I’ve previously posted about the Proto-Uralic “dental spirants”, and on the problems concerning their reconstruction. These are however far from the only PU segments whose reconstruction involves unsolved difficulties.
The velar nasal *ŋ provides examples of some different types of problems. Thanks to direct retention in a good number of Uralic languages (most consistently in Samic, Mari, Khanty, and most parts of Samoyedic, but also in dialects of Erzya and Udmurt), there can be little doubt that a phonemic velar nasal occurred in Proto-Uralic. However, the historical development of the consonant is speckled with irregularities, and uncertainty on where it is and is not to the reconstructed.
A major part of the puzzle is the Ugric treatment. No single regular reflex can be identified in these languages. Instead the consonant appears to bifurcate, with no clear conditioning. One portion of words excretes a following homorganic plosive: *ŋ > *ŋk, further > Hungarian g. Clear examples include e.g. the word for ‘mouse’: PU *šiŋərə > H egér, Mansi *täŋkər, Khanty *ɬööŋkər; contrast Finnic *hiiri, Mordvinic *šeŋəŕ > šejər ~ ševər, Permic *šɨr, etc.
Another portion however fails to participate in this development. In Khanty, a plain nasal *ŋ remains in such words, while in Mansi and Hungarian, the initial reflex seems to have been a spirant *ɣ (which may later have vocalized). For these words, we might posit a distinct Proto-Ugric *ŋ. This split, although never explained, has been one of the traditional arguments for establishing a distinct Ugric group in the first place.
One front of attack that I think could help make some sense of the Ugric mess is to extend the scope of analysis to the other Uralic languages. I’ve conducted an initial survey on the matter, and one result appears to be that none of the > *ŋk words have secure Samoyedic reflexes. Which may sound uninteresting, but does have interesting consequences: as is the case for most of the other supposedly Ugric phonetic innovations (*s > *ɬ, *ś > *s, *k > *ɣ, etc.), there is here, too, no explicit reason to exclude Samoyedic! That is, *ŋk in these words might as well also be an older, East Uralic feature? At least one unclear comparison, PU *jäŋə ‘ice’ (> Ms *jääŋk, Kh *jööŋk id.) ~ PSmy *jåŋkå ‘hole in ice’ possibly even shows the exact same change (unless this is to be analyzed as a suffixed derivative: *jåŋ-kå < *jAŋə-kA). In all cases where PU *ŋ is reflected as PSmy *ŋ (e.g. *suŋə > *təŋə ‘summer’), the Ugric languages, too, point to “unbroken” *ŋ (here: Ms *tuj, Kh *ɬoŋ id.)
The Permic evidence offers some interesting views as well. More on this particular front of investigation later as the research develops, though — I’ve several new ideas, but the details remain in flux by this point. Ask me again in a couple of years if I have not found the time to return to this subject before then. :)
[Edit 2016-03-13: See now my post Proto-Uralic *ŋx? for one possibility.]
A look closer inward, that is investigating the vocabulary particular to Ugric, reveals further complications as well. The relatively clear split between *ŋ and *ŋk that is present in the oldest Uralic material dissipates here into chaos.  In many examples Hungarian points to *ŋ while Ob-Ugric to *ŋk, or vice versa; sometimes Mansi and Khanty disagree with each other, too. Multiple explanations would be possible in this situation… My own working hypothesis is that “Ugric” is merely a western areal subset of the East Uralic branch, and that much of the vocabulary shared between the three branches is to be analyzed as later diffusions, not as common inheritance. Perhaps the change *ŋ > *ŋk is to be dated as an areal innovation as well — but this remains to be seen.
There is also at least one correspondence where positing original *ŋ seems simply mistaken. This is a decent-sized set of words where Hungarian g corresponds to Ob-Ugric *ɣ. To run a small case study, examples include at least:
- H ág ~ Ms *taɣ ~ Kh *ɬaɣïï ‘branch’
- H fog- ~ Ms *puw- ‘to grasp’
- H nyereg ~ Ms *naɣr ~ East Kh *nööɣər ‘saddle’
- H szaguld- ‘to rush’ ~ Ms *šoom- ~ Kh *saaɣəL- ‘to gallop’, Kh *suuɣəm ‘jump’
- H tegez ~ Ms *täwt ~ Kh *tüüɣət ‘quiver’
First off, note that none of these reflexes shows any direct evidence for an original nasal. Usually at least Khanty retains *ŋ as is, and yet here we get *ɣ instead. There also seem to be no examples of the “next-most regular” correspondence: H g ~ Ms *ɣ ~ Kh *ŋ.
