When we consider the known patterns of CV reduplication in Indo-European, we find that different reduplicated adjectives or nouns with very similar meanings can be derived in parallel from the same verb root. One pair already mentioned is Vedic sásni- (a cákri-type word) : siṣṇú-, both from the verb root *senh₂- ‘gain, strive after, accomplish’. Both adjectives mean, approximately, ‘constantly gaining/winning for oneself or others’. No CV-reduplicated present derived from this root is attested. It forms an Indo-Iranian reduplicated perfect (which, however, expresses a completed action and has no iterative or habitual connotations), and a Vedic “intensive” present with full reduplication (which does mean ‘gain/acquire repeatedly’ but is structurally different from the adjectives in question). It is possible, however, that once a productive derivational schema became established, it was not essential that an actual CV-reduplicated present should exist. E(e)-R(ø)-i- or E(i)-R(ø)-u- adjectives, as well as E(e)-R(ø)-o- (*kʷékʷlo-type) nouns could be formed directly on the basis of a verb root. In one of the Rigvedic hymns to Indra (Book 6, 23:4b) the god is described as follows:
babhrír vájram papíḥ sómaṃ dadír gā́ḥ
(doing all these things habitually, i.e. whenever he comes to attend a soma-pressing). We have no fewer than three cákri-type quasi-partciples here. Note that they take accusative objects, like the corresponding verbs. And yet, although all the three verbs form CV-reduplicated presents in Vedic, the adjectives can’t be derived directly from those presents. The Vedic present of *bʰer- ‘carry’ (3sg./3pl.) is bi-bhár-ti /bí-bhr-ati with an i-reduplication; from *poh₃(i)- ‘drink’ we have pí-b-a-ti/pí-b-a-nti. At least in the latter case both the i-reduplication and the voiced *b (by assimilation, from the sequence *-ph₃-, with a voiced laryngeal) are very old, at least as old as the common ancestor of Vedic, Latin and the Celtic languages. The adjective papí- seems to have been formed directly to the Indo-Aryan root pā-/pī-, using the cákri-type template. The type itself is probably an Indo-Iranian innovation (especially productive in Vedic), inspired by the use of *-i- rather than *-o- as the final vowel in compound stems. The precursor of the cákri-type is essentially identical with the *kʷékʷlo-type (except perhaps for an accentual contrast between nouns and adjectives, if the final accent of bhabhrí- is original and the initial one in cákri- is a Vedic innovation). Therefore the formation represented by bhabhrí- is a reworking of an older type which can be reconstructed as *bʰe-bʰr-ó- ‘(ever-)carrying’ – or, when substantivised, *bʰé-bʰr-o- ‘habitual carrier’. A parallel u-stem with practically the same meaning may also have existed, either *bʰi-bʰr-ú- (like Ved. siṣṇú-) or possibly *bʰe-bʰr-ú- (like Ved. (pari-)tatnú- ‘surrounding’). Thus, both the *Ce- ~ *Ci- variation in the echo and the coexistence of stems in *-o- and *-u- can be explained with recourse to known Indo-European word-forming processes.
Two well-known Indo-European semiaquatic mammals
Conrad Gessner, De piscium et aquatilium animantium natura
But wait a moment: *bʰé-bʰr-o- and *bʰi-bʰr-ú- look exactly like the reconstructed variants of the ‘beaver’ word. If beavers owe their Indo-European name not to their coat colour but to some characteristic habitual activity, the verb describing that activity should be similar to *bʰer- ‘carry’. There are, for example, a couple of known roots of the shape *bʰerH-, one meaning ‘cut, strike, pierce, fight’ (with an unspecified laryngeal) and the other ‘move rapidly, rush, chase’ (in which *H = *h₂ or *h₃). The laryngeal would have been lost in a reduplication containing the root in zero-grade, so we would not be able to see any difference between the outcomes of *-bʰr- and *-bʰrH-.
Stretching the imagination a little, one would be able to connect the meaning of any of these roots with the beaver’s habits. For example, the first *bʰerH- is glossed ‘mit sharfem Werkzeug bearbeiten’ in the LIV; and what are the beaver’s incisors if not “ein sharfes Werkzeug”? Still, I would like to defend the simplest solution, involving the most widespread and most securely reconstructed of these roots, namely *bʰer- ‘carry’. I will justify my preference in the next post. Here, let me only point out that no matter which root we choose, it makes sense to assume that there were more than one related but independently formed variants of the beaver’s name already at a very early stage – at least *bʰébʰros and *bʰibʰrús. It seems that both of them were inherited by languages ancestral to some of the branches of Indo-European. Their visible relatedness, and perhaps the existence in some branches of recognisably related reduplicated verb forms could have produced still more variants through a kind of lexical cross-pollination, hence the attested variation of the echo vowel, the stem class, and the accentuation.
 Reduplication in verbs will be discussed in blog posts to come.
 They are accented on the stem vowel, unlike cákri- itself, but the accentual variation looks random and is not correlated with any functional difference.
 With the root syllable accented in the Rigveda. Later the accent was shifted to the echo syllable: bhíbharti.
 When not reduplicated, the Vedic present (bhárati) usually has a telic meaning, i.e. ‘bring’ (a complete one-time activity) rather than ‘carry, bear, wield’.
 The original forms were *pí-ph₃-e-ti/*pí-ph₃-o-nti, with the second *p realised as [b].
 Cf. Germanic *tetru-, *tetru-ka- (or *titru-ka-?) ‘skin disease, scabies’ (OE teter, Mod.E tetter, OHG zitaroh), Sanskrit dadru-, dadrū (f.) ‘leprosy’, apparently from *der- ‘tear, flay, peel’.
 That is, ‘work on (something) with a sharp tool’ – a bit conjecturally, to be sure, since most of the attested meanings suggest the use of a weapon rather than a carpenter’s tool, or are figurative: ‘scold, rebuke’, etc.