Indo European Languages Essay Help
Indo-European Language Family
By Irene Thompson | Updated February 27, 2017 by Irene Thompson
Indo-European is a family of languages that first spread throughout Europe and many parts of South Asia, and later to every corner of the globe as a result of colonization. The term Indo-European is essentially geographical since it refers to the easternmost extension of the family from the Indian subcontinent to its westernmost reach in Europe. The family includes most of the languages of Europe, as well as many languages of Southwest, Central and South Asia. With over 2.6 billion speakers (or 45% of the world’s population), the Indo-European language family has the largest number of speakers of all language families as well as the widest dispersion around the world.
The cradle of the Indo-Europeans may never be known but an ongoing scholarly debate about the original homeland of Proto-Indo-European (PIE), may some day shed light on the ancestors of all Indo-European languages as well as the people who spoken it. There are two schools of thought:
- Some scholars (e.g., Marija Gimbutas) propose that PIE originated in the steppes north of the Blackand Caspian Seas (the Kurgan hypothesis). Kurgan is the Russian word of Turkic origin for a type of burial mound over a burial chamber. The Kurgan hypothesis combines archaeology with linguistics to trace the diffusion of kurgans from the steppes into southeastern Europe, providing support for the existence ot a Kurgan culture that reflected an early presence of Indo-European people in the steppes and southeastern Europe from the 5th to the 3rd millenium BC.
- Other scholars (e.g., Gamkrelidze and Ivanov) suggest that PIE originated around 7,000 BC in Anatolia, a stretch of land that lies between the Blackand Mediterranean seas. It lies across the Aegean Sea to the east of Greece and is thus usually known by its Greek name Anatolia (Asia Minor). Today, Anatolia is the Asian part of modern Turkey.
It would not have been possible to establish the existence of the Indo-European language family if scholars had not compared the systematically recurring resemblances among European languages and Sanskrit, the oldest language of the Indian subcontinent that left many written documents. The common origin of European languages and Sanskrit was first proposed by Sir William Jones(1746-1794). Systematic comparisons between these languages by Franz Bopp supported this theory and laid the foundation for postulating that all Indo-European languages descended from a common ancestor, Proto-Indo-European (PIE), thought to have been spoken before 3,000 B.C. It then split into different branches which, in turn, split into different languages in the subsequent millennia.
Since PIE left no written records, historical linguists construct family trees, an idea pioneered by August Schleicher, on the basis of the comparative method. The comparative method takes shared features among languages and uses procedures to establish their common ancestry. It is not the only method available but is one that has been most widely used. The examples below show how this method actually works with some Indo-European languages.
|PIE *dekm >||Proto-Germanic *texun > Old English teon > Modern English ten|
Proto-Italic *dekem > Latin decem > Modern Italian dieci
Old Church Slavonic desenti > Modern Bulgarian deset
Sanskrit dáça > Hindi/Urdu das
- proto means ‘old’ in Greek
- * means the form was reconstructed, not attested.
- > means ‘became’
Indo-European languages are classified into 11 major groups, 2 of which are extinct, comprising 449 languages (Ethnologue).
This conservative group has preserved many archaic features thought to have been present in PIE. Some scholars think that Baltic languages share a common ancestral language with the Slavic languages. This hypothetical language is called Balto-Slavic.
Number of speakers
Where spoken primarily
Celtic languages were largely unknown until the modern period. They were once spread over Europe in the pre-Christian era. The oldest records of these languages date back to the 4th century AD.
Number of speakers
Where spoken primarily
|Portuguese||178 million||Portugal, Brazil|
|Spanish||322 million||Spain, Latin America|
Number of speakers
Where spoken primarily
|Czech||11.5 million||Czech Republic|
|Sorbian||70,000 to 110,000||Germany|
Number of speakers
Where spoken primarily
|Russian||150 million L1 speakers||Russia|
Number of speakers
Where spoken primarily
|Bosnian||4 million||Bosnia & Hercegovina|
Number of speakers
Where spoken primarily
|Bengali||100 million 1st language; 211 million 1st & 2nd language speakers||Bangladesh|
|Romani||1.5 million||Romania & elsewhere|
|Sanskrit||194,000 2nd language speakers||India & elsewhere|
|Sinhalese||13.2 million||Sri Lanka|
Number of speakers
Where spoken primarily
|Farsi (Persian)||24.3 million||Iran|
|Kurdish||11 million||Iraq & elsewhere|
|Pashto||19 million||Afghanistan & elsewhere|
Number of speakers
Where spoken primarily
Greek is the only surviving language of this group.
