udmurt as well. Although my raw data sources on the language seem to incidate simply kw, one argument in favor of analyzing /kʷ/ is that w remains here even in the dialects where bare word-initial *w has been merged into /v/. The existence of a Permic *kʷ would also have a nice parallel with the existence of *kʷ in Mansi to the east.
Once the introduction of a labiovelar stop is understood as an areal feature, the same turns out to be applicable to the labiovelar glide. Permic originally seems to have been a “frontier” language with respect to the spirantization of original *w to *v: the subfamily is flanked by Mari and Mansi, both of which have to this day yet to shift their /w/ to /v/. Hence the appearence of secondary *w rather than *v can be explained as areal interference. It could even be speculated if the rendering of original *w as *v indicates Permic having originally occupied a more western location among the early Uralic dialect chain (not necessary perhaps, since the once-southern neighbor Hungarian also shows /v/)?
This explanation of the first two oddities, though, seems to only deepen the mystery of the third. A particularly clear example of *w before illabial vowels is Udm. *war ~ Komi /ver/ “slave”. Other similar instances are findable as well; this is however complicated by the fact that Udmurt seems to retain its labiovelars only before the open vowel /a/. But there is evidence that previously these occurred also before other vowels. Consider the following three words:
- Udm. /ɨm/ ~ standard Komi /vom/ ~ Komi-Permyak /ɤm/ “mouth”
- Udm. /ɨn/ ~ std. Komi /von/ ~ KP /ɤn/ “drape”
- Udm. /ɤsk-/ ~ std. Komi /vos-/ ~ KP /ɤs-/ “to vomit”
I would suggest that *wëëm, *wëën and *wësk- should be reconstructed here (modulo interpretations of the Proto-Permic vowel system), with *w lost in Udmurt and Komi-Permyak, but retained as /v/ in standard Komi. Moreover, these cases also suggest a soundlaw Proto-Komi *ë → Standard Komi /o/ after labiovelars (but not PP *v: cf. e.g. /vɤj-/ “to sink”, /vɤl/ “horse”, /vɤr/ “woods”, /vɤź/ “wigeon”), which allows bringing in several less direct cases before /k/:
- Udm. /kɨz/ ~ std. Komi /koz/ ~ KP /kɤz/ “spruce”; ← PP *kʷëëz?
- Udm. /kɤl-/ ~ std. Komi /kol-/ ~ KP /kɤv-/ “to spend a night”; ← PP *kʷël-?
- Udm. /kɤs/ ~ std. Komi /kos/ ~ KP /kɤs/ “dry”; ← PP *kʷës?
- Udm. /kɤt/ “belly” ~ std. Komi /kot/ “peritoneum” ~ KP /kɤt-a/ “pregnant (of cow)”; ← PP *kʷët?
- std. Komi /kod/ ~ KP /kɤd/ “who”; ← proto-Komi *kʷëd?
The Udmurt doublet /kɤj/ “fat” ~ /kʷajɨ-/ “to become fat” also adds some support for a loss of labialization before central vowels.
The mystery still isn’t particularly deep, though. Rewinding all these words backwards toward Proto-Uralic turns up mainly *o: *orja “slave”, *oŋə “mouth”, *owd₁əm(ə) “drape”, *oksɜ- “to vomit”, *kowsə “spruce”, *koksɜ “dry”, *koktɜ “uterus, belly”… The main exception is the interrogative pronoun, which seems to go back to *ku-. “To spend a night” has cognates only in Ugric and appears to be compatible with both *kola- and *kala-. It is also *o that can be reconstructed in the best-attested cases where Udmurt /kʷa-/ occurs:
- /kʷa/ “house” ← *kota
- /kʷal-d-/ “to split” ← *kolɜ “cleft”
- /kʷaś-/ “to dry” ← *kośkɜ-
- /kʷaśi/ “wild duck” ← *kośkɜ? (~ Khanty *kaas, Selkup *kʷëćə)
- /kʷar/ “leaf” ← *korwa? (~ Samic-Finnic *korva “ear”)
Hence it would appear that what originally happened here was very similar process as in Samic and Finnic: *o was broken to *wo (or labialized a preceding *k), and only later did the vowel diverge to various other reflexes.
Oddly though, cases of *wa- seem to instead mainly go back to original *a-ə:
- *wa “year” ← *ëd₁ə
- *waĺ- “to spread out, to cover” ← *ad₂ə “bed”
- *wadź “early” ← *anśə? (~ Mari *ažnə; also *onśə might be reconstructible)
- *wadźer “tusk” ← *anśər(ɜ)
Should an early labialization to *o be reconstructed here? It’s worth noting that PU *a, *o and *ë have very similar reflexes in Permic — all three seem to have PP *u as their main unconditional reflex, for starters.
Other questions remain as well.
- Can any Permic-Mansi loanwords be identified where *w or *kʷ would occur? If this is to be an areal feature, such cases could be suspected to exist.
