The origin of the Tocharian A plural ending - äṃ

The aim of the present article is to trace the origin and the evolution of the Tocharian A ending - äṃ , which is the plural marker of a closed class of nouns, whose Tocharian B counterparts are ranged under other inflectional classes. The results of this investi-gation are twofold: (1) not only is Tocharian A shown to have generally preserved the Proto-Indo-European situation better than Tocharian B, (2) but it is also argued that some members of this closed class are relevant from an Indo-European comparative perspective, since they have refunctionalised the n -form of the PIE * r / n -stems as a plural marker.


Introduction
In contrast to the verbal system, it is generally held that the Tocharian nominal system is less conservative and archaic with respect to what is reconstructed for Proto-Indo-European. This is, however, only partially true. Some Tocharian nominal endings and forms can in fact prove relevant from a comparative perspective. I believe this is the case with the Tocharian A inflectional class with the plural ending -äṃ (nom. = obl.). This case marker is historically compared with TchB -na, as they are usually considered to be the outcome of the original neuter plural of nasal stems, which underwent reanalysis: PIE *-n-h2 > *-n-ă > PTch *-na > TchB -na, A -(ä)ṃ (Pinault 2008: 493f.). For this reason, Krause & Thomas (TEB § 162) grouped nouns with these plurals together under a single nominal class (II.1). Despite the alleged common origin, however, TchB -na and TchA -äṃ have a different distribution. Indeed, there are no Tocharian B nouns with plural in -na matching Tocharian A nouns with plural in -äṃ. Their productivity is different as well: TchB -na is the plural marker of a fair number of nominals, while TchA -äṃ is confined to five substantives only. This mismatch is peculiar. As can be seen from Table 1, the cognate nouns in Tocharian A and B belong to different inflectional classes.
The core issue is which of the two languages preserves the older state of affairs, and the present article aims to answer this question, analysing the synchronic distribution and the diachronic evolution of this ending in Tocharian. I intend to show that Tocharian A has generally preserved the original situation, while Tocharian B has mostly recharacterised the plural form of these nouns. If my analysis is correct, it would also confirm that this inflectional class is relevant to the reconstruction and the further development of an archaic Proto-Indo-European class of nouns: the *r/n-heteroclites.

Etymology of the nouns
Three of the five Tocharian substantives that belong to class II.1 can be traced back to PIE heteroclites.1 They are: TchA por, B puwar 'fire' , TchA ysār, B yasar 'blood' , and TchA ytār, B ytārye 'road' . That these nouns reflect PIE *r/n-stems was actually noted decades ago, but the relevance of this fact for their plural formation has not, to my knowledge, been explicitly pointed out.
Finally, both TchA ytār and TchB ytārye /y(ə)tárye/ 'road, street, path' are of feminine gender. These words must be compared with Lat. iter, gen. itineris, and the derivative YAv. pairiθna 'the course of life' (Yt 8.54, Panaino 1990: 141).3 Tocharian continues the collective PIE *h1i-tṓr (Hilmarsson 1986: 44;Pinault 2011: 163-164;Adams DTB: 559;Kim 2019: 145).4 The unexpected feminine gender in both Tocharian A and B, and the element -ye /-(ə)ye/ in Tocharian B are problematic.5 Indeed, this noun should be reconstructed as neuter for Proto-Indo-European. It follows that the feminine gender of TchA ytār, B ytārye must be secondary, because PIE neuter nouns are usually continued as alternating in Tocharian. In my opinion, in the Proto-Tocharian phase, this substantive was influenced by the ancestor of the productive feminine noun TchB kälymiye, A kälyme 'direction, region' because of its meaning, so that PTch *yətar at first acquired feminine gender. Since the gender of TchA kälyme also fluctuates between alternating and feminine (Carling 2009: 176;Peyrot 2012: 212), one might assume a case of mutual influence. Subsequently, after the dissolution of Proto-Tocharian, it shifted inflectional class in Tocharian B, becoming a noun of the kälymiye-type.6 Indo-European Linguistics 7 (2019) 1-12 The two last substantives that belong to Class II.1 are TchA wram, TchB°w reme 'thing, object, matter' and TchA plāc, B plāce 'word' . They do not go back to heteroclitic stems.

