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 have undergone a change in meaning as well. Today, Indo-European languages are spoken by almost 3 billion native speakers across all inhabited continents, the largest number by far for any recognised language family. Of the 20 languages with the largest numbers of native speakers according to "Ethnologue", 10 are Indo-European: Spanish, English, Hindustani, Portuguese, Bengali, Russian, Punjabi, German, French and Marathi, accounting for over 1.7 billion native speakers. Additionally, hundreds of millions of persons worldwide study Indo-European languages as secondary or tertiary languages, including in cultures which have completely different language families and historical backgrounds—there between 600,000,000 and one billion