Peculiarities include syllabic nasals, laterals, and rhotics, even rare long ones, which developed a vowel in all descendants except some Slavonic; and apparently three sounds of unknown quality, called laryngeals, which disappeared in all descendants but changed surrounding vowels as evidence of their existence.

Proto-Indo-European or PIE's wider affinities are unknown, but by some linguists it is linked with Etruscan and/or Afro-Asiatic and/or Finno-Ugrian. (This is the Nostratic theory.)

The grammar resembles that of Sanskrit or Lithuanian more than any other descendant, and for this reason it is sometimes absurdly claimed that a modern Lithuanian could understand Sanskrit. They are, I'm afraid, far too different. But archaic features they share are locative and instrumental cases, a dual number, and tones. Most other IE descendants have lost some or all of these.

For example, with ekwos, the masculine word for "horse", giving rise to the familiar Latin equus and Greek hippos, and to Sanskrit asvah. This is an o-stem, like most masculines, meaning that -o- runs through the declension, between the stem and the ending:

Nominative ekw-o-s
Vocative ekw-e
Accusative ekw-o-m
Genitive ekw-o-syo
Dative ekw-o-ey or ekw-ooy
Ablative ekw-o-od
Locative ekw-o-y
Instrumental ekw-o-o
And in the plural:
Nom./Voc. ekw-o-es
Acc. ekw-o-ns
Gen. ekw-o-om
Dat./Abl. ekw-o-ibhyos
Loc. ekw-o-isu
Inst. ekw-o-oys

The nom., voc., and acc. singular are obvious to anyone who knows a bit of Latin or Greek, but some other cases have travelled a great deal to get to their classical form: e.g. Greek gen. sg. -osyo > -ohyo > -oyo > -oo > -ou.

As Muke discusses below, there was a series of labiovelar consonants including kw, but it is noteworthy that ekwos doesn't contain this. It's a sequence k-w, as shown by the fact that in the satem language Sanskrit the k shifts to a sibilant, and the w separately changes to v.

It's unknown where the case endings came from originally. If they were just postpositions (as in Japanese ga and o and ni), why are the plural endings not recognisably formed from the same singular marker plus a plural element (as in an agglutinative language like Turkish)? These fused or analytic case markings are rare outside IE.

It's also unknown how the gender system came about, because although males belong to masculine and females belong to feminine, all other words are scattered unpredicyably through masculine, feminine, and neuter in the way that makes such a pain for people studyng most modern European languages. One idea is that the -om of the neuter is originally the accusative ending, because neuter things don't usually actively do anything (see animacy hierarchy) so don't need a subject ending.

Proto-Indo-European is a language hypothesized to be the ancestor of most of the languages of Europe and quite a few languages of Asia. These descendants are called Indo-European languages (or Indogermanic or Aryan in some sources).

PIE itself would have been spoken several thousand years ago--at least two thousand years before the invention of writing--so we can have no written records of it. What we know of its words has been reconstructed using the comparative method, which means searching for correspondences in the daughter languages and hypothesizing regular changes to account for them. For example, we can say that English "brother" and Greek "phrater" are related, as English b and Greek ph regularly correspond to PIE *bh, and th and t to IE *t. (The full root is *bhreH2-ter-.)


PIE has usually been reconstructed as having five series of stops:

      Labial: p  b  bh
      Dental: t  d  dh
     Palatal: k' g' gh'
       Velar: k  g  gh
  Labiovelar: kw gw ghw

The first column are voiceless, the second voiced, the third voiced aspirated, although these were most likely not their actual values. For example, PIE *b is rare, and it's not common in existing languages to have voiced aspirates without also having voiceless aspirates. The Glottalic Hypothesis reinterprets the second column as "glottalized" voiceless (ejectives) and the third column as voiced. This fits the reconstruction better, as it is common for languages with ejectives to not have a labial ejective. An alternate theory is that *b had already merged with *w in pre-PIE times, and IIRC this hypothesis is supported by several *w-initial homophonous roots (but I'm not sure of this offhand).

