Dan Everett believes that Pirahã undermines Noam Chomsky’s idea of a universal grammar. Photograph by Martin Schoeller. Correction appended. One morning last July, in the rain forest of northwestern Brazil, Dan Everett, an American linguistics professor, and I stepped from the pontoon of a Cessna floatplane onto the beach bordering the Maici River, a narrow, sharply meandering tributary of the Ama