What Is the Proto-Indo-European Language?

Proto-Indo-European is the key to understanding why words like "mother" and "father" are so similar in so many different languages.

Neal Whitman, Writing for
10-minute read
Episode #593

The ‘Discovery’ of Proto-Indo-European

The discovery of the Indo-European language family happened a century before de Saussure proposed his mystery consonants--and maybe even earlier, depending on whom you believe. The story of its discovery is famous among linguists. Like many famous stories, it’s not entirely true, but we’ll start with the popular version. It begins with Sir William Jones, a British judge in Calcutta, India, in the late 1700s, who knew a lot of languages. In particular, he knew Latin and Greek, having had a classical education in England, and he had also learned the ancient Indian language Sanskrit, because that was the official language in the courts he would be working in. During his years in India he gave an annual talk to a club he had helped found, called the Royal Asiatic Society. In the third of these annual talks, he discussed the origin and history of the people of India, and in one famous passage talked about a common ancestral language for Latin, Greek, and Sanskrit. He said that the Sanskrit language was so similar to Latin and Greek that, in his words, “no philologer could examine them all three without believing them to have sprung from some common source, which, perhaps, no longer exists.” (4)

A philologer, in case you’re wondering, is someone who studies language in its written form, and in fact, Jones’s remarks about Latin, Greek, and Sanskrit have become known as “the philologer passage.” The philologer passage is usually credited with kicking off a century of research and discoveries showing that not only were Latin, Greek, and Sanskrit linguistic cousins to each other, but also that many other languages originating in Europe, Asia Minor, and the Indian subcontinent were in that same family. This geographic distribution is what gave this family of languages its name, with “Indo-“ coming from “Indos,” the Greek word for India. 

To get an idea what Jones was talking about, let’s take our example of the words for “mother” and “father” again. Remember that the Latin word for “mother” is “māter,” and the Ancient Greek is “mētēr.” In Sanskrit, the word is “mātr.” The Latin word for “father” is “pater” (“PAH-ter”); in Ancient Greek it’s “patēr” (“pah-TARE”); and in Sanskrit, it’s “pitr.” Many other such similarities can be found. 

English’s Place in the Indo-European Family

So how does English fit into this picture? English is a member of the Germanic language subfamily, which also includes Swedish, Norwegian, Icelandic, and German, as well as Gothic, a language that was last spoken more than 1,000 years ago. (5) One of the main changes that distinguish Germanic languages from other Indo-European languages is a pattern known as Grimm’s Law. It’s named after Jakob Grimm, who was one of the Brothers Grimm, famous for their collection of European folk tales. But he was also a philologer, and in the 1820s, he published a grammar of German, and in that grammar he described a pattern of several systematic sound changes that happened in the dialect of Proto-Indo-European that eventually became Proto-Germanic. (6) This is another language that was never written, but it’s the language from which all our modern Germanic languages developed. One of those changes involved the sounds P, T, and K, and in particular, we’re interested in the P sound. As the Proto-Germanic language began to split off from Proto-Indo-European, its speakers began to pronounce P as F. So while the Latin, Greek, and Sanskrit words for “father” begin with P, the word in English and other Germanic languages begins with an f sound. In German, it’s “Vater" (“fah-teh”); in Swedish, it’s “far”; and in Gothic, it’s “fadar.” 

This P-to-F sound didn’t just affect the Proto-Indo-European word for “father.” One of the amazing discoveries that early historical linguists made is that sound changes eventually affect every word that has the relevant sound. This is why English has the word “fish” where Latin has “piscis”; “fire” where ancient Greek has “pyr-“; and “foot” where Latin has “ped-“ and Greek has “pod-.”

In addition to the Germanic subfamily, some other main subfamilies of Indo-European are the Celtic languages, including Welsh, Irish and Scots Gaelic; the Slavic languages, such as Russian, Ukrainian, Serbian, Croatian, and Macedonian; and the Indo-Iranian languages, which include Persian, Dari, and Pashto, as well as Sanskrit and all of its descendant languages, such as Hindi, Bengali, and Nepali.

Where Did the Original Proto-Indo-European Speakers Live?

With such a wide geographic range of Indo-European languages, it’s natural to wonder where the original speakers of Proto-Indo-European lived. This isn’t entirely settled, but the most widely believed scenario is that they lived about 5,000 years ago in the area between the Black Sea and the Caspian Sea, in the present-day region of Russia that lies between Ukraine to the west, and Kazakhstan to the east. (7) Some of the words that have been reconstructed in Proto-Indo-European tell us a bit about these people’s culture. For example, they must have used wheels, because several Indo-European languages have a word for “wheel” or “circle” that allow us to reconstruct a Proto-Indo-European word for it. In Old English, our word “wheel” was “hweogol,” and if you run that through Grimm’s Law and the other known sound changes in reverse, you arrive at “kwekwlos” as the Proto-Indo-European word. (8) In Greek, this word developed into the word “kuklos,” which you might recognize as the Greek root that we pronounce as “cycle.” In Latin, it shows up as “circus.” The Proto-Indo-European word “kwekwlos” is even the source of the Sanskrit word for “wheel,” “chakra,” which we’ve borrowed into English as a piece of yoga-related vocabulary--along with the word “yoga,” too. 

A More Modern Take on the Proto-Indo-European Story

I said earlier that the story of William Jones and the discovery of Proto-Indo-European wasn’t entirely true. In an article published in 2006, linguist Lyle Campbell pointed out several problems with this story. (9) First of all, Jones incorrectly classified several languages, such as Arabic, as Indo-European languages. Furthermore, he didn’t classify several other languages as Indo-European that some of his contemporaries correctly did, such as the Slavic and Germanic languages. Not only that, but even for some of the languages that he did correctly include, his reasoning was unsound, and not acceptable in modern linguistics. And finally, he wasn’t even the first one to propose a common ancestral language for Greek, Latin, and Sanskrit. That idea had been around for at least 100 years, and the relationship between these languages really is so obvious that it didn’t require modern comparative linguistic techniques to make the call.

Even so, in the more than 200 years since Jones’s remarks, the comparative method has helped establish not only the Indo-European family of languages, but many other language families of the world too. 


1. Hock, Hans Henrich. 1991. Principles of Historical Linguistics, 2ed. Berlin: Mouton de Gruyter. pp. 545-550.

2. Hock, Hans Henrich, and Joseph, Brian D. 1996. Language History, Language Change, and Language Relationship. Berlin: Mouton de Gruyter. p. 96.

3. Hock 1991, pp. 545-550.

4. Jones, Sir William. 1786. “The third anniversary discourse, delivered 2d February, 1786: on the Hindus”, Asiatick Researches 1, 415-431. (cited in Campbell 2006) 

5.  Bennett, William H. 1980. An Introduction to the Gothic Language. New York: The Modern Language Association of America.

6.  Hock and Joseph 1996, pp. 39-40.

7. “Kurgan hypothesis.” Wikipedia. https://en.wikipedia.org/wiki/Kurgan_hypothesis. Accessed 25 October 2017; last edited 25 October 2017

8. Hock and Joseph 1996, p. 469.

9. Campbell, Lyle. 2006. “Why Sir William Jones got it all wrong, or Jones’ role in how to establish language families.” International Journal of Basque Linguistics and Philology (ASJU) 50, 245-264.


About the Author

Neal Whitman, Writing for Grammar Girl

Neal Whitman PhD is an independent writer and consultant specializing in language and grammar and a member of the Reynoldsburg, Ohio, school board. You can find him at literalminded.wordpress.com.