The generic root structure of Proto-Indo-European was CVC, where the vowel is usually *e, but can ablaut to *o or to zero (nothing). A regular PIE root cannot have two consonants from the second column, and it cannot have both one from the first column and one from the third column.

The only fricative in PIE is *s. There are two nasals, *m and *n; two liquids, *r and *l; and two glides, *y and *w. The laryngeals may have been fricatives, though, and are occasionally so reconstructed.

PIE had very few vowels. For certain, there is *e. There are also *i and *u, which are syllabic versions of *y and *w. *o interchanges with *e by ablaut. *a and *o also can appear as *e is colored by a laryngeal. The laryngeals are sounds that disappeared from PIE and only appear historically in Anatolian languages like Hittite. Their effect was to "color" the preceding or following *e to another vowel, and to lengthen a preceding vowel. *H1 was "uncolored", *H2 was "a-colored", and *H3 was "o-colored".

If that's difficult, an example: later PIE *do:- would represent an earlier PIE *deH3- and a later PIE *an- would probably represent earlier PIE *H2an-.

Besides laryngeals, the palatals were also lost in many languages. Rather, the palatals in many languages (the "centum" languages) merged with the velars. In other languages (the "satem" languages) the palatals remained distinct from the velars, usually becoming sibilants. The terms centum and satem come from the Latin and Sanskrit words for "a hundred" and are examples of the division. An alternate theory is that the "plain" velar *k *g *gh series didn't exist; the number of *k/*g/*gh-containing roots is thought to be overestimated because this is the "default" bin they are put into when comparative evidence can't place them firmly in the conventional palatal or labiovelar series. Under this theory satem languages shifted the conventional palatals to sibilants, and the centum ones kept them as velar stops.



PIE nouns decline for case and number. There are different endings depending on the ending of the root/stem. The cases generally reconstructed are nominative, vocative, accusative, instrumental, dative, genitive, ablative, and locative.

The following table is appropriated from New Comparative Grammar of Greek and Latin by Andrew Sihler. An equals sign follows a syllabic resonant, and 0 indicates an absence of an ending. (neut) indicates the nominative and accusative of neuter nouns, which are identical. eH2-stems are more commonly recognized as a:-stems.

     Cons-stem  o-stem  eH2-stem    i-stem  u-stem
Nom  -s/-0      -o-s    -eH2-0      -i-s    -u-s
Voc  -0         -e-0    -eH2-0      -ey-0   -ew-0
Acc  -m=        -o-m    -eH2-m      -i-m    -u-m
(neut) -0       -o-m      N/A       -i-0    -u-0
Ins  -bhi,      -o-H1,  -eH2-bhi,   -i-bhi  -u-bhi
     -mi,       -e-H1   -eH2-eH1 ?  -i-H1   -u-H1
Dat  -ey        -o:y    -eH2-ey     -ey-ey  -ew-ey
Gen  -s,        -i:,    -eH2-es,    -oy-s   -ow-s
     -os,       -osyo   -eH2-os
     -e s
Abl  = Gen      -o:t,   = Gen       = Gen   = Gen
Loc  -i/-0      -o-y    -eH2-i      -e:y-0  -e:w-0

        Cons-stem  o-stem   eH2-stem    i-stem    u-stem
Nom/Voc -es        -o:s     -eH2-es     -ey-es    -ew-es
(pron.)            -oy
Acc     -m=s       -o-ms    -eH2-ms     -i-ms     -u-ms
neut.   -H2        -eH2      N/A        -i-H2     -u-H2
Ins     -bhis,     -o:ys,   -eH2-bhis,  -i-bhis,  -u-bhis,
        -mis,      -o-mis,? -eH2-mis,   -i-mis,   -u-mis,
        -mi:s      -o-mi:s? -eH2-mi:s,  -i-mi:s,  -u-mi:s
Gen     -om ?      -o:m     -eH2-om     -y-om     -w-om
(pron.)            -oyso:m  -eH2so:m
Dat/Abl -bhos,     -o-bhos, -eH2-bhos,  -i-bhos,  -u-bhos,
        -mos,      -o-mos   -eH2-mos,   -i-mos    -u-mos
Loc     -su        (-o-su)? -eH2-su     -i-su     -u-su
(pron.)            -oysu

There was a dual, which is weak even in PIE and doesn't survive in many IE languages, and reconstructing the endings appears to be problematic, the most secure appears to be the m./f. dual nom./acc./voc., being *-H1 (although it might have been *-H1e, or *-e, or even *-H3 apparently).