Attested by texts dating to 500-1000 AD that were found in early 20th century in Chinese Turkestan
Unknown until the 20th century when it was discovered during excavations in Turkey. Texts written in cuneiform date to 13th-7th centuries BC.
In addition to these main groups, there are fragmentary records of other Indo-European languages. These records, mostly in the form of inscriptions, do not provide sufficient material for the reconstruction of PIE.
There have been numerous attempts to reconstruct the vowels and consonants of PIE, all of which encountered serious problems due to the uneven nature of the written records and to the huge differences in the age of the records. As a result, the reconstruction of PIE phonology continues to be a matter of scholarly debate and speculation. Among the most notable reconstructions are those by August Schleicher, Karl Brugmann, Winfred Lehmann, Oswald Szemerènyi, and Jacob Grimm.
First Germanic Sound Shift (Grimm’s Law)
You probably know of Jacob Grimm as the author of fairy tales. But he was also one of the great linguists of the 19th century. He found evidence for the unity of all the modern Germanic languages in the phenomenon known as the First Germanic Sound Shift (also known as Grimm’s law ), which set the Germanic branch apart from the other branches of the Indo-European family. This shift occurred before the 7th century when records started to be kept. According to Grimm’s law, the shift occurred when /p, t, k/ in the classical Indo-European languages (Latin, Greek, and Sanskrit) became /f, t, h/ in Germanic languages. For example, Latin pater > Englishfather, Latin cornu > English horn.
You can easily see the resemblances among four common words across five Indo-European languages.
Click here for an amusing illustration of Grimm’s Law and of words for family, plants, animals, sky, and counting in nine Indo-European languages.
The Centum-Satem division explains the evolution of PIE labiovelar, velars, and palatovelar consonants.
- Labiovelar consonants include [kw, gw, xw, ngw] which are pronounced like [k, g, x, ng] but with rounded lips.
- Velars are consonants articulated with the back part of the tongue (the dorsum) against the soft palate (the back part of the roof of the mouth, known also as the velum). They include [k, g, x, ng].
- Palatovelar consonants are articulated with the back part of the tongue against the hard palate. They include [k’, g’, x’, ng’]. For example, [k’] is pronounced as the k in keen.
The terms centum-satem come from the words for ‘one hundred’ in representative languages of each group. Please note that not all languages fall neatly into these categories.
- Satem languages include Baltic, Slavic, Albanian, Armenian, and Indo-Iranian languages. For example, Sanskritsatam, Lithuaniansimtas, Russiansto.
Click here to see the complete satem language tree.
- Centum languages include Romance, Celtic, Germanic, and Greek. For example, Latincentum, Irishcead, Englishhundred, Greek.
Click here to see the complete Centum language tree.
It is believed that PIE had a pitch accent system. All words had only one accented syllable which received a high pitch. Stress could fall on any syllable of a word.
Unevenness of existing records and huge gaps in the chronology among Indo-European languages make the reconstruction of PIE grammar a difficult task. Discoveries of Hittite, Tocharian and Mycenaean Greek in the 20th century have made changes in the data base on which the reconstruction of PIE is based that in turn have modified existing views of PIE. .
Many of the older well-documented languages, such as Sanskrit, Greek, and Latin, have rich morphologies with clearly marked gender and number, as well as elaborately marked case systems for nouns, pronouns, and adjectives. Verbs in these languages also have elaborately marked systems of tense, aspect, mood, and voice, in addition to person, number, and gender. Reconstructed PIE is based on the assumption that it contained all the features found in attested languages. If a given language lacks a particular feature, it is assumed that the feature was lost or that it had merged with other features.
Modern Indo-European languages reflect the rich morphology of PIE to various degrees. For instance, Sanskrit, Greek, Latin, Baltic, Slavic, Celtic, Armenian have extremely rich morphologies. On the other hand, Germanic, Romance, Albanian, and Tocharian do not possess quite as many finely differentiated morphological features.
Nouns, pronouns and adjectives
Sanskrit had the most cases (8), followed by Old Church Slavonic, Lithuanian, and Old Armenian (7), Latin (6), Greek, Old Irish, Albanian (5), Germanic (5).
