The ablaut patterns of Proto-Kartvelian are highly similar to those of the Indo-European languages, and so it is widely thought that Proto-Kartvelian interacted with Indo-European at a relatively early date. This is reinforced by a fairly large number of words borrowed from Indo-European, such as the Proto-Kartvelian *mḳerd- (breast), and its possible relation to the Proto-Indo-European *ḱerd- (heart). Proto-Kartvelian *ṭep- (warm) may also be directly derived from Proto-Indo-European *tep- “warm”. It is also asserted that the name of wine in Indo-European languages is borrowed from Proto-Kartvelian *ɣwino, implicating quite close relations between these languages.
The modern descendants of Proto-Kartvelian are Georgian, Svan, Mingrelian and Laz. Of these, Mingrelian and Laz are often considered dialects of a single language, called Zan, although the two are not inherently mutually intelligible. The ablaut patterns of Proto-Kartvelian were better preserved in Georgian and (particularly) Svan than in either Mingrelian or Laz, in which new forms have been set up so that there is a single, stable vowel in each word element.
The system of pronouns of Proto-Kartvelian is distinct on account of its category of inclusive–exclusive (so, for instance, there were two forms of the pronoun "we": one that includes the listener and one that does not). This has survived in Svan but not in the other languages. Svan also includes a number of archaisms from the Proto-Kartvelian era, and therefore it is thought that Svan broke off from Proto-Kartvelian at a relatively early stage: the later Proto-Kartvelian stage (called Karto-Zan) split into Georgian and Zan (Mingrelo-Laz).