Ablaut also appears, especially in root nouns. The details of this are complicated and will appear later...


...verbs are also complicated. I will put up more later, but till then here are the personal endings for active verbs as reconstructed (source same as above)

Secondary Endings
      sg      du     pl
1st  -m/-m=  -we(:) -me(:)
2nd  -s      -tom   -te
3rd  -t      -ta:m  -nt/-n=t/-r=/-e:r

Primary Endings
      sg        du     pl
1st  -oH2/-mi  -wos   -mos
2nd  -si       -tH1es -te
3rd  -ti/-i    -tes   -nti/-n=ti


PIE gave birth to the following families:

Extinct languages such as Hittite and Luvian.
Languages of Eastern Europe, such as Russian, Lithuanian, Latvian, Polish, and Czech. Lithuanian became famous in PIE for how well it preserved the ancient word endings.
Languages of Western Europe, such as Welsh, Irish Gaelic, and Scots Gaelic. Two major branches of Celtic are Goidelic and Brittonic, called "q-Celtic" and "p-Celtic" respectively, based on their separate reflexes of PIE *kw.
Languages of Northern and Western Europe, such as German, Afrikaans, English, Swedish, and Yiddish.
Basically just Greek, which has history all the way back to Linear B...
Latin and all its descendants (Spanish, Romanian, French...) as well as extinct languages like Oscan and Faliscan.
Also "Indo-Aryan". Most of the Asian PIE languages: Avestan, Persian, Sanskrit and its descendants (Hindi, Bengali, Romany...)
According to myth the forbidden experiment once determined this was the original language of mankind...
Once spoken in what is now a part of China, its languages are imaginatively titled Tocharian A and Tocharian B.

The Italic and Celtic families are generally thought to be closer to each other (or even Italo-Celtic), and similarly with Balto-Slavic and Germanic.

There are theories that Proto-Indo-European is related to other language families. Some proposals, like Nostratic, try to continue the comparative method, but it is not universally agreed that the comparative method can give accurate results with the span of time involved. Others, such as Greenberg's Eurasiatic, use different methods that are not as widely approved.

Whew, glad that's over...

Based on their recreation of the grammar and vocabulary of Proto-Indo-European, some linguists have written short passages in the language, which provide an interesting glimpse into the way our linguistic ancestors were speaking thousands of years ago. These passages are, by necessity, rather simple, given that much of our knowledge of PIE is speculative, and the fact that it was never actually written by its native speakers.

S. K. Sen has translated an extract from Old Indic literature (an IE language) into Proto-Indo-European. Its English meaning is this:

Once there was a king. He was childless. The king wanted a son. He asked his priest, "May a son be born to me!" The priest said to the king, "Pray to the god Varuna."

The king approached the god Varuna to pray now to the god. "Hear me, father Varuna!" The god Varuna came down from heaven. "What do you want?"

"I want a son."

"Let this be so," said the bright god Varuna. The king's lady bore a son.

Following is Sen's translation, written in a simplified form from that used by linguists. There are two points to bear in mind. First, PIE did not use definite or indefinite articles, so "a king" is just "king". Second, the verb usually comes at the end of the clause, so "he asked his priest" is "he his priest asked".
To réecs éhest. So nnputlos éhest. So réecs súhnum éwelt. Só tóso gceutérmm prrcset, "Súhnus moi ccnnhyotaam!" So gceutéer tom réeccmm éweuqet, "Ihkkeswo tteiwóm Wérunom."

So réecs tteiwóm Werunom húpo-sesore nu tteiwóm ihkketo. Cludí moi, phhter Werune!" Tteiwós Wérunos kmmta ttiwós éqqeht. "Qítt welsi?"

"Wélmi súhnum."

"Tótt héstu," wéuqet loukós tteiwos Werunos." Reeccós pótnih súhnum kkekkonhe."