The three genders (masculine, feminine, neuter) have survived in a number of Indo-European languages.
The three numbers (singular, dual, plural) survived in Sanskrit, Greek, and Old Irish. Vestiges of the dual number can be found in many other Indo-European languages.
- Adjective-Noun agreement
Adjective-noun agreement has survived in many Indo-European languages.
Reconstructed PIE verbs had different sets of endings tense/aspect, voice and mood in addition to person and number. :
- Tense and aspect
It is thought that the PIE verb system was aspect-based, although traditionally, aspect has been confused with tense. Although tense was not formally marked in PIE, most Indo-European languages define their verbal systems in terms of tense, rather than aspect. .
PIE had two voices: active (e.g., The child broke the glass) and medio-passive which combined reflexive and passive voices (e.g., The child washed himself and The child was washed by his mother). In addition to the active voice, various Indo-European languages use the middle or the passive voices.
It is hypothesized the PIE had four moods: indicative, optative, subjunctive, and imperative. Most of these moods exist in all Indo-European languages.
- Person and number
PIE verbs were marked for person (1st, 2nd, 3rd) and number (singular, dual, plural).
Less is know about the syntax of PIE than about its morphology. What is known about PIE word order, therefore, is a subject of conjecture and debate. It is thought likely that word order in PIE sentences was Subject-Object-Verb. This word order is found in Latin, Hittite, Vedic Sanskrit, Tocharian, and to some extent in Greek.
The comparative method enables linguists to reconstruct a basic PIE vocabulary referring to many common elements of their culture. This basic vocabulary is not uniformly attested across all Indo-European languages which suggests that some words may have developed later or were borrowed from other languages. Among words that are reliably reconstructed are words for day, night, the seasons, celestial bodies (sun, moon, stars), precipitation (rain, snow), animals (sheep, horse, pig, bear, dog, wolf, eagle), kinship terms (father, mother, brother, sister, son, daughter), tools (axe, yoke, arrow).
Click here to explore cognates in different Indo-European languages
Written records for various Indo-European languages have different date lines. The table below shows when the first written records appeared, what writing system was used, and which writing systems are used by the languages today.
Earliest written records
Earliest writing system
Current writing system(s)
|Armenian||500 AD||Armenian alphabet||Armenian alphabet|
|Albanian||15th century AD||Greek alphabet||Modified Latin alphabet|
|Greek||1,400 BC||Linear B||Greek alphabet|
|Celtic||4th century AD||Ogham alphabet||Modified Latin alphabet|
|Baltic||16 th century AD||Modified Latin alphabet||Modified Latin alphabet|
|Romance||6th century BC||Latin alphabet, adapted from Etruscan||Modified Latin alphabet|
|Germanic||3rd century AD||runic Futhark||Modified Latin alphabet|
|Slavic||9th century AD||Old Church Slavonic alphabet||Cyrillic and Latin alphabets|
|Indo-Aryan||3rd century BC||Brāhmī script||Bengali, Devanāgarī, Gujarati, Oriya, Gurmukhi, Sinhala, Kaithi,modified Perso-Arabic|
|Iranian||9th century AD||Perso-Arabic script||Modified Perso-Arabic, Arabic, modified Cyrillic, modified Latin.|
|Tocharian||500-1,000 AD||Brāhmī script|
Indo European Languages range from Category I to Category II in terms of difficulty for speakers of English.
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This article is about the family of languages found in much of Europe and Asia. For other uses, see Indo-European.
The Indo-European languages are a language family of several hundred related languages and dialects.
There are about 445 living Indo-European languages, according to the estimate by Ethnologue, with over two thirds (313) of them belonging to the Indo-Iranian branch. The most widely spoken Indo-European languages by native speakers are Spanish, English, Hindustani (Hindi-Urdu), Portuguese, Bengali, Punjabi, Russian, each with over 100 million speakers, with German, French, Italian, and Persian also having significant numbers. Today, about 46% of the human population speaks an Indo-European language as a first language, by far the highest of any language family.
The Indo-European family includes most of the modern languages of Europe; exceptions include Hungarian, Finnish, Estonian, several minor Uralic languages, Turkish (a Turkic language), Basque (a language isolate), and Maltese (a Semitic language). The Indo-European family is also represented in Asia with the exception of East and Southeast Asia. It was predominant in ancient Anatolia (present-day Turkey), the ancient Tarim Basin (present-day Northwest China) and most of Central Asia until the medieval Turkic and Mongol invasions. With written 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-European people can also be reconstructed from the related cultures of ancient and modern Indo-European speakers who continue to live in areas to where the Proto-Indo-Europeans migrated from their original homeland. Several disputed proposals link Indo-European to other major language families.
