English. French. Italian. Hindi. Greek. Russian. All these different languages can trace their roots to the same origin: Proto-Indo-European, spoken in 4000 BC in the steppe that crosses from Eastern Europe to Central Asia. Whether by migration, diffusion or conquest, the Indo-European languages spread west across Europe, east across Central Asia, and southeast towards India.

Laura Spinney writes about Proto-Indo-European—which never existed in a written form—and its many descendants in her latest book Proto: How One Ancient Language Went Global.

Laura Spinney is the author of Pale Rider: The Spanish Flu of 1918 and How It Changed the World (PublicAffairs, 2017), which has been translated into more than a dozen languages, and two novels. Her science writing has appeared in The Atlantic, National Geographic, Nature, The Economist, The Guardian, and elsewhere.

Nicholas Gordon has an MPhil from Oxford in International Relations and a BA from Harvard. He is a writer, editor and occasional radio host based in Hong Kong.