Table of Contents Under Paris You’ll find bones, stones, miles of tunnels, and legal—and illegal—tourism. Features Feather Feather Evolution Who had them first, why did they spring up (hint: sex may have had a lot to do with it), and when did they take flight? Opium Wars A key step toward peace in Afghanistan is to wipe out poppies—one of the country’s most profitable crops. Artificial Reef From Relics to Reefs Fish can’t resist a sunken subway car, tank, or ship. Snub-Nosed Monkeys Its quirky face may help China’s snub-nosed monkey cope in a brutal clime. Concussions The Big Idea: Brain Trauma Even small hits to the head can lead to brain deterioration. Editor's Note In this issue, Robert Draper and David Guttenfelder cover Afghanistan's dangerous opium story. Flashback: Feathers in Her Cap In an image from 1926, Mae Vavrea tops off her turban with a Japanese bantam rooster. Visions of Earth Each month, National Geographic features breathtaking photographs in Visions of Earth.