Ethnologue (an amazing source for linguistics information and data) reports that, as of 2025, 3.39 billion people speak a language in the Indo-European family. Before the colonization of the Western hemisphere, Indo-European languages were spoken from Ireland to India, from Scandinavia and Russia to Spain. In Proto: How One Ancient Language Went Global, Laura Spinney follows the threads of linguistic reconstruction, genetic research, and archaeology to document what we think we know about Proto-Indo-European, the language that birthed descendants as diverse as Gaelic, Sanskrit, Estonian, English, and Bengali. (Ethnologue cites 455 languages in the Indo-European family.)
As far as linguists know, Proto-Indo-European may have been spoken somewhere in what is now Ukraine between six and four thousand years ago. We have no direct evidence of the language. Writing hadn’t been invented yet. The language was first proposed by linguists like Marcus Zuerius van Boxhorn (1600s), Gaston-Laurent Coeurdoux (1700s), and William Jones (1700s). These men (among others) spotted similarities between languages as disparate as Sanskrit, Lithuanian, and other languages spoken in Europe, India, and points in between. Two of the best examples of the similarities they spotted are the words for “mother” and “father”:
Documenting examples like these and creating sound change laws (like the change from a “p” sound to an “f” sound like the one you can see in the example for “father” above) have helped linguists create a family tree for the Indo-European language and reconstruct hundreds of words that might have existed in Proto-Indo-European.
Spinney focuses more on the genetic research and archaeology parts of the Indo-European family story. She is much more interested in talking about how the language and its descendants came to be spoken in so many places, by so many people. Most evidence points to a homeland in the steppe land in what is now Ukraine. From there, the language may have migrated to the Anatolian peninsula before splitting into the Indo-Iranian branch and the European branches. (One branch, Tocharian, ended up being spoken in the remote Taklamakan Desert in what is now China before it died out.) People took their languages with them when they migrated, went to war, and traded. It’s amazing what scientists and archaeologists have been able to discover in the bones and artifacts left behind.
That said, Spinney is clear that there are still a lot of open debates in the story of Proto-Indo-European: is the homeland in Eurasia? Why did Indo-European languages outcompete so many other languages in their various paths? (Basque is one of the few non-Indo-European languages traditionally spoken in Europe and is, interestingly, a linguistic isolate.) How did the Tocharians end up all the way over there? What can we glean about the culture and beliefs of Proto-Indo-European speakers?
Because of these questions—and the very light coverage of linguistics in general—Proto is more of an introduction than an in-depth exploration. It’s not a perfect guide. There were two errors about different varieties of English in a footnote early in the book, so I read this book in close proximity to my library’s website and Wikipedia so that I could fact-check as I read. I am comfortable recommending to curious readers who want an overview. It certainly provides enough background in the way of terminology and names to help guide further research.
I received a free copy of this book from the publisher via NetGalley, for review consideration.