Italo-Celtic

In historical linguistics, Italo-Celtic is a grouping of the Italic and Celtic branches of the Indo-European language family on the basis of features shared by these two branches and no others. There is controversy about the causes of these similarities. They are usually considered to be innovations, likely to have developed after the breakup of the Proto-Indo-European language. It is also possible that some of these are not innovations, but shared conservative features. What is commonly accepted is that the shared features may usefully be thought of as Italo-Celtic forms.

The traditional interpretation of the data is that these two subgroups of the Indo-European language family are generally more closely related to each other than to the other Indo-European languages. This could imply that they are descended from a common ancestor, a Proto-Italo-Celtic which can be partly reconstructed by the comparative method. Those scholars who believe Proto-Italo-Celtic was an identifiable historical language estimate that it was spoken in the third or second millennium BC somewhere in south-central Europe but this hypothesis fell out of favour after being reexamined by Calvert Watkins in 1966. Some scholars, such as Frederik Kortlandt, continued to be interested in the theory. In 2002 a paper by Ringe, Warnow, and Taylor, employing computational methods as a supplement to the traditional linguistic subgrouping methodology, argued in favour of an Italo-Celtic subgroup, and in 2007 Kortlandt attempted a reconstruction of a Proto-Italo-Celtic.

The most common alternative interpretation is that the close proximity of Proto-Celtic and Proto-Italic over a long period could have encouraged the parallel development of what were already quite separate languages; areal features within a Sprachbund. As Watkins (1966) puts it, "the community of -ī in Italic and Celtic is attributable to early contact, rather than to an original unity." The assumed period of language contact could then be later, perhaps continuing well into the first millennium BC.

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