Humans, it has long been thought, are the only animal to engage in economic activity. But what if we've had it exactly backward?

Daniel Ek, a 23-year-old Swede who grew up on pirated music, made the record labels an offer they couldn’t refuse: a legal platform to stream all the world’s music. Spotify reversed the labels’ fortunes, made Ek rich, and thrilled millions of music fans. But what has it done for all those musicians stuck in the long tail?