Proto-Indo-European — the theoretical root language of the Indo-European language family — remains shrouded in more than enough mystery to keep linguists occupied for some time. Of the things we do know is that it was prolific as a mother tongue. There are almost 450 Indo-European languages spoken in the world today, and they’re among the most widespread in their influence. More than a third of the planet speaks one of these languages, which can be heard throughout Europe, a substantial part of South Asia, parts of the Middle East and the Americas.

The Indo-European family encompasses the Germanic languages (English, German, Dutch, Danish, Norwegian, Swedish, Icelandic), Gaelic (Irish, Welsh, Breton), Romance (French, Spanish, Italian, Portuguese, Romanian), Slavic (Russian, Ukrainian, Polish, Czech, Slovak, Serbo-Croatian, Bulgarian), Baltic (Latvian, Lithuanian), Albanian, Greek, Armenian, Indo-Aryan (Urdu, Hindi, Gujurati, Bengali, Marathi, Punjabi, Sindhi, Sinhala) and Iranian languages (Kurdish, Farsi, Pashto, Dari). It’s not always easy to get the whole crew together these days, but it does make for an epic family reunion.

How did such a big, diverse assortment of languages originate from one common ancestor? And what was that ancestor like? New research is bringing us closer to the source — and dispelling some previous theories about where Indo-European first originated.

What We’ve Known (Up Until Recently)

Among the things we’ve been able to determine, thus far, is that the ancestor Indo-European language was spoken around 6,000 years ago in the Caucus region (modern-day Ukraine and southern Russia), specifically throughout the highlands between the Black and Caspian Seas.

Written language only came about 2,500 years later, so we haven’t been able to rely on physical records. However, linguists, archaeologists, and anthropologists have been able to retroactively piece it together through the genetic imprints of its children, or its language descendants.

About 500 years ago, scholars first began to notice that Sanskrit and Latin had things in common, and this led to observations that hundreds of languages shared common root words. By the 19th century, we knew that all these languages descended from a single root Indo-European language. More recently, we’ve been able to rely on ancient DNA as well. 

As much as Proto-Indo-European remains a bit of a mystery, there have been attempts to recreate it. In 1868, German linguist August Schleicher wrote a fable using reconstructed PIE vocabulary called “The Sheep and the Horses,” also known today as Schleicher’s Fable. The fable has been updated over time to reflect new knowledge about PIE and the Bronze Age cultures that spoke it, although there’s no universally agreed upon standard. Below, University of Kentucky linguist Andrew Byrd demonstrates how he believes it would have sounded for Archaeology.

Ancient DNA Reveals New Clues

In 2015, it was discovered that DNA housed inside the petrous bone of the inner ear can survive for thousands of years, even in warm climates. This means that more recently, geneticists have been able to collaborate with linguists and anthropologists to piece together linguistic histories.

In the last decade, we’ve also discovered that Indo-European languages appear to have been spread by the Yamnaya, a group of horse-herding nomads who lived on the Eurasian steppe. This is in contrast to the earlier prevailing theory that it was spread by Anatolian farmers living in modern-day Turkey. 

Earlier hunter-gatherers from the highlands between the Black and Caspian Seas split off into two directions — one group went west to Anatolia, and one north to the steppe. Based on genetic evidence published in 2015, it seems that the Yamnaya took on a lot of the distribution from there, both of language and genetics.

Now, a new study led by teams at Harvard and the University of Vienna has drawn some conclusions about the even earlier origins of Indo-European, prior to its contact with the Yamnaya people, based on the DNA of 727 people who lived in the region spanning the Black Sea and western Iran. This research has more than doubled the amount of ancient DNA available for study from this region, and it also indicates that the ancestry of many Romans living during the Imperial period came mainly from Anatolia. In addition, it reveals more insight into how an ancestral Indo-European language might have become established in ancient Greece.

The genetic evidence suggests that Anatolia was relatively isolated from its neighbors, with almost no trace of Yamnaya ancestry. But there is evidence that Hittite was spoken there, which appears to have split off from the language spoken by the Yamnaya from a common Indo-European ancestor. Anatolia went on to become a hub of diverse populations (from the Caucasus, Mesopotamia and the Levant) that eventually homogenized into one genetic population, and remained “impermeable” to genes from Europe or the steppe.

The genetic data does support that the Yamnaya and Anatolian people shared common ancestry from the highlands of West Asia, with evidence of two major migrations from West Asia into the steppe.

We now know that there are direct descendants of the Yamnaya living in Armenia today. There are also traces of genes from the steppe population in Greece, suggesting that they integrated with the local population while introducing the early Indo-European language to the region (versus replacing them entirely, as they did in modern-day Germany and England). This is interesting because it raises the possibility that Indo-European served as a sort of lingua franca for speakers of diverse languages in the Balkan region. This is in contrast to how Indo-European became established in northern Europe, which was by domination of previously present populations.

The Future Of The Hunt For Proto-Indo-European

Though we’re getting closer to the source, there’s still more research needed to understand the population that the Yamnaya and Anatolians descended from. The geneticists have identified a need for more research into the cultures of West Asia, the Caucasus and the Eurasian steppe to identify some sort of link between the steppe and Anatolia, primarily via a population driving transformation in both regions.

“The discovery of such a ‘missing link’ (corresponding to Proto-Indo-Anatolians if our reconstruction is correct),” they write, “would bring to an end the centuries-old quest for a common source binding through language and some ancestry many of the peoples of Asia and Europe.”