Though is immediately obvious that this language is very different from English and totally incomprehensible to anyone but linguists, there are nonetheless some words and roots which survive, in altered form, in modern Indo-European languages. Réecs, for "king", is obviously the ancestor of the Latin rex, from which derives the French roi and thus the basis of the English "royal". Similarly, phhter is like its English translation, "father", while moi, for "me", is identical in spelling to the modern French, and súhnum is obviously the ancestor of our own word "son".

A slightly longer passage was written in the 19th century by August Schleicher. Instead of adapting a known early Indo-European text to Proto-Indo-European, he wrote a fable of his own, called "The Sheep and the Horses". Our knowledge of PIE has moved on since Schleicher's time, and the passage is now usually written in updated form. One such version is given in Jared Diamond's The Rise and Fall of the Third Chimpanzee; the original update came from W.P. Lehmann and L. Zgusta in 1979, and Diamond himself adapts the text for the benefit of non-linguists, with advice from Jaan Puhvel.

In English the fable reads like this:

On a hill, a sheep that had no wool saw horses, one of them pulling a heavy wagon, one carrying a big load, and one carrying a man quickly.

The sheep said to the horses, "My heart pains me, seeing a man driving horses."

The horses said, "Listen, sheep, our hearts pain us when we see this: a man, the master, makes the wool of the sheep into a warm garment for himself. And the sheep has no wool.

Having heard this, the sheep fled into the plain.

And this is the Proto-Indo-European translation, entitled "Owis Ekwoosque":
Gwrreei, quesyo wlhnaa ne eest, ekwoons espeket, oinom ghe gwrrum woghom weghontm, oinomque megam bhorom, oinomque ghmmenm ooku bherontm.

Odwis nu ekwomos ewewquet, "Keer aghnutoi moi ekwoons agontm nerm widntei."

Ekwoos tu ewewquont, "Kludhi, owei, keer ghe aghnutoi nsmei widntmos: neer, potis, owioom r wlhnaam sebhi gwhermom westrom qurnneuti. Neghi owioom wlhnaa esti."

Tod kekluwoos owis agrom ebhuget.

Once again, the passage looks like Martian (even without the proliferation of diacritical marks found in the first passage) but proves on closer inspection to contain many recognisable roots. Owis, for "sheep", is related to the Latin ovis and the English word "ewe". Wlhnaa is the root of our "wool", keer, for "heart", is an ancestor of the French coeur, and ekwoos, for "horses", is the root of (now extinct) words in many Romance languages as well as horse-related words in English such as "equestrian".
Reference: See for an alternate version of the second story.

Proto-Indo-European is the hypothetical mother-tongue of all the Indo-European languages. The vocabulary of PIE allows anthropologists to make a pretty educated guess as to the homeland of the Indo-Europeans somewhere in Southwest Asia, perhaps on the steppes of the Volga. Being a very expansive culture, the archaeological record traces the movements of these people with such typically Indo-European things as horses, wheel vehicles, double-headed axes, pastoral economy, and patricarchal society. The lexicon of the reconstructed PIE shows a lot about culture, economy, religion, etc. Here are a few common PIE roots, with examples in later languages.

Since my main source for this write-up is Lyle Campbell's Historical Linguistics, ©1998, I will use his classifications, which are very good, in my opinion. The following are not in IPA, but there are guides to pronunciation. A consonant followed by 'h' indicates aspiration, 'ë' indicates a schwa, an acute accent mark indicates length, 'j' will indicate palatization, 'w' will indicate labialization, an underline will indicate voicelessness, 'j' also represents the 'y' sound of English, 'x' will be used to represent the 'laryngeals' when they occur. The '*' indicates a supposed proto-form. Here're the words:

Social Structure: PIE Society was patriarchal, patrilineal (descent through the father), and patrilocal (brides moved in with the husband's family). Societies were stratified, with a tribal king, noble and warrior class, and a peasant and farmer class.