I suspect that these words are to be explained, not from a Proto-Ugric *ŋ that was expanded to *ŋk only in Hungarian, but as relatively recent parallel loans, and that the loan originals featured the voiced stop *g. In Hungarian the option to carry this over directly was available; while in Ob-Ugric, where phonemic voiced stops seem to have remained alien ever since Proto-Uralic, the closest substitute was *ɣ.
Numerous other phonetic irregularities also appear here, some of which could also have resulted from parallel loaning: most prominently Mansi *š in ‘to gallop’; Hungarian ny and Core Mansi *a (but Southern Mansi näwrää!) in ‘saddle’; Khanty *üü in ‘quiver’.
Note moreover how the meanings ‘gallop’, ‘saddle’ and ‘quiver’ are all specialized cultural terminology, and hence these are likely to be loanwords related to the Ugric peoples’ adoption of a steppe nomad lifestyle.
In some cases, loanwords of this layer might have reached Permic, too. As a particularly clear case, Hungarian reg ‘morning’ has been considered related to Permic *rög ‘warm’ — yet, Ob-Ugric #reɣ ‘warm’ seems equally relevant. Equating all three is however not possible if we insist on common inheritance: on one hand, the change *ŋ > *ŋk clearly never extended into Permic, and on the other hand, there is no evidence for a reduction *ŋk > *ɣ in Ob-Ugric. Loaning from Hungarian to Permic could be posited, but if so, why not loaning from “Language(s) G” to Permic directly? The latter scenario seems slightly preferrable in light of another example: Permic *mög ‘riverbend’ ~ Ob-Ugric #mVɣəɬ ‘around, circle’, for which no Hungarian cognates are known. 
Even further evidence for a non-nasal origin for this correpondence can be teased, I believe, out of its occurrence in an apparent consonant cluster:
- H buzog (buzg-) ‘to seethe’ ~ Ms *pëësɣ- ~ Kh *paasəɣ- ‘to drip’
If we were to be consistent with the earlier view, and to reconstruct Proto-Ugric *pësŋ-, this would be the sole example of an obstruent + nasal cluster in the inherited Ugric lexicon!  Additionally, the g/ɣ issue is not the only suspicious feature — no, literally every sound correspondence between Hungarian and Ob-Ugric (z ~ *s, u~ *ëë, b ~ *p) is irregular here. The first of these seems especially telling: if an original *g is assumed, it would be plausible to also assume that the first member of the consonant cluster was not *s, but the likewise voiced *z. This then can be assumed to have been substituted by voiceless *s in Ob-Ugric, but by *z in Hungarian… which would bring us to come one step closer to eliminating the sometimes supposed “sporadic” voicing of medial *s in Hungarian. 
Theories involving unattested substrate languages offer, of course, an easy way to explain whatever one wishes. Does my new explanation actually offer any advantage over the traditional view of leaving the origin of “areal” words open? Certainly, much of this hangs in the air so far, but it should be possible to seek further evidence. Perhaps known Turkic / Mongolic / Iranian loanwords can confirm or deny my supposed substitution pattern *g > Hungarian *g ~ Ob-Ugric *ɣ. Closely combing thru the vocabularies of these families (and, perhaps, Tocharian?) might even be able to turn up cognates for some of these words… though don’t hold your breath.
 I know there’s a handy paper covering this topic out there… but alas, I am failing to relocate it right now. Please drop me a hint in the comments if you have the reference at hand?
 Though there’s moreover Samic *moaŋkē ‘bent’, which seems difficult to integrate into any southeasterly loanword scenario.
 There are examples in the common Ob-Ugric lexicon — e.g. #asma ‘pillow’ — but these seem to be generally derivatives.