3
Origin of the plural ending TchA -äṃ There are two opposing ways to explain the plural forms of the nouns discussed above: (1) either Tocharian B has preserved the original situation and Tocharian A has introduced the morpheme -(ä)ṃ < PTch *-na from other stems, or (2) Tocharian A has preserved the original situation and in Tocharian B the nasal plural *-na has been lost. At first sight, both hypotheses seem plausible. The former implies that Tocharian A actually inherited plural forms identical to those of Tocharian B. When final vowels were deleted in Pre-Tocharian A, nominative and oblique would have become homophonous in both the singular and the plural. In order 7 I see no reason to reconstruct either Pinault's *u̯ r̥ h1-o-mo-(2008: 512) or Adams' *u̯ rē-mēn-(DTB: 672). Although these preforms have the advantage of deriving both Tocharian A and B words from a common ancestor, the former does not take into account the unproductive plural ending TchA -äṃ, while the latter requires an unwarranted lengthened grade in both the root and the suffix. 8 See further Malzahn & Fellner (2015: 72 fn. 36). In the same inflectional class, we also find TchB maśce 'fist' , which is to be equated with IIr. *musti-'fist' (cf. Skt. muṣṭí-, Av. mušti-), although the Tocharian word continues a nom.sg. PIE *-tē(i̯ ) of the hysterodynamic type, instead of the expected *-ti-s in Indo-Iranian (Pinault 2013: 346f.; Adams DTB: 476).
to reintroduce a distinction between singular and plural, the plural morpheme -äṃ would have been attached at a later stage (e.g. pl. PTch *yəsara > Pre-TchA *ysār >> TchA ysāräṃ). This hypothesis also has to cope with some problems, however. As stated in the opening section, the fact that the marker TchA -äṃ is the least productive among the plural endings of Tocharian A must be seriously considered if its origin is to be traced. As a consequence, analogical developments can hardly be involved: basically, there is no immediate source where the plural *-äṃ could have been abstracted and then generalised.9 I therefore believe that the latter scenario is the correct one, since it lends itself to a more elegant solution: the nasal element in TchA -äṃ must be interpreted as an archaism not only in TchA wram 'thing, object' , which goes back to an old *men-stem, but also in those words that continue heteroclitic *r/nstems, where the plural -äṃ historically coincides with the original n-form. It follows that Tocharian A, as opposed to Tocharian B, has continued the heteroclitic inflection, by refunctionalising the n-form of the oblique cases in the plural. This is not an isolated trend of development, since it closely resembles similar cases in Latin and Iranian.
In the history of Latin, the old heteroclites are normalised in two ways (Ernout 1914: 67-68;Leumann 1977: 359-360;Weiss 2009: 240 f.). On the one hand, some nouns have analogically levelled the r-stem in all cases (e.g. Lat. ūber, -eris 'udder; abundant' , cf. Skt. udhar/n-'udder'), although in Old Latin a few of them were still heteroclitic. Compare, for instance, Lat. femur, gen. femoris 'thigh' (e.g. in femore, Cicero, Verr. Or. IV. 43, 93) with OLat. femur, gen. feminis 'id.' (e.g. femina in Plautus, Poen. 3.1, 68). On the other hand, nouns like iter, gen. itineris 'street, way, journey' or iecur, gen. iocineris 'liver' show spread of the r-stem from the strong cases to the n-stem of the weak cases. It follows that in the pre-history of Latin two paradigms of the word for 'way, street' can be virtually reconstructed: older *iter / *itinis and newer *iter / *iteris (Leumann 1977: 103). Latin speakers mixed up the two paradigms, forming a new inflection with a stem *itin-er-, from a pre-existing *itin-, in all weak cases and in the plural. Only the nominative and accusative singular still attest the original distribution of the allomorphs. 9 An anonymous reviewer points out that TchA -äṃ could have been introduced from the neuter nasal stems. However, the only noun that diachronically goes back to a *men-stem and synchronically shows this ending is namely wram 'thing, object' , because other continuants of the PIE *men-stems have replaced their original plural forms, like TchA ñom 'name' , pl. ñomäntu (cf. TchB ñem, pl. ñemna < PTch *ñaemna). This evidence implies that *-äṃ was not a convenient plural ending in Pre-Tocharian A. There is therefore no reason why words like TchA por 'fire' , ytār 'road' , and ysār 'blood' should have selected this ending, and not other much more productive plural markers.
A similar analysis, mutatis mutandis, also accounts for TchA wram 'thing, object' , whose plural wramäṃ may go back to *u̯ réh1-mn-h2 > *wrēmnă > PTch *wŕaemna. On the other hand, I was not able to find any clear explanation for the plural plācäṃ 'words' (cf. plācänyo 'because of words' in e.g. A75 b6). Indeed, among the words discussed above, this is the only case where Tocharian B attests remnants of the original inflection (cf. nom.pl. TchB plāci < PTch *pəlacəyə < PIE *(s)plH-tei̯ -es). A tentative analysis suggests that TchA plāc acquired the plural ending from TchA wram. The reason this analogical development took place lies in the meaning of these nouns. Indeed, TchA wram had to originally mean 'speech, word' , as the etymology of the term seems to indicate. For a certain period, TchA wram and TchA plāc were consequently almost synonyms, and this has favoured the transfer of the ending -äṃ to the paradigm of plāc. Only at a later time would TchA wram have developed the meaning of 'object' . 12 One may wonder whether this phenomenon can be regarded as a process of exaptation, a term introduced into linguistics by Lass (1990), according to which linguistic relics can be refunctionalised by being adapted according to existing regular templates.

Conclusion
This article has focused on the diachronic evolution of Tocharian A nouns with the plural ending -äṃ. With the exception of TchA plāc 'word' , we have seen that these substantives can be traced back to PIE *r/n-stems (TchA ytār 'road' , ysār 'blood' , por 'fire') and to PIE *men-stems (TchA wram 'thing, object'). My final aim was to demonstrate that the plural ending TchA -äṃ constitutes a precious archaism that in a way continued the Proto-Indo-European state of affairs. We have seen that the reconstruction of heteroclitic nouns requires strict comparisons between the older stages of the Indo-European languages, because in more recent times the same languages generalised one of the two stems.
In Tocharian B we found precisely this development: the formal contention between r-and n-stems was resolved with the victory of the former over the latter. The final result of this process caused the collapse of the n-stem. On the other hand, we have seen that Tocharian A preserved the older state of affairs, since it has maintained both the r-form of the singular and the n-form of the plural. The final outcome of this development is a blended plural with the rform as the stem and the n-form as the ending. This inflectional class therefore constitutes an important section of the Tocharian lexicon that offers a small but significant contribution to the diachronic evolution of Indo-European nominal morphology.