Editing Celtic languages (section)

=== Eska (2010) ===
Eska<ref>Joseph F. Eska (2010) "The emergence of the Celtic languages". In Martin J. Ball and Nicole Müller (eds.), ''The Celtic languages''. Routledge. {{ISBN|9781138969995}}</ref> evaluates the evidence as supporting the following tree, based on [[comparative method#Terminology|shared innovations]], though it is not always clear that the innovations are not [[areal feature]]s. It seems likely that Celtiberian split off before Cisalpine Celtic, but the evidence for this is not robust. On the other hand, the unity of Gaulish, Goidelic, and Brittonic is reasonably secure. Schumacher (2004, p.&nbsp;86) had already cautiously considered this grouping to be likely genetic, based, among others, on the shared reformation of the sentence-initial, fully inflecting relative pronoun ''*i̯os, *i̯ā, *i̯od'' into an uninflected enclitic particle. Eska sees [[Cisalpine Gaulish]] as more akin to Lepontic than to Transalpine Gaulish.

{{Tree list}}
*'''Celtic'''
**[[Hispano-Celtic languages|Hispano-Celtic]] {{extinct}}
***[[Celtiberian language|Celtiberian]] {{extinct}}
***[[Gallaecian language|Gallaecian]] {{extinct}}
**[[Nuclear Celtic languages|Nuclear Celtic]]
***[[Cisalpine Celtic]]: [[Lepontic language|Lepontic]] → [[Cisalpine Gaulish]] {{extinct}}
***Core Celtic (secure)
****[[Transalpine Gaulish]] {{extinct}} ("Transalpine Celtic")
****[[Insular Celtic languages|Insular Celtic]]
*****[[Goidelic languages|Goidelic]]
*****[[Brittonic languages|Brittonic]]
{{Tree list/end}}

Eska considers a division of Transalpine–Goidelic–Brittonic into Transalpine and Insular Celtic to be most probable because of the greater number of innovations in Insular Celtic than in P-Celtic, and because the Insular Celtic languages were probably not in great enough contact for those innovations to spread as part of a [[sprachbund]]. However, if they have another explanation (such as an [[Subject–verb–object|SOV]] [[Stratum (linguistics)|substratum]] language), then it is possible that P-Celtic is a valid clade, and the top branching would be:

{{Tree list}}
*Core Celtic (P-Celtic hypothesis)
**[[Goidelic languages|Goidelic]]
**[[Gallo-Brittonic languages|Gallo-Brittonic]]
***[[Transalpine Gaulish]] ("Transalpine Celtic") {{extinct}}
***[[Brittonic languages|Brittonic]]
{{Tree list/end}}