 This explanation does raise one question. Hungarian /z/ generally originates from Proto-Hungarian *ð, and a substitution *z > *ð would not seem particularly expected. Should we assume that [z] actually first originated as an allophone of /s/ before voiced stops in loanwords? There seem to be quite a few words in Hungarian with the cluster -zəg : -zg-, and various similar ones such as -zd-, though I do not know if any of these are a part of the language’s oldest loanword layer.
The first thing I’d suspect is that it’s not a split but a merger. I guess that can be ruled out?
On the one hand, attested Tocharian has no voice or aspiration contrasts whatsoever. On the other hand, this very feature (and apparently others) have been attributed to hypothetical contact with Uralic. On the third hand, why would Pre-Tocharian first donate voiced consonants and then lose them by contact to the same family… we’d need to posit two successive contacts with two different Uralic branches…
Yet other language families have been spoken by steppe nomads. At least one of the Xiongnu tribes spoke a Yeniseian language, if not Pre-Ket itself; and there’s a paper I need to find again… a golden bowl inscribed with Greek letters from southeastern Europe, attributed to the Avars, seems to attest a Tungusic language closer to Manchu than to the rest.
That’s hard to say. Reconstructing *ŋ₁ vs. *ŋ₂ would be an easy solution — but no Uralic language seems to show clear evidence for a tripartite distinction between these two and *ŋk.
Also, there are far too many “single-branch” irregular reflexes to be found across the Uralic languages for this to be a safe first approach. The history of the long vowels in Finnic, or Mansi *ś > *š, which have both been considered archaisms but currently seem explainable as conditional innovations, are good cautionary examples.
Another option is that yes, this is a split, but its direction has been misanalyzed: perhaps we are dealing with a Finno-Permic development *ŋk > *ŋ under certain conditions.
No need for hypotheses: it is already known from loanwords that Tocharian has been in contact with several Uralic branches: the three Ugric ones, Samoyedic, and possibly also Permic and Mari. It’s also the eastern end of this area where the absense of voiced stops has held out the best: they are still absent from Ob-Ugric, Forest Nenets, and Northern Selkup. It doesn’t seem too contrived to imagine that eastbound Tocharians might have run into Pre-Hungarians while still retaining PIE voiced stops, and only later lost them under Siberian Uralic influence?
Oh, awesome! I had no idea! :-)
I’ve found the pdf about the golden bowl that says:
+ ΒΟΥΗΛΑ · ΖΟΑΠΑΝ · ΤΕΣΗ · ΔΥΓΕΤΟΙΓΗ·
ΒΟΥΤΑΟΥΛ · ΖΩΑΠΑΝ · ΤΑΓΡΟΓΗ · ΗΤΖΙΓΗ · ΤΑΙΣΗ
The citation seems to be (it’s not entirely clear from the pdf):
E. A. Helimski (2000): On probable Tungus-Manchurian origin of the Buyla inscription from Nagy-Szentmiklós. Studia Etymologica Cracoviensia 5: 268–277.
Google fails to find the pdf, and I can’t remember where I downloaded it from. If you drop me an e-mail, I can send it to you.
Interesting considerations. In this connection I think it’s useful to draw attention to one word traditionally reconstructed with *-ŋ- that shows loss of nasality in Ob-Ugric: PU *poŋi(-s) ‘bosom’ > Khanty *puuɣǝl, Mansi *puut (from earlier *puwt).
This has an interesting Mordvin cognate: E pongo, M pov. Normally PU *ŋ seems to be preserved in Md only in final position. However, I’d suggest that here we have an intervocalic PMd *ŋ, showing the changes *ŋ > ŋk in E and *ŋ > v in M. There are also other words showing this correspondence, but none of them appear to have a reliable Uralic etymology.
In South Finnic the word shows a geminate -vv-: Vote pëvvi, Est põu (gen. põue). Clearly we have to reconstruct PFi *-vv- (*povvi) here to explain the reflexes. Other words showing the same correspondence are Finnic *savvi ‘clay’, *savvu ‘smoke’ and *ovvi ‘door / yard’. In the word for ‘smoke’ -vv- is also attested in the Jällivaara/Kurravaara subdialect of the Finnish Far Northern dialects.
