Indo-European copula copula (with corresponding voiceless and voiced fricatives) existed side by side in Germanic, and the involvement of a separate root "" is unnecessary. The root "*(s)teh-" meant "to stand". From this root comes the present stem of the so-called "substantive verb" in Irish and Scottish Gaelic, "tá" and "tha" respectively. On the absence of the initial s- in Celtic, see Indo-European s-mobile. In Latin, "stō, stare" retained the meaning "to stand", until local forms of Vulgar Latin began to use it as a copula in certain circumstances. Today, this survives in that several Romance languages (Galician-Portuguese, Spanish, Catalan) use it
Indo-Hittite common innovations." Hittite, as well as its Anatolian cousins, split off from Proto-Indo-European at an early stage, thereby preserving archaisms that were later lost in the other Indo-European languages. Traditionally there has been a strong notion among Indo-European linguistics that the Anatolian branch was separated earlier than other branches. Within the framework of the Kurgan hypothesis, the split is estimated to have occurred in roughly 4000 BC. Some fundamental shared features, such as the aorist category of the verb (which denotes action without reference to duration or completion), with the perfect active particle -s fixed to the stem, link the