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.

“Usually you can hook people really easily by doing these funny little things,” Fitch said later. “But the Pirahã kids weren’t buying it, and neither were their parents.” Everett snorted. “It’s not part of their culture,” he said. “So they’re not interested.”

A few weeks earlier, I had called Fitch in Scotland, where he is a professor at the University of St. Andrews. “I’m seeing this as an exploratory fact-finding trip,” he told me. “I want to see with my own eyes how much of this stuff that Dan is saying seems to check out.”

Everett is known among linguistics experts for orneriness and an impatience with academic decorum. He was born into a working-class family in Holtville, a town on the California-Mexico border, where his hard-drinking father, Leonard, worked variously as a bartender, a cowboy, and a mechanic. “I don’t think we had a book in the house,” Everett said. “To my dad, people who taught at colleges and people who wore ties were ‘sissies’—all of them. I suppose some of that is still in me.” Everett’s chief exposure to intellectual life was through his mother, a waitress, who died of a brain aneurysm when Everett was eleven. She brought home Reader’s Digest condensed books and a set of medical encyclopedias, which Everett attempted to memorize. In high school, he saw the movie “My Fair Lady” and thought about becoming a linguist, because, he later wrote, Henry Higgins’s work “attracted me intellectually, and because it looked like phoneticians could get rich.”

As a teen-ager, Everett played the guitar in rock bands (his keyboardist later became an early member of Iron Butterfly) and smoked pot and dropped acid, until the summer of 1968, when he met Keren Graham, another student at El Capitan High School, in Lakeside. The daughter of Christian missionaries, Keren was brought up among the Satere people in northeastern Brazil. She invited Everett to church and brought him home to meet her family. “They were loving and caring and had all these groovy experiences in the Amazon,” Everett said. “They supported me and told me how great I was. This was just not what I was used to.” On October 4, 1968, at the age of seventeen, he became a born-again Christian. “I felt that my life had changed completely, that I had stepped from darkness into light—all the expressions you hear.” He stopped using drugs, and when he and Keren were eighteen they married. A year later, the first of their three children was born, and they began preparing to become missionaries.

In 1976, after graduating with a degree in Foreign Missions from the Moody Bible Institute of Chicago, Everett enrolled with Keren in the Summer Institute of Linguistics, known as S.I.L., an international evangelical organization that seeks to spread God’s Word by translating the Bible into the languages of preliterate societies. They were sent to Chiapas, Mexico, where Keren stayed in a hut in the jungle with the couple’s children—by this time, there were three—while Everett underwent gruelling field training. He endured fifty-mile hikes and survived for several days deep in the jungle with only matches, water, a rope, a machete, and a flashlight.

The couple were given lessons in translation techniques, for which Everett proved to have a gift. His friend Peter Gordon, a linguist at Columbia University who has published a paper on the absence of numbers in Pirahã, says that Everett regularly impresses academic audiences with a demonstration in which he picks from among the crowd a speaker of a language that he has never heard. “Within about twenty minutes, he can tell you the basic structure of the language and how its grammar works,” Gordon said. “He has incredible breadth of knowledge, is really, really smart, knows stuff inside out.” Everett’s talents were obvious to the faculty at S.I.L*.*, who for twenty years had been trying to make progress in Pirahã, with little success. In October, 1977, at S.I.L.’s invitation, Everett, Keren, and their three small children moved to Brazil, first to a city called Belém, to learn Portuguese, and then, a year later, to a Pirahã village at the mouth of the Maici River. “At that time, we didn’t know that Pirahã was linguistically so hard,” Keren told me.

There are about three hundred and fifty Pirahã spread out in small villages along the Maici and Marmelos Rivers. The village that I visited with Everett was typical: seven huts made by propping palm-frond roofs on top of four sticks. The huts had dirt floors and no walls or furniture, except for a raised platform of thin branches to sleep on. These fragile dwellings, in which a family of three or four might live, lined a path that wound through low brush and grass near the riverbank. The people keep few possessions in their huts—pots and pans, a machete, a knife—and make no tools other than scraping implements (used for making arrowheads), loosely woven palm-leaf bags, and wood bows and arrows. Their only ornaments are simple necklaces made from seeds, teeth, feathers, beads, and soda-can pull-tabs, which they often get from traders who barter with the Pirahã for Brazil nuts, wood, and sorva (a rubbery sap used to make chewing gum), and which the tribe members wear to ward off evil spirits.

Unlike other hunter-gatherer tribes of the Amazon, the Pirahã have resisted efforts by missionaries and government agencies to teach them farming. They maintain tiny, weed-infested patches of ground a few steps into the forest, where they cultivate scraggly manioc plants. “The stuff that’s growing in this village was either planted by somebody else or it’s what grows when you spit the seed out,” Everett said to me one morning as we walked through the village. Subsisting almost entirely on fish and game, which they catch and hunt daily, the Pirahã have ignored lessons in preserving meats by salting or smoking, and they produce only enough manioc flour to last a few days. (The Kawahiv, another Amazonian tribe that Everett has studied, make enough to last for months.) One of their few concessions to modernity is their dress: the adult men wear T-shirts and shorts that they get from traders; the women wear plain cotton dresses that they sew themselves.

“For the first several years I was here, I was disappointed that I hadn’t gone to a ‘colorful’ group of people,” Everett told me. “I thought of the people in the Xingu, who paint themselves and use the lip plates and have the festivals. But then I realized that this is the most intense culture that I could ever have hoped to experience. This is a culture that’s invisible to the naked eye, but that is incredibly powerful, the most powerful culture of the Amazon. Nobody has resisted change like this in the history of the Amazon, and maybe of the world.”