  • *demë- 'house, household' (Greek(Gk.) despotés 'master', 'lord'... *dems-pot- 'house-master' (*-pot- 'powerful'), Latin(Lt.) dominus 'master of a household'... *dom-o-no)
  • *dá-mo 'division of society, community division by location' (Gr. démos 'people, land'; the source of English democracy)
  • *sel 'settlement'
  • *pelë- 'fortified high place', 'citadel' (Gr. polis 'city', Sanskrit (Sk.) púr)
  • *dhúno- 'fortified, enclosed place'(Celtic (Ct.) *dún-o- 'hill, stronghold', borrowed into Germanic as *túnaz 'fortified place', source of English town)
  • *bhergh 'high, hill, hill-forts' (English burg)(This might have actually been loaned into PIE)
  • *teutá- 'tribe' (Germanic(Gm.) *θeudá- 'people', seen in the English words Teuton, Dutch, and in German Deutsch 'German')
  • *rég- 'tribal king' (Norwegian rik 'realm', Latin réx (from reg-s, 'king (royal and priestly)'), Sk. *raja, rajan 'king, rajah'; these words are related to *reg- 'to move in a straight line')
  • *wí-ro- 'man, free man'
  • *ghos-ti 'guest, host, stranger', 'one with mutual obligations of hospitality' (compare Lt. hostis 'enemy'...'stranger')


  • *k(a)mb-jo- 'to exchange, to turn', derived from *skamb, *kamb 'to curve, bend' (compare Lt. cambiáre 'to exchange', seen in Spanish cambio 'change'; English change is borrowed from French)
  • *dap- 'to apportion (in exchange)'; suffixed *dap-no-is reflected in Lt. damnum 'damage entailing liability (for reparation), harm' (seen in damn, a loanword into English)
  • *wes- 'to buy'; in suffixed form *wes-no-, in Lt. vénum 'sale' (see loans in English vend, vendor)


  • grë-no- 'grain' (see English corn, kernel)
  • *jewo- 'grain'
  • *púro- 'grain'
  • *wrughjo- 'rye'
  • *bhares, *bhars- 'barley'
  • *al- 'to grind'
  • *melë-, *mel 'to grind, crush' (seen in English mill meal)
  • *sé- 'to sow' (the suffixed form *sé-ti- is reflected in Gm. *sédiz 'seed')(see English 'sow', 'seed')
  • *arë- 'to plough', arë-trom- 'plough' (compare the loanword arable in English)
  • *prk- 'furrow', 'trench' (seen in English furrow), derived from *perk- 'to dig out, tear out'
  • *solk-o- seen in Lt. sulcus 'furrow, groove' (derived from *selk- 'to draw, pull')
  • *wogwh-ini- 'ploughshare, wedge'
  • *jug-o- 'yoke' (derived from jeug- 'to join)
  • *serp- 'sickle, hook'
  • *kerp- 'to harvest, gather, pluck'
  • *gwerë-na- 'millstone, quern' (derived from *gwerë- 'heavy' (see English quern)
  • *agro- 'field, fallow land on which cattle were driven' (from *ag- 'to drive') (see English acre)

Domestic Animals

  • *gwou- 'bull, ox, cow' (English cow)
  • *owi- 'sheep' (see English ewe)
  • *agwh-no- 'lamb'
  • *aig- 'goat' (see English aegis)
  • *ghaido- 'goat' (English goat)
  • *sú- 'pig' (in suffixed form *suë-íno 'swine')(See English sow, swine)
  • *porko- 'young pig'
  • *kwon- 'dog' (see English hound)
  • *ekwo- 'horse' (Gr. hippos, Lt. equus, seen in Spanish yegua 'mare'; see loans in English equine, equestrian)(the horse was extremely important to the the rapid expansion of Indo-Europeans in the late third and early second millennia BC)
  • *ukws-en- 'bull, ox' (English ox)
  • *peku- 'wealth, moveable property, livestock' (see German Vieh 'cattle'; see English fee, fief); suffixed *peku-n- gives Lt. pecúnia 'property, wealth' (see the borrowing in English pecuniary)


