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 Amazon. On the bank above us were some thirty people—short, dark-skinned men, women, and children—some clutching bows and arrows, others with infants on their hips. The people, members of a hunter-gatherer tribe called the Pirahã, responded to the sight of Everett—a solidly built man of fifty-five with a red beard and the booming voice of a former evangelical minister—with a greeting that sounded like a profusion of exotic songbirds, a melodic chattering scarcely discernible, to the uninitiated, as human speech. Unrelated to any other extant tongue, and based on just eight consonants and three vowels, Pirahã has one of the simplest sound systems known. Yet it possesses such a complex array of tones, stresses, and syllable lengths that its speakers can dispense with their vowels and consonants altogether and sing, hum, or whistle conversations. It is a language so confounding to non-natives that until Everett and his wife, Keren, arrived among the Pirahã, as Christian missionaries, in the nineteen-seventies, no outsider had succeeded in mastering it. Everett eventually abandoned Christianity, but he and Keren have spent the past thirty years, on and off, living with the tribe, and in that time they have learned Pirahã as no other Westerners have.

“Xaói hi gáísai xigíaihiabisaoaxái ti xabiíhai hiatíihi xigío hoíhi,” Everett said in the tongue’s choppy staccato, introducing me as someone who would be “staying for a short time” in the village. The men and women answered in an echoing chorus, “Xaói hi goó kaisigíaihí xapagáiso.”

Everett turned to me. “They want to know what you’re called in ‘crooked head.’ ”

“Crooked head” is the tribe’s term for any language that is not Pirahã, and it is a clear pejorative. The Pirahã consider all forms of human discourse other than their own to be laughably inferior, and they are unique among Amazonian peoples in remaining monolingual. They playfully tossed my name back and forth among themselves, altering it slightly with each reiteration, until it became an unrecognizable syllable. They never uttered it again, but instead gave me a lilting Pirahã name: Kaaxáoi, that of a Pirahã man, from a village downriver, whom they thought I resembled. “That’s completely consistent with my main thesis about the tribe,” Everett told me later. “They reject everything from outside their world. They just don’t want it, and it’s been that way since the day the Brazilians first found them in this jungle in the seventeen-hundreds.”

Everett, who this past fall became the chairman of the Department of Languages, Literature, and Cultures at Illinois State University, has been publishing academic books and papers on the Pirahã (pronounced pee-da-HAN) for more than twenty-five years. But his work remained relatively obscure until early in 2005, when he posted on his Web site an article titled “Cultural Constraints on Grammar and Cognition in Pirahã,” which was published that fall in the journal Cultural Anthropology. The article described the extreme simplicity of the tribe’s living conditions and culture. The Pirahã, Everett wrote, have no numbers, no fixed color terms, no perfect tense, no deep memory, no tradition of art or drawing, and no words for “all,” “each,” “every,” “most,” or “few”—terms of quantification believed by some linguists to be among the common building blocks of human cognition. Everett’s most explosive claim, however, was that Pirahã displays no evidence of recursion, a linguistic operation that consists of inserting one phrase inside another of the same type, as when a speaker combines discrete thoughts (“the man is walking down the street,” “the man is wearing a top hat”) into a single sentence (“The man who is wearing a top hat is walking down the street”). Noam Chomsky, the influential linguistic theorist, has recently revised his theory of universal grammar, arguing that recursion is the cornerstone of all languages, and is possible because of a uniquely human cognitive ability.

Steven Pinker, the Harvard cognitive scientist, calls Everett’s paper “a bomb thrown into the party.” For months, it was the subject of passionate debate on social-science blogs and Listservs. Everett, once a devotee of Chomskyan linguistics, insists not only that Pirahã is a “severe counterexample” to the theory of universal grammar but also that it is not an isolated case. “I think one of the reasons that we haven’t found other groups like this,” Everett said, “is because we’ve been told, basically, that it’s not possible.” Some scholars were taken aback by Everett’s depiction of the Pirahã as a people of seemingly unparalleled linguistic and cultural primitivism. “I have to wonder whether he’s some Borgesian fantasist, or some Margaret Mead being stitched up by the locals,” one reader wrote in an e-mail to the editors of a popular linguistics blog.

I had my own doubts about Everett’s portrayal of the Pirahã shortly after I arrived in the village. We were still unpacking when a Pirahã boy, who appeared to be about eleven years old, ran out from the trees beside the river. Grinning, he showed off a surprisingly accurate replica of the floatplane we had just landed in. Carved from balsa wood, the model was four feet long and had a tapering fuselage, wings, and pontoons, as well as propellers, which were affixed with small pieces of wire so that the boy could spin the blades with his finger. I asked Everett whether the model contradicted his claim that the Pirahã do not make art. Everett barely glanced up. “They make them every time a plane arrives,” he said. “They don’t keep them around when there aren’t any planes. It’s a chain reaction, and someone else will do it, but then eventually it will peter out.” Sure enough, I later saw the model lying broken and dirty in the weeds beside the river. No one made another one during the six days I spent in the village.

In the wake of the controversy that greeted his paper, Everett encouraged scholars to come to the Amazon and observe the Pirahã for themselves. The first person to take him up on the offer was a forty-three-year-old American evolutionary biologist named Tecumseh Fitch, who in 2002 co-authored an important paper with Chomsky and Marc Hauser, an evolutionary psychologist and biologist at Harvard, on recursion. Fitch and his cousin Bill, a sommelier based in Paris, were due to arrive by floatplane in the Pirahã village a couple of hours after Everett and I did. As the plane landed on the water, the Pirahã, who had gathered at the river, began to cheer. The two men stepped from the cockpit, Fitch toting a laptop computer into which he had programmed a week’s worth of linguistic experiments that he intended to perform on the Pirahã. They were quickly surrounded by curious tribe members. The Fitch cousins, having travelled widely together to remote parts of the world, believed that they knew how to establish an instant rapport with indigenous peoples. They brought their cupped hands to their mouths and blew loon calls back and forth. The Pirahã looked on stone-faced. Then Bill began to make a loud popping sound by snapping a finger of one hand against the opposite palm. The Pirahã remained impassive. The cousins shrugged sheepishly and abandoned their efforts.