Proto-Indo-European language

Proto-Indo-European (PIE)[1]is the linguistic reconstruction of the hypothetical common ancestor of the Indo-European languages, the most widely spoken language family in the world.

Far more work has gone into reconstructing PIE than any other proto-language, and it is by far the best understood of all proto-languages of its age. The vast majority of linguistic work during the 19th century was devoted to the reconstruction of PIE or its daughter proto-languages (such as Proto-Germanic), and most of the modern techniques of linguistic reconstruction such as the comparative method were developed as a result. These methods supply all current knowledge concerning PIE since there is no written record of the language.

PIE is estimated to have been spoken as a single language from 4500 BC to 2500 BC[2] during the Late Neolithic to Early Bronze Age, though estimates vary by more than a thousand years. 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. The linguistic reconstruction of PIE has also provided insight into the culture and religion of its speakers.[3]

As Proto-Indo-Europeans became isolated from each other through the Indo-European migrations, the Proto-Indo-European language became spoken by the various groups in regional dialects which then underwent the Indo-European sound laws divergence, and along with shifts in morphology, these dialects slowly but eventually transformed into the known ancient Indo-European languages. From there, further linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages. Today, the descendant languages, or daughter languages, of PIE with the most speakers are Spanish, English, Hindustani (Hindi and Urdu), Portuguese, Bengali, Russian, Punjabi, German, Persian, French, Italian and Marathi. Hundreds of other living descendants of PIE range from languages as diverse as Albanian (gjuha shqipe), Kurdish (کوردی‎), Nepali (खस भाषा), Tsakonian (τσακώνικα), Ukrainian (українська мова), and Welsh (Cymraeg).

PIE had an elaborate system of morphology that included inflectional suffixes(analogous to English life, lives, life's, lives'‍) as well as ablaut (vowel alterations, for example, as preserved in English sing, sang, sung) 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.

An asterisk is used to mark reconstructed words, such as *wódr̥ 'water', *ḱwṓ 'dog' (English hound), or *tréyes 'three (masculine)'.

Development of the hypothesis

No direct evidence of PIE remains – scholars have reconstructed PIE from its present-day descendants using the comparative method.[4]

The comparative method follows the Neogrammarian rule: the Indo-European sound laws apply without exception. The method compares languages and uses the sound laws to find a common ancestor. For example, compare the pairs of words in Italian and English: piede and foot, padre and father, pesce and fish. Since there is a consistent correspondence of the initial consonants that emerges far too frequently to be coincidental, one can assume that these languages stem from a common parent-language.[5]

Many consider William Jones, an Anglo-Welsh philologist and puisne judge in Bengal, to have begun Indo-European studies in 1786, when he postulated the common ancestry of Sanskrit, Latin, and Greek.[6] However, he was not the first to make this observation. In the 1500s, European visitors to the Indian subcontinent became aware of similarities between Indo-Iranian languages and European languages,[7] and as early as 1653 Marcus Zuerius van Boxhorn had published a proposal for a proto-language ("Scythian") for the following language families: Germanic, Romance, Greek, Baltic, Slavic, Celtic, and Iranian.[8] In a memoir sent to the Académie des Inscriptions et Belles-Lettres in 1767 Gaston-Laurent Coeurdoux, a French Jesuit who spent all his life in India, had specifically demonstrated the analogy between Sanskrit and European languages.[9] In some ways, Jones' work was less accurate than his predecessors', as he erroneously included Egyptian, Japanese and Chinese in the Indo-European languages, while omitting Hindi.

In 1818 Rasmus Christian Rask elaborated the set of correspondences to include other Indo-European languages, such as Sanskrit and Greek, and the full range of consonants involved. In 1816 Franz Bopp published On the System of Conjugation in Sanskrit in which he investigated a common origin of Sanskrit, Persian, Greek, Latin, and German. In 1833 he began publishing the Comparative Grammar of Sanskrit, Zend, Greek, Latin, Lithuanian, Old Slavic, Gothic, and German.[10]

In 1822 Jacob Grimm formulated what became known as Grimm's law as a general rule in his Deutsche Grammatik. Grimm showed correlations between the Germanic and other Indo-European languages and demonstrated that sound change systematically transforms all words of a language.[11] From the 1870s the Neogrammarians proposed that sound laws have no exceptions, as shown in Verner's law, published in 1876, which resolved apparent exceptions to Grimm's law by exploring the role that accent (stress) had played in language change.[12]

August Schleicher's A Compendium of the Comparative Grammar of the Indo-European, Sanskrit, Greek and Latin Languages (1874–77) represented an early attempt to reconstruct the proto-Indo-European language.[13]

By the early 1900s Indo-Europeanists had developed well-defined descriptions of PIE which scholars still accept today. Later, the discovery of the Anatolian and Tocharian languages added to the corpus of descendant languages. A new principle won wide acceptance in the laryngeal theory, which explained irregularities in the linguistic reconstruction of Proto-Indo-European phonology as the effects of hypothetical sounds which had disappeared from all documented languages, but which were later observed in excavated cuneiform tablets in Anatolian.

Julius Pokorny's Indogermanisches etymologisches Wörterbuch ("Indo-European Etymological Dictionary", 1959) gave a detailed, though conservative, overview of the lexical knowledge then accumulated. Kuryłowicz's 1956 Apophonie gave a better understanding of Indo-European ablaut. From the 1960s, knowledge of Anatolian became robust enough to establish its relationship to PIE.

Classification of Indo-European languages. Red: Extinct languages. White: categories or unattested proto-languages. Left half: centum languages; right half: satem languages
Other Languages
brezhoneg: Indezeuropeg
Gàidhlig: Innd-Eòrpais
Bahasa Indonesia: Bahasa Proto-Indo-Eropa
norsk nynorsk: Urindoeuropeisk
slovenčina: Praindoeurópčina
slovenščina: Indoevropski prajezik
srpskohrvatski / српскохрватски: Indoevropski prajezik
Lingua Franca Nova: Protoindoeuropean