Washington Monthly: Until forty years ago, the Surui people spent their days roaming the Brazilian Amazon with bows and arrows, hunting monkeys and wild pigs. Their only contact with the outside world was with the rubber tappers who occasionally ventured through their territory. Then, beginning in the late 1960s, the Brazilian government laid a 2,000-mile highway through the heart of the jungle. Lured by the promise of cheap, fertile land, thousands of poor farmers boarded buses, rickety pickups, and …