Indo-European is a branch of Indo-Uralic which was radically transformed under the influence of a North Caucasian substratum when its speakers moved from the area north of the Caspian Sea to the area north of the Black Sea (cf. Kortlandt 2007b). As a result, Indo-European developed a minimal vowel system combined with a very large consonant inventory including glottalized stops, also grammatical gender and adjectival agreement, an ergative construction which was lost again but has left its traces in the grammatical system, especially in the nominal inflection, a construction with a dative subject which was partly preserved in the historical languages and is reflected in the verbal morphology and syntax, where it gave rise to new categories,...