Two environmental terms, bigí and xoí, are fundamental to understanding the Pirahã worldview. One day, after a rain, Everett recorded the phrase bigí xihoíxaagá for muddy ground, and then he pointed to the cloudy sky and received the same phrase. Confused, Everett eventually deduced that bigí marks boundaries in a layered universe, separating worlds above the sky and beneath the ground.

When Kóhoibiíihíai’s daughter contracted malaria, Everett explained mosquitoes and blood. Kóhoibiíihíai interrupted to counter that his daughter was sick because she stepped on “a leaf from above” (115). When beings from the upper bigí visit the lower bigí, they leave leaves that cause sickness when stepped on.

The term xoí initially seemed to mean “jungle,” but Everett soon realized that it labels the entire space between bigís—the biosphere itself. “I am going into the xoí” means entering the jungle, “Don’t move in the xoí” means remain motionless, and “The xoí is pretty” describes a cloudless day (116).

These elements of the language were perplexing, but Everett was even more surprised to discover that Pirahã lacks numbers and counting. What he thought were number words proved to be relative quantities; the Pirahãs use the same term for two small fish or one medium fish because both represent similar volume. They never use fingers or body parts to count. In 1980, Everett and Keren conducted eight months of nightly classes attempting to teach the Pirahãs to count to 10 in Portuguese. Not one person learned to count to 10 or perform simple addition, despite attending the classes regularly and “with much enthusiasm” (118). The Pirahãs ultimately concluded that they couldn’t learn the material and abandoned the classes. Everett concludes that they simply don’t value this knowledge and resist the concept of a single correct answer.

When Pirahãs “write,” they make identical repetitive marks and “read” stories about their day, unconcerned that their symbols are all the same or that there are correct written forms. They can’t draw a straight line without coaching and never replicate it in subsequent attempts. They see the process as fun rather than requiring correctness.

The language also lacks simple color words. What Steve Sheldon analyzed as color terms are actually phrases: “blood is dirty” (black), “it sees” or “it is transparent” (white), “it is blood” (red and yellow), and “it is temporarily being immature” (green and blue; 118).

Pirahã also lacks quantifiers like “all,” “each,” and “every.” Instead, they use phrases with “bigness” and “smallness.” The words báaiso (whole) and gíiái (part) might seem like quantifiers, but an example reveals otherwise. When someone says they will buy an entire anaconda skin and then a piece is removed, a Pirahã speaker still says he bought the “whole” thing. In English, “all” means every single entity with nothing left over. Pirahã words lack these truth conditions.

These accumulating discoveries—no numbers, no color terms, no quantifiers—prompted Everett to examine Pirahã stories for deeper cultural patterns. He quickly discovered that all Pirahã stories are about immediate experience. One day, Kaaboogi killed a massive panther. In the original telling, he described in detail his dog being torn in half by the panther before he killed it with a 28-gauge shotgun. The transcribed story that Everett recorded is “massively repetitive,” for rhetorical purposes: The repetition expresses excitement, ensures clarity amid background noise, and provides stylish narrative flow. It’s a typical example of Pirahã storytelling, which focuses on the eyewitness testimony of the speaker. 

Learning the word xibipíio helped Everett further unpack the importance of immediate experience for the Pirahã. Initially, he thought the word meant “just now,” used to describe when someone or something has just arrived or departed. Then, Everett heard Pirahãs describe a flickering match as xibipíío-ing and realized that the word describes entities coming into or going out of perception. This hunch was confirmed when children shouted the word at the precise moment when a canoe disappeared around a river bend; xibipíio focuses on the act of perception itself rather than who is traveling.

Everett explains that xibipíio represents an important Pirahã cultural value that has no direct translation into English. The term refers to “experiential liminality”—the idea of coming into or going out of perception, or “being on the boundary of experience” (128). This concept reinforces the cultural value of limiting speech to things personally witnessed or heard from a living eyewitness. Even cosmological knowledge requires eyewitnesses, as beings from other layers traverse bigís and are seen in the jungle. Dreams are also classified as real experiences since one is an eyewitness to them.

This mounting evidence led Everett to formulate the “immediacy of experience principle”: “Declarative Pirahã utterances contain only assertions related directly to the moment of speech, either experienced by the speaker or witnessed by someone alive during the lifetime of the speaker” (131). This concept explains the absence of perfect tenses and embedded sentences in the grammar, the simple kinship system (which only includes relatives witnessable in a normal lifespan), and the lack of creation myths, traditional history, and folklore.

In terms of creation, the Pirahãs believe that “things were not made” (134). They have no creator god, only spirits that take the form of physical things like animals or trees. Like everything else, these spirits must be evaluated empirically. As an example, Everett shares the story “Xipoógi and the Jaguar,” recorded by Steve Sheldon and narrated by Kaboibagi, which describes Xitihoixoí being attacked by a jaguar. Most Pirahãs interpret this as an encounter with a spirit jaguar. For the Pirahãs, seeing spirits is a real experience conforming to the immediacy principle. Everett notes that talk of seeing spirits can seem “absurd” from a Western point of view, but he notes that “that is simply our perspective” and is really no less strange than praying to a Christian god (137).

