It's thinkable that the Tochariens either caused the split together with, or under preassure from, non-IE groups, or that they remain as trace elements (in the particle physics sense).
Imagine for example a wide dialect continuum, an incurser ripping right through, polarising one half that propels the other half far into the east, maybe T dragging S along with them in the wakes, never changing its own trajectory and polarity due to momentum, propelled ever further by repulsive forces.
The models East-West and Center-Periphery are not mutually exclusive, anyhow, e.g. in a radial diagram (using polar coordinates). Consider for example a shaded lamp, or the flame of a camp fire that has a well define center as well as top-bottom. That's an apt metaphor, because we only see shadows on the wall of a cave, in the platonic sense.
I don't want to go as far as to suggest a string theory of linguistics involving branes instead of branches. But dialect continuum is a common term of art, and wave-model an illustruous idea. In this context, comparisons to the particle-wave duality from physics have been drawn in the literature, indeed very dramatic.
There is a seizable ammount of apparent doublets in the PIE-Lexicon as reconstructed, some of which are better explained diachronicly. This is however difficult, if synchronic derivation on the PIE level remains a possibility, in light of ignorance, as much as obscure, naturalized and thus indescernable loans can hardly be accounted for, that would otherwise imply contact, but instead suggests unbroken descent through erroneous reconstruction (as finding a phoneticly plausible cognate with however far fetched semantic derivation is possible 50% of the time, and if not, a shape-shifting monstrum of a phoneme like *gwh- may be conjured).
Based on the phonetics of the Glottalic theory after Gamkrelidze and Ivanov, an apparent grouping of Germanic, Armenian and Hittite has been proposed (Gamkrelidze 2010: In defense of Ejectives for Proto-Indo-European). Kammerzell (1999: Glottaltheorie) gives diagramms for a general overview. Kortlandt put some of the theory to good use for Slavic accentology (cf. Dercksen in the introduction to their dictionary). Other's argue--vehemently--that this theory is chasing ghost images.
A recent, indecicive comment on branches and Tocharien's position in the "tree" (as opposed to "gammut", e.g.) is from Michaël Peyrot (2019: Indo-Uralic, Indo-Anatolian, Indo-Tocharian)
it [Tocharien] is often assumed to have been the second branch to split off after Anatolian, as in the tree reconstructed by Ringe, Warnow & Taylor (2002: 87; see figure 13.1, next page).
Several authors have argued that Tocharian was the second branch to split off […]. Yet, the evidence is not overwhelming, and, strikingly, many authors strongly differ in the arguments they adduce for this position of Tocharian in the family tree.
Further down, Peyrot follows Kloekhorst (2008) through barely seven points as evidence for a Indo-Anatolian divide. This is questionable though, first of all because they have a tendency to assume Hittite retained more archaisms, leading to the proposal of a common innovation in the others, and thus the appearance of a solid core PIE. Second, the individual examples are tailored to support the assumption. This isn't necessarily wrong if it's done systematicly. However, seven individual lexical examples are not yet a system. Whether the points are particularly strong, I am not aware of any criticizm either way; though Peyrot would likely have mentioned it after eleven years, if anything of substance turned up. #7. "horse" might be particularly instructive, if they rode out immediately after breaking the horses in the Steppe for the first time; Als, the Kurgan Hypothesis is just a hypothesis; Kroonen et al (ref?) evaluated theories after genetic evidence found south of the Caucasus promised new perspectives; Further, supposed eastern connections to horse words in e.g. Mongolian and Chinese require more research (attempted by Blazek and Schwartz 2017), precisely because Macro-Altaic is a burned bridge in the wider community by now. #1. "disappear" / "die" is pretty close to "forget"
farāmūšīdan cognates with Lithuanian užmiršti/pamiršti, Latvian aizmirst/piemirst, old Armenian moṙanam, Tocharian A märs- all of them meaning to forget
(reddit with discussion and link to helsinki.fi)
This might look derivative, especially with the here not further to be specified preverb. Peyrot seems to put a lot of weight on stems, as is evident further down:
One of the frequently cited Hittite-Tocharian matches is Hitt. eku-zi / aku- ‘drink’ ~ Toch.AB yok- ‘drink’ < *h₁egwh- (Pinault 2006: 93). Although Anatolian and Tocharian are indeed the only two branches in which this verb is found, and most other branches have reflexes of the more common *peh₃- ‘drink’, this etymon is difficult to use as an argument for the Indo-Tocharian hypothesis. Most importantly, even though Anatolian and Tocharian are the only branches in which *h₁egwh- is attested, reflexes of this root are also found in Lat. ēbrius ‘drunk’ and Gr. νήφω ‘be sober’.
That might take a second to sink in.