On the Proto-Uralic level, perhaps we have to reconstruct a geminate *-ŋŋ- (*poŋŋi)? Then we could assume that in Ugric intervocalic *ŋ > *ŋk, but *ŋŋ was preserved; later *ŋŋ > *ŋ. Perhaps this hypothesis could also explain some of the other anomalous cases?
The later development *ŋ > Kh *ɣ in the word *poŋ(ŋ)i-s ‘bosom’ could perhaps be a result of secondary preconsonantal position, something like this: *poŋŋi-s > *poŋis > *puŋθ(V) >> *puuɣLV > *puuɣǝl (cf. PU *joŋsi ‘bow’ >> PKh *jaɣǝl).
I think I’d like to see the rest of the words before accepting this idea. If there were a soundlaw *ŋ > ŋg / V_V in Erzya, I’d expect this to show up in declensed forms of PMo *CVŋ roots. No such thing happens, though, cf. e.g. *koŋ “moon”: nom. /kov/, gen. /kovoń/, iness. /kovoso/…
A much simpler solution seems to be to assume that Erzya /poŋgo/ simply has the nominal suffix *-ka. And if there are too many examples to be explained in this fashion, it might be possible to consider Er. /ŋg/ ~ Mk. /v/ the reflex of some specific pre-Mordvinic consonant cluster.
I am not sure if Proto-Finnic *vv in these words is “clear”. They certainly seem like a distinct group; it’s particularly interesting to note that “bosom” and “door”, if reconstructed with single *w/*ŋ, would constitute exceptions to the monophthongization to *oo seen in *toxə- > *too- “to bring”, *loŋə- > *loo- “to shed, to create” (the front-vocalic counterpart *eŋə/*exə/*ewə > *öwə > *öö is regular as well)
Reconstructing *vv requires however addressing, firstly, the cases of *nëvvo “means”, *savva “pole”, which remain geminate in Finnish (neuvo, sauva). One possibility might be to assume *vv > v in Finnish only after a close vowel? Note also *vävvü “son-in-law” > Estonian väi, not ˣvävu; Finnish vävy. Votic vävü would have to be a loan from Ingrian.
The 2nd issue are the Germanic loanwords where *-aww- turns up as *-aav- (Fi. haava “wound”, kaava “formula”, naava “lichen on tree”, raavas “robust”), rather than *-avv- as might be expected if *-vv- was a possible Proto-Finnic cluster. I have two hypotheses for how these could be reinterpreted — either the “length metathesis” could be older than the change *ŋ > *w, and words with later *-vv- still had *wŋ (*ŋŋ?) by this time; or, alternately, since no Veps and Livonian cognates are known (Liv. ōv “wound” is clearly a loan from Estonian, on account of the lost final vowel), perhaps the words were instead loaned from Proto-Scandinavian: *-aggw- > PF *-akv-, with late vocalication to aa?
For the record, /vv/ also seems to remain in the southernmost Olonetsian dialects of Kotkatjärvi, Nekkula and Riipuskala — but only before /u/ or /y/, not /i/: savvu, vävvy, vs. povi, savi.
This does not seem to work too well, in light of two examples of Finnic singleton *v corresponding to retained *ŋ in Ugric: F *suvi ~ Kh *ɬoŋ etc. “summer”, and F *tüvi ~ Hungarian tő : töv- “base” (~ Permic *diŋ, Mokša *ťeŋ- > /ťej-/, so reconstructing *tüwə is not an option).
If a distinct medial has to be reconstructed for “bosom”, I’d suggest *wŋ rather than *ŋŋ. There does not seem to be good corroborating evidence for a gemination contrast for nasals in PU, while the cluster type glide + nasal has precedents in *ajŋə “brain”, *äjmä “needle”, *säwnä “ide” *wajŋə “spirit”, Finnic-Samic *śawŋa “pole”. (The last one has also been compared to Khanty *söɣ id., but it’s hard to say if this indicates *wŋ > *ɣ, a morphological analysis of the FS form as *śaw-ŋa, or in light of the front vowel, is an actual cognate at all. Northern Mansi /suuw/ is clearly to be considered a loan from Northern Khanty.)