  • *wegh- 'to go, transport in a vehicle' (see English way)
  • *wogh-no 'vehicle, wagon' (derived from *wegh- 'to go, transport in a vehicle') (English wagon, wain)
  • *kw(e)kwl-o- 'circle, wheel' (derived from *kwel- 'to revolve, move around') (see English wheel)
  • *aks-lo- 'axle' (see *aks- 'axis')
  • *náu- 'boat'(Lt. návis 'ship'; see English loans navy, navigate)
  • *erë-, *ré- 'to row' (Gm. *ró-, English row)

Technology (tools, implements, metals, weapons, musical instruments)

  • *ajes- 'copper or bronze' (see English ore)
  • .
  • *ghel- 'yellow metal, to shine' (the suffixed form *ghl-to- 'gold' is seen in Gm., as in English gold)
  • *arg- 'silver, white metal, to shine' (Lt. argentum 'silver', seen in French argent 'silver, money')
  • *dheigh- 'to form, build, mold, shape' (see English dough)
  • *arku- 'bow and arrow' (unsertain whether it meant 'bow' or 'arrow'; perhaps used as a unit; compare Lt. arcus 'bow', Gm. arhwó, English arrow)
  • *krut- 'musical instrument'

Household and food terms

  • *aukw- 'cooking pot' (Lt. aulla 'cooking pot' is from the suffixed form *aukw-slá-, the source of Spanish olla 'pot, jug'; with a different suffix we see Gm. *uhw-na- 'oven', the source of English oven)
  • *bhë-g- 'to bake' (derived from bhé- 'to warm') (English bake)
  • *sal-, *sald-o- 'salt' (English salt)
  • *melit 'honey' (French miel, Spanish miel 'honey')
  • *medhu 'honey, mead' (English mead)

Clothing and textiles

  • *wes- 'to clothe' (Lt. vestis 'garment' is from *wes-ti-, the source of French vêtir and Spanish vestir, both 'to clothe, to dress')(English wear)
  • *jós- 'to gird (to belt, wear a girdle)
  • *teks- 'fabricate' (especially with an axe), 'to weave' (textile)
  • *sné-, né- 'to spin, sew'; the suffixed form *né-tlá- gives 'needle' (see German nähen 'to sew'; English needle)
  • *webh- 'to weave' (English weft, web)
  • *sjú- 'to sew, bind' (English sew)
  • *wlë-ná-, *welë- 'wool' (probably derived from *wel- 'to tear, pull')


  • *deiw-os 'god', djeu-pëter 'chief god' (Jupiter, Zeus) (related to *deiw- 'to shine', with derivatives 'sky', heaven, god')
  • *kred-dhë- 'to place trust, believe' (religious term, based on *kerd- 'heart' + *dhé 'to do, place') (see English credence, credo)
  • *wegwh- 'to preach, speak solemnly' (as in the English loans vow, devote)
  • *sengwh- 'prophesy', 'to sing, make incantations' (English sing)
  • *gwerë- 'to praise aloud' (see Lt. and French loanwords in English grace, grateful, agree, and also in the borrowing from Ct. bard)
  • *tjegw- 'to retreat with awe'
  • *gwhedh- 'to pray, ask' (see English bid, bead)
  • *ghow-é- 'to honor, worship, revere (English gawk)
  • *kailo- 'holy, whole' (see English holy, hallow)
  • *meldh- 'to pray, speak words to a deity' (source of English meld)
  • *prek- 'to ask, entreat, pray' (English pray)
  • *sak 'to sanctify', *sak-ro 'holy, sacred', *sakro-dhót- 'performer of sacred rites' (dhót 'doer') (seen in Spanish sacerdote 'priest')
  • *sep- 'to foster, serve, venerate (the dead)', *sep-el-jo- 'to bury' (see English loan sepulchre)
  • *spend- 'to make an offering, perform a rite, hence engage oneself by a ritual act, to pour a libation' (compare Lt. spondére 'to make a solemn promise, pledge, betroth'; see English respond, responsible)
  • *wet- 'to blow, inspire, spiritually arouse', in Gm. *wód-eno-/*wód-ono- 'raging, mad, inspired', hence 'spirit', name of the chief Teutonic god, Woden in English (seen in Wednesday, literally 'Woden's day')

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