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 languages evidence appearing since the Bronze Age in the form of the Anatolian languages and Mycenaean Greek, the Indo-European family is significant to the field of historical linguistics as possessing the second-longest recorded history, after the Afroasiatic family, although certain language isolates, such as Sumerian, Elamite, Hurrian, Hattian, and Kassite are recorded earlier. All Indo-European languages are descendants of a single prehistoric language, reconstructed as Proto-Indo-European, spoken sometime in the Neolithic era. Although no written records remain, aspects of the culture and religion of the Proto-Indo-Europeans can also be reconstructed from the related cultures of ancient and modern Indo-European speakers who