A cluster *wŋ with a labial element might also explain the unexpected /m/ in Meadow Mari in this word: /poməš/, vs. Hill Mari /poŋəš/? The same correspondence can be also found in Mordvinic *toŋ ~ HiMa /toŋ/ ~ MeMa /tom/ “kernel”. (If Finnic *tuma ~ *tuuma belongs to this etymon, and if yes, if the *m corresponds to the Volgaic *ŋ, seems less clear. One alternative might be a suffixation *tuwŋə-ma > *tuwma/*tuŋma > *tuuma.)
I suppose a simpler explanation for these two words would be a development *ŋs > *ŋks > *ks, with *ŋ lost due to the Proto-Uralic disallowance of CCC clusters. This would require the *s element to have been a vocalic suffix added to a consonant stem, though: *po(ŋ/w)ŋə-sV > *poŋsV.
I additionally suspect that the *k here is a typical cluster epenthesis phenomenon, unrelated to the other cases showing apparent *ŋ > *ŋk, since the same also happens in Samic *jōksë, and later on in Mordvinic *joŋs > /joŋks/. If not though, “bow” would constitute an example of the lack of this change in Samoyedic (PSmy *jïntə).
I can’t remember all the cases with MdE -ng- ~ M -v-, but there’s also the homonymous verb stem E pongo- ~ M povǝ- ‘get (somewhere), come, hit, get stuck, etc.’. I forgot to mention that there is also an analogous correspondence E -ng- ~ M -j- after front vowels: e.g., E čenge-, M šäjǝ- ‘get burnt, burn badly, smolder’. This could be related Komi čïn, Udm čin, čïŋ ‘smoke’, Mansi *šiiŋkw ‘mist’ (PU *čäŋ(ŋ)i-?).
Finnish sauva and neuvo are not the same type of case as *ovvi, *povvi, *savvi and *savvu. There’s no reason to reconstruct a geminate for sauva and neuvo; instead, we can postulate PFi *sauva and *neuvo with a diphthong. There is a very clear phonetical difference between -uv- and -vv-, and such an opposition could well have existed in PFi. Compare the secondary opposition of -vv- and -uv(v)- in Finnish dialects with gemination before unstressed long vowels: /sauva/ ~ /sauvva/ ‘pole’ vs. /lavvaa/ PART ‘scaffolding’ (NOM /lava/).
The clearness of this hangs on /v/ being labiodental, though. I don’t think it’s plausible to posit this kind of a distinction having been in place further back, before the shift *w > *v. There is also no evidence for a Proto-Finnic phonemic distinction between *v and *u; *v is simply the non-syllabic allophone of *u before another vowel. That is, what I reconstruct as *savva must indeed have been pronounced [sauva]… but just as well, *povvi would have to have been pronounced [pouvi].
Also no distinction of an uv/vv sort seems to be actually found between the sauva type vs. the povi type in the cognates. Votic has not only põvvi etc., but just as well also savva etc, and even forms like sõvvan < *souðan “I row”. Evidently [vv] is a late assimilation from former [uv].
I admit my soundlaw *vv > *v before close vowels doesn’t quite make phonetic sense either, though. One kludge to keep these cluster types originally distinct might be to cut off any *ww-ish stage for povi entirely, to post-date the shift *ŋ > *w as even later than the separation of Central Finnic and Northern Finnic, and to posit *ŋŋ > *ŋ in NF before this? However, *ŋ > *w is a relatively early Finnic sound change and this dating would require reanalysing a vast number of other sound changes as parallel rather than inherited. Doesn’t seem like progress.
Naturally, an opposition between -vv- and -uv- is unlikely unless -v- was labiodental. But we find labiodental -v- in Finnic, Saami and Mordvin; as the closest language with -w- is Mari, the change *w > *v in the west is probably quite old. And of course, the opposition between *-vv- and *-uv- cannot as such be older than (Pre-)Proto-Finnic, as in earlier stages there were no diphthongs. A problem here is that we do not have a good etymology for either sauva or neuvo, so it’s unclear where this sequence -uv- comes from. The Saami and Ob-Ugric cognates proposed for sauva are in any case too irregular to be accepted (SaaN čávgŋi, SaaI čevŋi ~ čevnji ~ čevni, SaaSk caumm show irregular variation of both initial and medial consonants).