History of Indo-European linguistics
Main article: Indo-European studies
Although ancient Greek and Roman grammarians noticed similarities between their languages, as well as with surrounding Celtic and Germanic speakers, the sheer ubiquity of Indo-European languages around them led them to the assumption that all human languages were related. This assumption would continue among many grammarians into the early 19th century, the grammatical similarities among Indo-European languages sometimes being seen as evidence of the Tower of Babel until the establishment of the study of Indo-European linguistics proper and the study of non-Indo-European language families.[not in citation given][non-primary source needed]
In the 16th century, European visitors to the Indian subcontinent began to notice similarities among Indo-Aryan, Iranian, and European languages. In 1583, English Jesuit missionary and Konkani scholar Thomas Stephens wrote a letter from Goa to his brother (not published until the 20th century) in which he noted similarities between Indian languages and Greek and Latin.
Another account was made by Filippo Sassetti, a merchant born in Florence in 1540, who travelled to the Indian subcontinent. Writing in 1585, he noted some word similarities between Sanskrit and Italian (these included devaḥ/dio "God", sarpaḥ/serpe "serpent", sapta/sette "seven", aṣṭa/otto "eight", and nava/nove "nine"). However, neither Stephens' nor Sassetti's observations led to further scholarly inquiry.
In 1647, Dutch linguist and scholar Marcus Zuerius van Boxhorn noted the similarity among certain Asian and European languages and theorized that they were derived from a primitive common language which he called Scythian. He included in his hypothesis Dutch, Albanian, Greek, Latin, Persian, and German, later adding Slavic, Celtic, and Baltic languages. However, Van Boxhorn's suggestions did not become widely known and did not stimulate further research.
Ottoman Turkish traveler Evliya Çelebi visited Vienna in 1665–1666 as part of a diplomatic mission and noted a few similarities between words in German and in Persian. Gaston Coeurdoux and others made observations of the same type. Coeurdoux made a thorough comparison of Sanskrit, Latin and Greek conjugations in the late 1760s to suggest a relationship among them. Meanwhile, Mikhail Lomonosov compared different language groups, including Slavic, Baltic ("Kurlandic"), Iranian ("Medic"), Finnish, Chinese, "Hottentot", and others, noting that related languages (including Latin, Greek, German and Russian) must have separated in antiquity from common ancestors.
The hypothesis reappeared in 1786 when Sir William Jones first lectured on the striking similarities among three of the oldest languages known in his time: Latin, Greek, and Sanskrit, to which he tentatively added Gothic, Celtic, and Persian, though his classification contained some inaccuracies and omissions.
Thomas Young first used the term Indo-European in 1813, deriving from the geographical extremes of the language family: from Western Europe to North India. A synonym is Indo-Germanic (Idg. or IdG.), specifying the family's southeasternmost and northwesternmost branches. This first appeared in French (indo-germanique) in 1810 in the work of Conrad Malte-Brun; in most languages this term is now dated or less common than Indo-European, although in German indogermanisch remains the standard scientific term. A number of other synonymous terms have also been used.
Franz Bopp wrote in 1816 On the conjugational system of the Sanskrit language compared with that of Greek, Latin, Persian and Germanic and between 1833 and 1852 he wrote Comparative Grammar. This marks the beginning of Indo-European studies as an academic discipline. The classical phase of Indo-European comparative linguistics leads from this work to August Schleicher's 1861 Compendium and up to Karl Brugmann's Grundriss, published in the 1880s. Brugmann's neogrammarian reevaluation of the field and Ferdinand de Saussure's development of the laryngeal theory may be considered[by whom?] the beginning of "modern" Indo-European studies. The generation of Indo-Europeanists active in the last third of the 20th century (such as Calvert Watkins, Jochem Schindler, and Helmut Rix) developed a better understanding of morphology and of ablaut in the wake of Kuryłowicz's 1956 Apophony in Indo-European, who in 1927 pointed out the existence of the Hittite consonant ḫ. Kuryłowicz's discovery supported Ferdinand de Saussure's 1879 proposal of the existence of coefficients sonantiques, elements de Saussure reconstructed to account for vowel length alternations in Indo-European languages. This led to the so-called laryngeal theory, a major step forward in Indo-European linguistics and a confirmation of de Saussure's theory.
