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-European migrations there is little to suggest that it is possible to reconstruct a proto-Indo-Hittite stage that differs substantially from what is already reconstructed for PIE. A shared common ancestor of Indo-European and Uralic, Indo-Uralic, has been postulated as a possible pre-PIE. According to Kortlandt, "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." Anthony states that the validity of such deep relationships cannot be reliably demonstrated due to the time-depth involved, and