A pro pos: One problem of the comparative method is that reanalysis carried out with technical perfection should appear like a proper root to be thus indescernable. The other problem is that the selection of comparative material is subject to intuition, and that this intuition is frequently misleading--an argument more often leveled at long range comparisons (e.g. Japanese-Hebrew)--and has to withstand falsification. The Greek looks easily associated with *peh3-; The Latin is reminiscent of brew. On the other hand, German einen heben "to drink [liquor], chug [bear]" and Humpen "jug" could be compared, the same way that Upper German n. Fetzen 1 "buzz [from liquor]" 2 "jug" might compare to *peh3---not reliable. They further treat tentative Indo-Uralic reconstructions, hinging on "the inclusion of Proto-Samoyedic *e̮- among the cognates" [diacrit omitted] in meticulous detail, which, they admit, rests yet on too many unknowns. Thus there is no solid limit to the reconstruction. It defies believe how far one would have to go. Usually the grammatic typology is deemed more reliable; Comparative grammar is lagging far behind the lexical reconstruction however. Just to stay with lexis for a moment longer:
a) I had mistakenly considered toxic, intoxicated (viz inebriated), as I hadn't noticed the gloss for "PFU *toxi-", that is "‘bring’", which would make the comparison unlikely, but, as I had at the same time considered that Humpen "jug" would remind of En. hump, Ger. humpeln "to limp", further bump, and fuzzy memories of roots in *bh-, as well as jug that is of uncertain origin with one variant that reminds of goble, goblet, I had nearly set out to see how PFU *t and *j should relate, and ... there it is: "from ... τοξικόν (toxikón) [φάρμακον (phármakon)] ("poison for use on arrows")", which "Pokorny (1959) connects it to the Greek root φαρ- as in φάρος (pháros, “plough”) and φάρυγξ (phárunx, “throat”), from a Proto-Indo-European *bʰer- (“to cut, pierce, scrape”) ..."; that's uncertain, but suits me, because *bʰer- is of course also glossed "carry" (cf. to bear). Cracking the Jackpot! Lat. fero "to bring" supposed from the same root, is a highly synthetic, suppletive paradigm with tol- in perfect; *bher- has a doublette in *dher- ... The point being, the third problem of the comparative method is that there are no rigid laws for semantic derivation. That's not actually a problem, rather the strength well of language to beginn with. However, the comparative method makes no promise to disentangle the ensuing mess. Rather, many etymological dictionaries try to isolate only the most stable roots. Naturally, dialectal differences are due to instabilities in the system and therefore barely tangible in its rigid framework. The exclusionary premisses that Mycenean Greek had no relation to Finnic is likewise intangible: it's simply not a question of linguistics. Meanwhile, Finns are belittled who try working out evidence of Greek culture in old Finnland. b) no less speculative, it should be doubtful whether above mentioned "Tocharian A märs-" (to forget) etc., if it rather belonged with √mrs
PIE √mrs- √mors- √mers- (a.) ‘falsch, umsonst, vergeblich’ [ie.: false, for nought, to no avail -- vectory]
RV. mŕ̥sā(adv.) ‘umsonst, vergeblich’
AV. mŕ̥sā(adv.) ‘in falscher Weise’
OHitt. maršei-(vb.1.) ‘falsch (betrügerisch) werden’
(Pyysalo et al, Proto-Indo-European Lexicon, The generative etymological dictionary of Indo European languages, with further references)
How that in turn related to √mr- might be a matter of grammar, after all.
šīdan (cp. farāmūšīdan above) is a verb in modern Farsi itself, for example. Similarly, *bher- and *dher- might simply contain a common element; Whether fara-, En. fore- and similar can count as a stem is debatable (cf. e.g. Georg Dunkel 2014, Cyril Bosch 2013).
We can further compare to miss, Ger. vermissen "to have lost, to desire, to miss (smb.)", to dismiss, Lat. mitto "to send", all PIE *meyt- (“to change, exchange, trade”) [wiktionary], further OE mete "decide", to meat [a decission], further Ger. ausmisten "to clean out", Mist "dung, trash", Miete, Misthaufen "heap [of hay, dung]" (Lat. meta "conic structure"), reasonably so if backed r modulo sonority gives high vowels, i, y. We can compare Ger. fallen "to fall, to die [in battle]", fehlen "be missing", Fehler "mistake", falsch "false" (Lat. falsus), etw. fallen lassen wie eine heiße Kartoffel (to drop something like a hot potato), Befehl "command, order" (viz message), and feilschen "to barter" (viz exchange, trade) for analogy, or tauschen "exchange", täuschen "deceive", tuscheln "to whisper (conspiratively), further untertauchen "to dive under" (to lay low, disappear), or En. to loose, lose, Ger. (ver)letzen "to hurt, damage" (lose a limb), Leid "suffering", Beleidigung "insult", ledig "lone, alone", further los "up, away", lösen "solve", let's (and all that jazz which is apparently far from related, lex, letter, Erlass, lassen, leave, Leiche "corpse", belegen (mit einem Bann, Fluch), lenis, lead), or verzeihen "apo-logy", verziehen "retreat" (already dissimalar in oldest evidence), verzichten "to pass, forefit, dismiss", Zeche, Zuchthaus etc. etc. The level of convergence in this is immense).
Kloekhorst rather argues that the sense "to die" were not found in the Anatolian branch, because it hadn't yet existed, though it's existance in many other branches is possibly borrowed and a common innovation for PIE/Anat. not even that secure. I'm might be wrong on that, but I'm sure the car died on me is a secondary anthropomorphism, and you are dead (to me) either an empty threat, figurative speach, or a judgement call. As said, it's pretty much useless to argue on that level, if there's hardly any expectation of ehh, regular semantic shift. Romans deemed social death a suitable metaphor, economies in general have appreciate the labour potential of prisoners more valuable than capital punishment, and Gökli Tepe was decorated with human skulls, but that says very little, as godkings don't die, they arrange for the ultimate ascend.
Nevertheless, Anatolian ist commonly assumed to be the most distant branch, and these proposals need to be put out to advance the theory.
- A matter that rather belongs with comparative etymology is god, vs deus, theos, and bog, the latter in Slavic, Iranian and Sanskrit, as far as I know.
Similarly, words for king should be instructive. The root *Hregs is clearly PIE for what it's worth, but the history of the term rex needs details. Hittite didn't have it as such. Ragnaröck is not clearly recognizable as King of kings anymore either.
- Thracian language is so barely known that it's not even clear which branch it should be.