See also: Indo-European migrations and List of languages by first written accounts
The various subgroups of the Indo-European language family include ten major branches, listed below in alphabetical order
- Albanian, attested from the 13th century AD;Proto-Albanian has evolved from an ancient Paleo-Balkan language, traditionally thought to be Illyrian, however, the evidence supporting this is still insufficient.
- Anatolian, extinct by Late Antiquity, spoken in Asia Minor, attested in isolated terms in Luwian/Hittite mentioned in SemiticOld Assyrian texts from the 20th and 19th centuries BC, Hittite texts from about 1650 BC.
- Armenian, attested from the early 5th century AD.
- Balto-Slavic, believed by most Indo-Europeanists to form a phylogenetic unit, while a minority ascribes similarities to prolonged language-contact.
- Slavic (from Proto-Slavic), attested from the 9th century AD (possibly earlier), earliest texts in Old Church Slavonic. Slavic languages include Bulgarian, Russian, Polish, Czech, Slovak, Montenegrin, Macedonian, Bosnian, Croatian, Serbian, Slovenian, Ukrainian, Belarusian, and Rusyn.
- Baltic, attested from the 14th century AD; for languages first attested that recently, they retain unusually many archaic features attributed to Proto-Indo-European (PIE). Living examples are Lithuanian and Latvian.
- Celtic (from Proto-Celtic), attested since the 6th century BC; Lepontic inscriptions date as early as the 6th century BC; Celtiberian from the 2nd century BC; Primitive IrishOgham inscriptions from the 4th or 5th century AD, earliest inscriptions in Old Welsh from the 7th century AD. Modern Celtic languages include Welsh, Cornish, Breton, Scots Gaelic, Irish Gaelic and Manx.
- Germanic (from Proto-Germanic), earliest attestations in runic inscriptions from around the 2nd century AD, earliest coherent texts in Gothic, 4th century AD. Old English manuscript tradition from about the 8th century AD. Includes English, Frisian, German, Dutch, Danish, Swedish, Norwegian, Afrikaans, Yiddish, Low German, Icelandic and Faroese.
- Hellenic and Greek (from Proto-Greek, see also History of Greek); fragmentary records in MycenaeanGreek from between 1450 and 1350 BC have been found.Homeric texts date to the 8th century BC.
- Indo-Iranian, attested circa 1400 BC, descended from Proto-Indo-Iranian (dated to the late 3rd millennium BC).
- Indo-Aryan (including Dardic), attested from around 1400 BC in Hittite texts from Asia Minor, showing traces of Indo-Aryan words. Epigraphically from the 3rd century BC in the form of Prakrit (Edicts of Ashoka). The Rigveda is assumed to preserve intact records via oral tradition dating from about the mid-second millennium BC in the form of Vedic Sanskrit. Includes a wide range of modern languages from Northern India, Pakistan and Bangladesh including Hindustani, Bengali, Assamese, Punjabi, Kashmiri, Gujarati, Marathi, Odia and Nepali as well as Sinhalese of Sri Lanka.
- Iranian or Iranic, attested from roughly 1000 BC in the form of Avestan. Epigraphically from 520 BC in the form of Old Persian (Behistun inscription). Includes Persian, Ossetian and Kurdish
- Italic (from Proto-Italic), attested from the 7th century BC. Includes the ancient Osco-Umbrian languages, Faliscan, as well as Latin and its descendants (the Romance languages).
- Tocharian, with proposed links to the Afanasevo culture of Southern Siberia. Extant in two dialects (Turfanian and Kuchean, or Tocharian A and B), attested from roughly the 6th to the 9th century AD. Marginalized by the Old TurkicUyghur Khaganate and probably extinct by the 10th century.
In addition to the classical ten branches listed above, several extinct and little-known languages and language-groups have existed:
- Illyrian: possibly related to Albanian, Messapian, or both
- Venetic: shares several similarities with Latin and the Italic languages, but also has some affinities with other IE languages, especially Germanic and Celtic.
