SMOKE AND ASHES: Opium’s Hidden Histories, by Amitav Ghosh Biographies of humble things that their authors claimed had “changed the world” — chronometers, salt, potatoes and even the color mauve — were a turn-of-the-21st-century publishing phenomenon. Looking back, they seem fixated on European heroes and their achievements. As Amitav Ghosh observes at the beginning of his bracing new history of the global opium trade, it’s hard to see past a Western conception of the world that “looms so large that it obscures everything else.” “Smoke and Ashes” is the story…