ProtoIndoEuropean

Proto-Indo-European (PIE) is the reconstructed ancestor of the Indo-European language family. It is not directly attested; knowledge comes from the comparative method, using cognates across Sanskrit, Greek, Latin, Old Irish, Hittite, and other languages to infer phonology, morphology, and core lexicon.

Phonology and grammar: PIE is reconstructed with stops p t k; b d g; aspirated bh dh gh; and labiovelars such as kʷ. It is notable for the theory of three laryngeals h1, h2, h3, which are posited to have colored adjacent vowels. The vowel system includes ablaut with e, o, and zero grades. Nouns had multiple cases and genders; verbs distinguished aspect and mood with various stems.

Lexicon and descendants: Core PIE vocabulary covers kinship terms, numbers, natural phenomena, and everyday life. Laryngeals and ablaut patterns help explain irregular forms across descendants. Daughter languages include Anatolian and Tocharian, as well as Greek, Indo-Iranian, Italic, Celtic, Germanic, Armenian, and Albanian.

Homeland and dating: The Steppe hypothesis places PIE in the Pontic-Caspian steppe around 4000–2500 BCE; the Anatolian hypothesis ties PIE to early farming in Anatolia. Most linguists favor steppe origins, though debate continues as new evidence from ancient texts emerges.