Proto-Indo-European language

Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. No direct record of Proto-Indo-European has been discovered; its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. Far more work has gone into reconstructing PIE than any other proto-language. The majority of linguistic work during the 19th century was devoted to the reconstruction of PIE and its daughter languages, and many of the modern techniques of linguistic reconstruction (such as the comparative method) were developed as a result. PIE is hypothesized to have been spoken as a single language from approximately 4500 BCE to 2500 BCE during the Late Neolithic to Early Bronze Age, though other estimates place the bounds of the period as much as more than a thousand years later. According to the prevailing Kurgan hypothesis, the original homeland of the Proto-Indo-Europeans may have been in the Pontic–Caspian steppe of eastern Europe and central Asia. The linguistic reconstruction of PIE has provided insight into the pastoral culture and patriarchal religion of its speakers. As speakers of Proto-Indo-European became isolated from each other through the Indo-European migrations, the regional dialects of Proto-Indo-European spoken by the various groups diverged, as each dialect underwent shifts in pronunciation, morphology, and vocabulary. Over many centuries, these dialects transformed into the known ancient Indo-European languages. From there, more linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages. PIE is believed to have had an elaborate system of morphology that included inflectional suffixes (analogous to English child, child's, children, children's) as well as ablaut (vowel alterations, as preserved in English sing, sang, sung, song) and accent. PIE nominals and pronouns had a complex system of declension, and verbs similarly had a complex system of conjugation. The PIE phonology, particles, numerals, and copula are also well-reconstructed. Asterisks are used by linguists as a conventional mark of reconstructed words, such as *wódr̥, *ḱwn̥tós, or *tréyes; these forms are the reconstructed ancestors of the modern English words water, hound, and three, respectively.