- How shall cases where *k does not labialize before original *o be explained? Examples include at least *kočka → *kuč “eagle”, *kod₂ka → *kuĺ “spirit”, *kopa → *ku “skin”, *kośɜ “long” → *kuź, *kojə “male” → *koom “man”. Postulating any original distinction such as *k versus *q doesn’t seem to be supportable.
- Udmurt /a/ after labiovelars corresponds to Komi /o/. After a non-labializable onset, in words of this type (← PU *o-a and *a-ə) we however find PP *u = /u/ in both: this includes both the immediately previous examples, and many others, e.g. *tolwa → *tul “wedge”, *worka- → *wurɨ- “to sew”, *ńalə- → *ńul- “to lick”, *śarwə → *śur “horn”. Presumably *o was retained after labiovelars, and was furthermore lowered to /a/ in Udmurt. But the correspondence U. /a/ ~ K. /o/ (let’s denote it as PP *å for the moment) also sporadically turns up in some other words: e.g. *låjɨ- “to knead”, *måď “riddle” (← *mojə- “to remember”?), *pårś “pig” (← *porćas). What’s up with these?
- Could labiovelars have once occurred also before other Permic vowels yet, only to have been later lost? This is not obvious in any way, if they can be mostly traced back to original *o. But this would provide an interesting new mechanism for perhaps explaining some aberrant vowel correspondences.
In particular, Udmurt /ɨ/ frequently corresponds “irregularly” to Komi /u/ — and this looks rather analogous to the /ɤ/ ~ /o/ and /ɨ/ ~ /o/ correspondences brought up above. Several cases with original *ku- seem to turn up here: e.g. PU *kupsa- “to extinguish” → U. /kɨsɨ-/ ~ K. /kus-/ (= PP *kʷɨsɨ-??); PU *kuńa- “to blink” → U. /kɨń-/ ~ K. /kuń-/ (= PP *kʷɨń-??). But there are also cases of the normally expected *ku- → /kɨ-/ in Komi, e.g. *kud₁a- “to plait” → /kɨ(j)-/; and cases of this exception correspondence to be found after other consonants, e.g. PU *salka- “to stand” → U. /sɨl-/ ~ K. /sulal-/.
Perhaps some investigation into the Proto-Permic vocabulary not found elsewhere in Uralic could clarify these matters. I’ve yet to read Sándor Csúcs’ 2005 monograph Die Rekonstruktion der permischen Grundsprache; it should be interesting to see if he arrives at any conclusions alike to mine here.
 I seem to have somehow acquired a habit of denoting Proto-Samic long vowels by macrons (*ō), yet by geminated vowels (*oo) in other contexts. Originally this was motivated by the fact that “long” vowels in Proto-Samic seem to have been neutral rather than marked (e.g. in loanwords Finnic and Scandinavian *a is substituted by *ā). However, for full consistency I probably should extend this notation, at minimum, also to Khanty, where a similar situation applies; and indeed, its “long” vs. “short” vowels are actually full vs. overshort. Yet I continue to write *uu *üü *ää *a and not *ū *ǖ *ǟ *ă etc. for the language… this time largely out of disdain for stacked diacritics. I hope this isn’t making too much of a mess out of the followability of my writing.
 Curiously, Livonian retains this root as bisyllabic: õvā. It follows that the stage *oo → *voo needs to be considered Late Proto-Finnic, later than the splitting-off of Livonian and South Estonian during the Middle Proto-Finnic phase.
 A similar but weaker situation occurs in Selkup however, where following the fortition of inherited *w- to *kʷ-, a new epenthetic *w- has developed in a number of cases. For an actual distinction between /v-/ and /w-/, we need to look quite far though; examples of this occur in some Germanic languages (English, Middle High German), some Sinitic varieties such as Sichuanese, as well as some varieties of Chukotkan.
 The other main exception is Mordvinic, where retraction of stress from the 1st syllable has in certain cases (but predominantly in newer loanwords) led to its syncope.
 A singular counterexample that may actually be in support for this analysis is the numeral “6”, /kvať/. I suppose /v/ in here does not derive from older *kw/*kʷ, but instead from some kind of a syllable contraction, from something like earlier *kuať. An original trisyllabic shape such as #kuwətə is also suggested by the long vowel in Finnic *kuuci.
 Some descriptions of Mari and Mansi appear to posit /β/, but I’d guess this is not intended to stand for IPA [β], and is rather simply a case of the confusing UPA notation where fricatives and approximants are not distinguished, and “β” is moreover used as a broad transcription for [w].
 Incidentally, the fact that original *w is not lost in Permic in any position (*wülä → *vɨl “upper”, *wud₂ə → *vɨĺ “new”, *wosa → *vuz “ware”) independently suggests that *w → *v occurred very early on in the subfamily.
 Though the fact that this yields Hungarian hál-, Khanty *kaal- versus hal, *kuul from *kala “fish” may point to original *kola- being preferrable.