According to the best guess of archeologists, the Pirahã arrived in the Amazon between ten thousand and forty thousand years ago, after bands of Homo sapiens from Eurasia migrated to the Americas over the Bering Strait. The Pirahã were once part of a larger Indian group called the Mura, but had split from the main tribe by the time the Brazilians first encountered the Mura, in 1714. The Mura went on to learn Portuguese and to adopt Brazilian ways, and their language is believed to be extinct. The Pirahã, however, retreated deep into the jungle. In 1921, the anthropologist Curt Nimuendajú spent time among the Pirahã and noted that they showed “little interest in the advantages of civilization” and displayed “almost no signs of permanent contact with civilized people.”

S.I.L. first made contact with the Pirahã nearly fifty years ago, when a missionary couple, Arlo and Vi Heinrichs, joined a settlement on the Marmelos. The Heinrichses stayed for six and a half years, struggling to become proficient in the language. The phonemes (the sounds from which words are constructed) were exceedingly difficult, featuring nasal whines and sharp intakes of breath, and sounds made by popping or flapping the lips. Individual words were hard to learn, since the Pirahã habitually whittle nouns down to single syllables. Also confounding was the tonal nature of the language: the meanings of words depend on changes in pitch. (The words for “friend” and “enemy” differ only in the pitch of a single syllable.) The Heinrichses’ task was further complicated because Pirahã, like a few other Amazonian tongues, has male and female versions: the women use one fewer consonant than the men do.

“We struggled even getting to the place where we felt comfortable with the beginning of a grammar,” Heinrichs told me. It was two years before he attempted to translate a Bible story; he chose the Prodigal Son from the Book of Luke. Heinrichs read his halting translation to a Pirahã male. “He kind of nodded and said, in his way, ‘That’s interesting,’ ” Heinrichs recalled. “But there was no spiritual understanding—it had no emotional impact. It was just a story.” After suffering repeated bouts of malaria, the couple were reassigned by S.I.L. to administrative jobs in the city of Brasília, and in 1967 they were replaced with Steve Sheldon and his wife, Linda.

Sheldon earned a master’s degree in linguistics during the time he spent with the tribe, and he was frustrated that Pirahã refused to conform to expected patterns—as he and his wife complained in workshops with S.I.L. **{: .small}consultants. “We would say, ‘It just doesn’t seem that there’s any way that it does X, Y, or Z,’ ” Sheldon recalled. “And the standard answer—since this typically doesn’t happen in languages—was ‘Well, it must be there, just look a little harder.’ ” Sheldon’s anxiety over his slow progress was acute. He began many mornings by getting sick to his stomach. In 1977, after spending ten years with the Pirahã, he was promoted to director of S.I.L. in Brazil and asked the Everetts to take his place in the jungle.

Everett and his wife were welcomed by the villagers, but it was months before they could conduct a simple conversation in Pirahã. “There are very few places in the world where you have to learn a language with no language in common,” Everett told me. “It’s called a monolingual field situation.” He had been trained in the technique by his teacher at S.I.L., the late Kenneth L. Pike, a legendary field linguist and the chairman of the linguistics department at the University of Michigan. Pike, who created a method of language analysis called tagmemics, taught Everett to start with common nouns. “You find out the word for ‘stick,’ ” Everett said. “Then you try to get the expression for ‘two sticks,’ and for ‘one stick drops to the ground,’ ‘two sticks drop to the ground.’ You have to act everything out, to get some basic notion of how the clause structure works—where the subject, verb, and object go.”

The process is difficult, as I learned early in my visit with the Pirahã. One morning, while applying bug repellent, I was watched by an older Pirahã man, who asked Everett what I was doing. Eager to communicate with him in sign language, I pressed together the thumb and index finger of my right hand and weaved them through the air while making a buzzing sound with my mouth. Then I brought my fingers to my forearm and slapped the spot where my fingers had alighted. The man looked puzzled and said to Everett, “He hit himself.” I tried again—this time making a more insistent buzzing. The man said to Everett, “A plane landed on his arm.” When Everett explained to him what I was doing, the man studied me with a look of pitying contempt, then turned away. Everett laughed. “You were trying to tell him something about your general state—that bugs bother you,” he said. “They never talk that way, and they could never understand it. Bugs are a part of life.”

“O.K.,” I said. “But I’m surprised he didn’t know I was imitating an insect.”

“Think of how cultural that is,” Everett said. “The movement of your hand. The sound. Even the way we represent animals is cultural.”

Everett had to bridge many such cultural gaps in order to gain more than a superficial grasp of the language. “I went into the jungle, helped them make fields, went fishing with them,” he said. “You cannot become one of them, but you’ve got to do as much as you can to feel and absorb the language.” The tribe, he maintains, has no collective memory that extends back more than one or two generations, and no original creation myths. Marco Antonio Gonçalves, an anthropologist at the Federal University of Rio de Janeiro, spent eighteen months with the Pirahã in the nineteen-eighties and wrote a dissertation on the tribe’s beliefs. Gonçalves, who spoke limited Pirahã, agrees that the tribe has no creation myths but argues that few Amazonian tribes do. When pressed about what existed before the Pirahã and the forest, Everett says, the tribespeople invariably answer, “It has always been this way.”

Everett also learned that the Pirahã have no fixed words for colors, and instead use descriptive phrases that change from one moment to the next. “So if you show them a red cup, they’re likely to say, ‘This looks like blood,’ ” Everett said. “Or they could say, ‘This is like vrvcum’—a local berry that they use to extract a red dye.”