Of course, none of the cognates preserve the assumed distinction as such (-uv- vs. -vv-). But Finnish / Karelian still preserves a distinction (-uv- vs. -v-). I think this is hard to explain as secondary.
I don’t think this is a safe conclusion at all. The change *w > *v has occurred independently in scores of Eurasian language groups, e.g. most of Scandinavian (but not Elfdalish); German (but not English); Slavic; Romance (but not Latin); Greek (in αυ ευ); parts of Western Iranian such as Mazandarani (but not in others such as Balochi); most of Indic (but not Assamese); Hungarian (but not Ob-Ugric); Komi (but not Udmurt), in the case of Proto-Permic secondary *w; Livonian, in cases of word-initial breaking of Proto-Finnic *o such as vȯrābõz “squirrel”; Itelmen (but not Chukotkan); etc. This change may very probably have been independent in the three West Uralic groups as well, and cannot be easily dated.
As for what assuming a late date for *w > *v in the three West Uralic groups would gain? I suppose at least the epenthesis of *v before *oo in Samic and Finnic, or before *ü in Mordvinic, and its loss before other labial vowels, are better understandable if there was an intermediate *w stage to these developments. A separate change *w > *v is also required to account for the vocalization of *ŋ in Finnic in words like *suvi “summer”, *kevät “spring”, which could be identified with the shift of original *w to *v.
Given the [ʋ] in (even Vedic) Sanskrit, isn’t a reversal in Assamese more likely?
[ʋ] may generally throw a spanner in the works of hypotheses on the development of [w] and [v].
Do we know if Vedic had [ʋ]? We’re talking about a liturgical language that has been transmitted thru 2nd language speakers, who would presumably have switched from [w] to [ʋ] at the exact same time this change happened in the Prakrits, much like how pretty much no-one in Europe pronounces Liturgical Latin using [w].
Drawing conclusions about the phonetics of ancient written languages on the basis of living relatives or descendants is generally risky — as e.g. the case of Akkadian shows (“š” turns out to have been /s/, “s” turns out to have been /ts/, “q” turns out to have been /kʼ/, etc.)
I suppose a reversal in Assamese might be possible too, regardless. Also, on further reflection I realize I don’t even know if the /w/ in the language continues PIE *w at all! — it could be instead a secondary introduction from somewhere, after the widespread Indo-Aryan change to /b/ (which does seem to have occurred in the language in at least word-initial position: Wiktionary lists e.g. *vāyú > bayu “air”). Oops.
A little closer to home though, I today coincidentally noticed a mention in Sammallahti’s classic “The Saami Languages” that one of the Southern Sami dialects apparently has [w] instead of /v/. Seems like a potential archaism (and unlike Assamese, the language is not spoken right next to an area where /w/ starts again being the norm).
I just learned that Finnish itself has [ʋ].
…who believed that the pronunciation had to be precisely right for the prayers to work. I have of course wondered if the “these are tape recordings” interpretation is exaggerated, but there are things like allophony that is absent in Classical Sanskrit, the pitch accent, the transient development of phonemic overlong vowels, and the existence in Indian phonology of a term for alveolar as opposed to apico-dental consonants, and more that nobody could have made up.
Not only is this belief absent from Christianity, but so is the reliance on the spoken instead of the written word much more generally.
This is actually a case of basing conclusions on too few relatives (…Hebrew only, with gaps filled in from Arabic); comparing to South Arabian and Ethiopian languages would have helped (and later did help) a lot.
Forgot to mention – there are even Neo-Aramaic dialects left that retain ejectives; and others have deglottalized the ejectives, but the aspiration contrast to the “plain” voiceless consonants remains.
