Star. Stjarna. Stare. Thousands of miles apart, people look up at the night sky and use the same word to describe what they see.Listen to these English, Icelandic and Iranic words and you can hear echoes of one of the most extraordinary journeys in humanity’s past. All three of these languages – and hundreds more – share a single ancient ancestor.Five millennia ago, in a mysterious Big Bang of its own, this proto tongue exploded, forming new worlds as it spread east and west. Today, nearly half of humanity speaks an Indo-European language. How did this happen?..

In Pale Rider, Laura Spinney recounts the story of an overlooked pandemic, tracing it from Alaska to Brazil, from Persia to Spain, and from South Africa to Odessa. She shows how the pandemic was shaped by the interaction of a virus and the humans it encountered; and how this devastating natural experiment put both the ingenuity and the vulnerability of humans to the test.