- Liburnian: doubtful affiliation, features shared with Venetic, Illyrian, and Indo-Hittite, significant transition of the Pre-Indo-European elements
- Messapian: not conclusively deciphered
- Phrygian: language of the ancient Phrygians
- Paionian: extinct language once spoken north of Macedon
- Thracian: possibly including Dacian
- Dacian: possibly very close to Thracian
- Ancient Macedonian: proposed relationship to Greek.
- Ligurian – possibly close to or part of Celtic.
- Sicel: an ancient language spoken by the Sicels (Greek Sikeloi, Latin Siculi), one of the three indigenous (i.e. pre-Greek and pre-Punic) tribes of Sicily. Proposed relationship to Latin or proto-Illyrian (Pre-Indo-European) at an earlier stage.
- Lusitanian: possibly related to (or part of) Celtic, Ligurian, or Italic
- Cimmerian: possibly Iranic, Thracian, or Celtic
Further information: Language families
Membership of languages in the Indo-European language family is determined by genealogical relationships, meaning that all members are presumed descendants of a common ancestor, Proto-Indo-European. Membership in the various branches, groups and subgroups of Indo-European is also genealogical, but here the defining factors are shared innovations among various languages, suggesting a common ancestor that split off from other Indo-European groups. For example, what makes the Germanic languages a branch of Indo-European is that much of their structure and phonology can be stated in rules that apply to all of them. Many of their common features are presumed innovations that took place in Proto-Germanic, the source of all the Germanic languages.
Tree versus wave model
See also: Language change
The "tree model" is considered an appropriate representation of the genealogical history of a language family if communities do not remain in contact after their languages have started to diverge. In this case, subgroups defined by shared innovations form a nested pattern. The tree model is not appropriate in cases where languages remain in contact as they diversify; in such cases subgroups may overlap, and the "wave model" is a more accurate representation. Most approaches to Indo-European subgrouping to date have assumed that the tree model is by-and-large valid for Indo-European; however, there is also a long tradition of wave-model approaches.
In addition to genealogical changes, many of the early changes in Indo-European languages can be attributed to language contact. It has been asserted, for example, that many of the more striking features shared by Italic languages (Latin, Oscan, Umbrian, etc.) might well be areal features. More certainly, very similar-looking alterations in the systems of long vowels in the West Germanic languages greatly postdate any possible notion of a proto-language innovation (and cannot readily be regarded as "areal", either, because English and continental West Germanic were not a linguistic area). In a similar vein, there are many similar innovations in Germanic and Balto-Slavic that are far more likely areal features than traceable to a common proto-language, such as the uniform development of a high vowel (*u in the case of Germanic, *i/u in the case of Baltic and Slavic) before the PIE syllabic resonants *ṛ,* ḷ, *ṃ, *ṇ, unique to these two groups among IE languages, which is in agreement with the wave model. The Balkan sprachbund even features areal convergence among members of very different branches.
Using an extension to the Ringe-Warnow model of language evolution, early IE was confirmed to have featured limited contact between distinct lineages, whereas only the Germanic subfamily exhibited a less treelike behaviour as it acquired some characteristics from neighbours early in its evolution rather than from its direct ancestors. The internal diversification of especially West Germanic is cited to have been radically non-treelike.
Specialists have postulated the existence of higher-order subgroups such as Italo-Celtic, Graeco-Armenian, Graeco-Aryan or Graeco-Armeno-Aryan, and Balto-Slavo-Germanic. However, unlike the ten traditional branches, these are all controversial to a greater or lesser degree.
The Italo-Celtic subgroup was at one point uncontroversial, considered by Antoine Meillet to be even better established than Balto-Slavic. The main lines of evidence included the genitive suffix -ī; the superlative suffix -m̥mo; the change of /p/ to /kʷ/ before another /kʷ/ in the same word (as in penkʷe > *kʷenkʷe > Latin quīnque, Old Irish cóic); and the subjunctive morpheme -ā-. This evidence was prominently challenged by Calvert Watkins; while Michael Weiss has argued for the subgroup .
Evidence for a relationship between Greek and Armenian includes the regular change of the second laryngeal to a at the beginnings of words, as well as terms for "woman" and "sheep". Greek and Indo-Iranian share innovations mainly in verbal morphology and patterns of nominal derivation. Relations have also been proposed between Phrygian and Greek, and between Thracian and Armenian. Some fundamental shared features, like the aorist (a verb form denoting action without reference to duration or completion) having the perfect active particle -s fixed to the stem, link this group closer to Anatolian languages and Tocharian. Shared features with Balto-Slavic languages, on the other hand (especially present and preterit formations), might be due to later contacts.