…The reconstruction of *wŋ seems to be also supported by Permic, in the case of two words:
Point 1: the development *o-ə > *ëë is normally only attested before consonant clusters. Reliable cases are *soskə- > *sëësk- “to chew”, *pončə > *bëëž “tail”. Probably also *čokkə > Komi /čëk/ “thick”, *kowsə > *kʷëëz “spruce”, and possibly moreover *owd₁əm > *wëën(m-) “drape”, *koskə- > ? *kʷëës- > Komi /kos-/ “to touch”. In open syllables, the most reliable Permic reflex seems to be *u: *čošə > *čuž “barley”, *jokə > *ju “river”, *šokə- > *šu- “to say”.
Point 2: *ŋ in Permic normally develops in accordance to the adjacent vowels, yielding /m/ only next to /o u/. Also, *ŋ ought to be retained in dialects of Udmurt. Here a development to *m seems to have instead happened already by Proto-Permic. We could assume an earlier development *wŋ > *m, similar to what I suggested for Meadow Mari. (And indeed, cf. Mari *tuməš “patch”, though for some reason here we have /m/ in Hill Mari too.)
“Bosom” itself, though, is strangely reflected as *pij in Permic.
I’m not sure we can plausibly postulate *-ow- in all these cases. As for the word for ‘opening, mouth’ (traditionally reconstructed as *aŋi), it would seem quite obvious to me that it is related to *aŋa- ‘open / take off’, for which we cannot postulate *-wŋ- in any case (cf. PFi *ava-ida- ‘open’ etc.). On the other hand, the Saami verb meaning ‘patch’ shows obscure variation between *tuovŋë-, *tuoŋŋë- and *tuoŋë-.
As to the other Permic examples you mention, Komi /kos-/ does not mean ‘touch’ but ‘to hit the bottom (of boat)’ instead, and moreover the data seems to be limited to a single attestation in the Sysola dialect – so I’m not sure this can plausibly be compared to Fi koskea ‘touch’. Interestingly the Saami cognate of koskea clearly had Proto-Saami *-sŋ- in light of West Saami cognates, so maybe we have to reconstruct Finno-Saamic *kosŋi-; but I know no other examples of *sŋ > Fi sk, nor any other examples of clusters of the type *s + nasal.
The following word would be an additional example of the correspondence discussed here: Khanty *ćorǝɣ- / Mansi *ćurɣ- / Hung csorog ~ csurog ‘run, drip, leak’. (UEW: 40 suggests some clearly wrong Finnic and Samoyed cognates to these; the Samoyed words reflect PSam *kürǝ-).
At the other end of Asia, the Tungusic language Nanai has /siŋgərə/ [ɕiŋgərə] meaning “mouse”. (/ŋ/, /ŋg/ and /ŋk/ all contrast between vowels.)
That’s a bit much for a coincidence, isn’t it?
S. Ko (2012): Tongue root harmony and vowel contrast in Northeast Asian languages. PhD thesis, Cornell University. Downloadable from here along with shorter papers that are more or less contained in the thesis.
D. Ko & G. Yurn (2011): A description of Najkhin Nanai. Altaic Languages Series. Seoul National University Press.
Indeed. It’s a common Tungusic word, approx. #siŋgərə (other cognates include e.g. Evenki /siŋərəkəːn/, Manchu /siŋgəri/), and I think anyone would agree that it’s most likely related in some fashion. Ural-Altaicists and Nostraticists of course default to thinking they’re common inheritance, but this also shows not much resemblance to the terms for ‘mouse’ in the other involved languages (at minimum Turkic *sïčgan; Mongolic *qulɢana; PIE *muHs), so loaning would most likely have to be kept on the table as well.
In addition to general Uralic – Tungusic parallels, there are also known cases of what look like loanwords between Proto-Tungusic and Proto-Samoyedic; or, even, Proto-Khanty and Proto-Tungusic (a classic example is PKh *jööŋ ~ PTng *joon ’10’). These are usually taken to have been borrowed as Tungusic → Uralic. It seems probable that either (pre-)Proto-Tungusic, or some suitably archaic (para-)Tungusic variety was once spoken further west… or, perhaps, that before the expansion of the Turkic languages, there once used to be Samoyedic or closely related Uralic varieties spoken further east in Siberia, which have relayed these loanwords to their western relatives. Just long-standing trade contacts across what is even today Evenki-speaking territory in central Siberia might also work, but perhaps that gets a bit contrived to maintain through millennia.