In the Samic languages, the second part of these remains phonologically a consonant, and can thus close the syllable before it, triggering the weak grade.
In Finnic, on the other hand, these were treated as diphthongs, and were equivalent to long vowels in terms of syllable structure.
In all languages that retain it, however, it has evolved further to a less predictable system of consonant mutation, of morphophonological or even purely morphological nature.
In addition, not all Finnish words that hypothetically could have gradation undergo it: for instance, the genitive form of auto 'car' is auton.
Three broad positions may be distinguished:[1] In all three groups, consonant gradation has the same conditioning, the distinction between open and closed syllables.
In this light, and in the absence of any evidence of the same system having existed in any unrelated language in the world, Helimski (1995) has argued that the latter two options should be rejected as implausible.
[2] If a connection exists, it is also disputed what its nature may be, again allowing for three broad positions: The great geographical distance between the Finnic and Samic peoples on one hand, and the Nganasans on the other, leads Helimski to reject the second option of these.
The original effect of gradation in the Finnic languages can be reconstructed as a lenition of the consonant at the beginning of a closed syllable.
Moreover, only the last member of a consonant cluster was subject to gradation, and single stops and affricates were only affected if they were not adjacent to another obstruent.
[3] This type of gradation only systematically appears in cases of word-final *s, which between vowels uniformly becomes *h: Finnish pensas 'bush' has the genitive pensaan < *pensahen.
Veps and Livonian have largely leveled the original gradation system, and reflect both weak and strong grades of single stops as /b d ɡ/; this may be an archaism or a substitution of voiced stops for fricatives due to foreign influence (Russian for Veps, Latvian for Livonian).
The conditioning of syllable structure is still visible in most cases, but it is no longer productive: gradation has become a grammatical feature.
Patterns include t : d (tietää : tiedän), rt : rr (kertoa : kerron), lt : ll (pelto : pellon), and nt ~ nn (antaa ~ annan).
Quantitative consonant gradation has expanded to include in addition to the pairs kk : k, pp : p, tt : t, also gg : g and bb : b (but not dd : d) in a number of recent loanwords, such as blogata : bloggaan 'to blog'; lobata : lobbaan 'to lobby'.
The imperative form of verbs also ended in a now-lost -k. For examples, side 'bandage', from *siðe, earlier *siðek (cf.
In the case of verbs like tulla 'to come', the earlier form was *tul-ðak, but the *ð was assimilated to the /l/ according to the patterns described above.
The original strong grade was preserved in verbs like hais-ta 'to stink' since gradation did not take place when a consonant followed /s/.
The h is preserved after stressed syllables, as in maahan 'into the land' (from maa), but lost otherwise as in kotiin 'into the home' (from earlier *kotihin, from koti).
This is particularly visible in forms that display a strong grade where a weak would be historically expected, or vice versa.
Several recent loans and coinages with simple /p, t, k/ are also left entirely outside of gradation, e.g. auto (: auton) 'car', eka (: ekan) 'first', muki (: mukin) 'mug', peti (: petin, sometimes pedin ) 'bed', söpö (: söpön) 'cute'.
While the partitive plurals of kana 'hen' and lakana 'bedsheet' still show distinct treatment of the original *-ta (kanoja, lakanoita), the partitive singulars in modern Finnish both have the weak grade (kanaa, lakanaa), although in several dialects of older Finnish the form lakanata occurred for the latter.
On the other hand, some Karelian dialects (such as Livvi or Olonets) do not allow for gradation in clusters beginning on nasals.
The Karelian phoneme inventory also includes the affricate /tʃ/ (represented in the orthography as č), which may be found geminated and is such subject to quantitative gradation: meččä 'forest' → mečäššä 'in (the) forest'.
In the Western dialects, there are several possible weak grade counterparts of tš: Further minor variation in these gradation patterns was found down to the level of individual villages.
Another extremely important feature of Estonian gradation is that, due to the greater loss of word-final segments (both consonants and vowels), the Estonian gradation is an almost entirely opaque process, where the consonant grade (short, long, or overlong) must be listed for each class of wordform.
In Kildin and Ter Sami, this merger did not affect stops and affricates, due to the additional preaspiration found on original geminates.
In the others, the merger affected stops and affricates as well, with the strong grade of singletons receiving secondary preaspiration.
In the languages in closest contact to Finnic (Northern, Inari and Skolt), a number of developments towards the situation in Finnish and Karelian have occurred, such as the change of unlengthened *t to /ð/.
Note that the following apostrophe marking the over-long grade is not used in the official orthography, although it is generally found in dictionaries.
In certain environments, geminate stops can alternate with short (allophonically voiced) ones, under the usual conditions for radical gradation.