The Indo-Hittite hypothesis proposes that the Indo-European language family consists of two main branches: one represented by the Anatolian languages and another branch encompassing all other Indo-European languages. Features that separate Anatolian from all other branches of Indo-European (such as the gender or the verb system) have been interpreted alternately as archaic debris or as innovations due to prolonged isolation. Points proffered in favour of the Indo-Hittite hypothesis are the (non-universal) Indo-European agricultural terminology in Anatolia and the preservation of laryngeals. However, in general this hypothesis is considered to attribute too much weight to the Anatolian evidence. According to another view, the Anatolian subgroup left the Indo-European parent language comparatively late, approximately at the same time as Indo-Iranian and later than the Greek or Armenian divisions. A third view, especially prevalent in the so-called French school of Indo-European studies, holds that extant similarities in non-satem languages in general—including Anatolian—might be due to their peripheral location in the Indo-European language-area and to early separation, rather than indicating a special ancestral relationship. Hans J. Holm, based on lexical calculations, arrives at a picture roughly replicating the general scholarly opinion and refuting the Indo-Hittite hypothesis.
Satem and centum languages
Main article: Centum and satem languages
The division of the Indo-European languages into satem and centum groups was put forward by Peter von Bradke in 1890, although Karl Brugmann had proposed a similar type of division in 1886. In the satem languages, which include the Balto-Slavic and Indo-Iranian branches, as well as (in most respects) Albanian and Armenian, the reconstructed Proto-Indo-European palatovelars remained distinct and were fricativized, while the labiovelars merged with the "plain velars". In the centum languages, the palatovelars merged with the plain velars, while the labiovelars remained distinct. The results of these alternative developments are exemplified by the words for "hundred" in Avestan (satem) and Latin (centum)—the initial palatovelar developed into a fricative [s] in the former, but became an ordinary velar [k] in the latter.
Rather than being a genealogical separation, the centum–satem division is commonly seen as resulting from innovative changes that spread across PIE dialect-branches over a particular geographical area; the centum–satem isogloss intersects a number of other isoglosses that mark distinctions between features in the early IE branches. It may be that the centum branches in fact reflect the original state of affairs in PIE, and only the satem branches shared a set of innovations, which affected all but the peripheral areas of the PIE dialect continuum. Kortlandt proposes that the ancestors of Balts and Slavs took part in satemization before being drawn later into the western Indo-European sphere.
See also: Origin of language
Some linguists propose that Indo-European languages form part of one of several hypothetical macrofamilies. However, these theories remain highly controversial, not being accepted by most linguists in the field. Some of the smaller proposed macrofamilies include:
Other, greater proposed families including Indo-European languages, include:
Objections to such groupings are not based on any theoretical claim about the likely historical existence or non-existence of such macrofamilies; it is entirely reasonable to suppose that they might have existed. The serious difficulty lies in identifying the details of actual relationships between language families, because it is very hard to find concrete evidence that transcends chance resemblance, or is not equally likely explained as being due to borrowing (including Wanderwörter, which can travel very long distances). Because the signal-to-noise ratio in historical linguistics declines steadily over time, at great enough time-depths it becomes open to reasonable doubt that one can even distinguish between signal and noise.
Main article: Proto-Indo-European language
The proposed Proto-Indo-European language (PIE) is the hypothetical common ancestor of the Indo-European languages, spoken by the Proto-Indo-Europeans. From the 1960s, knowledge of Anatolian became certain enough to establish its relationship to PIE. Using the method of internal reconstruction an earlier stage, called Pre-Proto-Indo-European, has been proposed.
PIE was an inflected language, in which the grammatical relationships between words were signaled through inflectional morphemes (usually endings). The roots of PIE are basic morphemes carrying a lexical meaning. By addition of suffixes, they form stems, and by addition of endings, these form grammatically inflected words (nouns or verbs). The hypothetical Indo-European verb system is complex and, like the noun, exhibits a system of ablaut.
See also: Indo-European migrations
Blue: centum languages
Red: satem languages
Orange: languages with augment
Green: languages with PIE *-tt- > -ss-
Tan: languages with PIE *-tt- > -st-
Pink: languages with instrumental, dative and ablative plural endings (and some others) in *-m- rather than *-bh-