The Pirahã divide beings into xibiisi, those with blood, and xibiisihiaba, those without blood. Xibiisihiaba, the spirits, are blond and pale skinned due to their bloodlessness, which creates doubts about whether white people are human. After working with the Pirahã for 25 years, Everett was surprised when some Pirahãs asked him if Americans die.

At night, a falsetto voice can often be heard in the jungle giving advice as a kaoáibógi spirit. One night, Everett investigated the voice and discovered a Pirahã man performing this role. The next day, the man denied knowledge of the event. Later, the Pirahãs invited Everett and Peter Gordon to see spirits. The people gathered facing the jungle, and a Pirahã man emerged dressed as a deceased woman, speaking in falsetto about being dead. He then reappeared as a comical spirit, naked and pounding the ground with a log.

Everett identifies this as theater but realizes that the Pirahãs perceive it as genuine spirit encounters. Any Pirahã man can channel spirits, and for the community, these are real, experienced events. This is why missionary efforts have failed: Religious texts like the Bible lack living eyewitnesses required by Pirahã cultural epistemology.

Joaquim was an Apurinã man living at the settlement of Ponto Sete on the Maici River. Despite facing many of the same hardships as the Pirahãs, Joaquim believed them to be inferior, thinking that his greater material wealth set him above the Pirahã. Nevertheless, Joaquim and the other Sete residents believed that they were good friends with the Pirahãs. One Pirahã village, however, considered them “inferior interlopers” with illegitimate land claims.

A feud developed between the Apurinãs and the Colário family of traders. The Apurinãs followed market prices on their shortwave radio and discovered that the Colários were cheating them. They banned the Colários from their settlement, and when Darciel Colário defied the ban, the Apurinãs opened fire on his boat. Darciel escaped injury by hiding behind his stove.

To get revenge, the Colários, who referred to all Indigenous people in the area as bichinhos (little animals), recruited Pirahã teenagers from the village of Coatá, led by Túkaaga. Darciel gave them a new shotgun to drive the Apurinãs from Sete. The Colários wanted unfettered access to jungle products, and many Pirahãs wanted the land free from competitors for fish and game.

On the fateful day, the Apurinã leader Armando and his son Tomé were upriver fishing and hunting with their wives. Only Joaquim and his Pirahã brother-in-law Otávio remained at the village. While walking home with a load of firewood, unable to look carefully from side to side, Joaquim was ambushed by Túkaaga and his friends—all teenage hunters who had never harmed a human. As Joaquim passed about 10 feet away, Túkaaga shot him in the midsection.

The blast threw Joaquin violently to the ground. Joaquim’s wife rushed to his side and tried to stop the bleeding with mud and leaves. Otávio helped move Joaquim to his hut and then paddled frantically upriver to find Tomé and Armando. Joaquim died that evening.

Around midnight, as Tomé and his wife approached Sete by canoe, someone fired at them. Tomé was blown into the river by the shot, and his wife, struck by only a few pellets, grabbed his hair and paddled to shore with an aluminum pan. Túkaaga and his friends fled to Coatá.

Armando arrived home to find Joaquim dead and Tomé severely wounded. Not knowing the attackers’ identity, the survivors fled to Coatá for protection, unknowingly seeking refuge with the families of their murderers. However, Túkaaga and his friends didn’t finish the job because they were in the village and Pirahãs could have been hurt. A trader took Tomé to the hospital in Manicoré, where he eventually recovered.

While Tomé was hospitalized, the survivors learned that the Pirahãs were their attackers and wanted them gone from the Maici. The Apurinãs had no choice but to relocate downriver, where they faced a life of indentured servitude on Brazilian settlements along the Marmelos River. Tomé swore revenge but was persuaded against it; the Pirahãs would be waiting to kill him. Within two years, most of the Apurinãs were dead.

A few months after the murder, Túkaaga was ostracized and living alone. He died under mysterious circumstances; Everett suspects that other Pirahãs killed him. The Pirahãs had become fearful after police investigated and nearby settlers considered a punitive attack; they believed that Túkaaga’s violent act had put them all at risk. His two accomplices were never punished. 

Everett explains that this story “illustrates the dark side of Pirahã culture” (148). Although generally tolerant and peaceful, the Pirahã will go to great lengths to protect their land. Furthermore, the story illustrates how difficult it is to overcome cultural barriers. Although the Apurinã had lived alongside the Pirahãs for over 50 years, they were still not accepted. Finally, the story shows how the Pirahãs punish social transgression through ostracization, thereby removing the resources of cooperation that are necessary for survival in the unforgiving jungle.

The Pirahãs face challenges from disease and incursions by outsiders—divers, fishermen, and hunters, including Japanese sport fishermen and Brazilian commercial boats on the Marmelos. These visitors pay in sugarcane rum, cloth, manioc meal, and canoes for help locating fish. Caboclos usually offer only rum to trade for food and jungle products. Rather than risking dangerous encounters, the Pirahãs often give away all their food to placate outsiders.

The Pirahãs need outside help establishing land demarcation and providing access to medicines. Everett and Keren regularly brought medicines to the villages, but Everett began to feel a strong responsibility to secure legal protection for Pirahã territory. Everett and his family traveled to the Pirahãs initially by plane, but on subsequent visits, they came to prefer boat travel, which allowed them to bring more supplies for longer stays and get to know the caboclos who lived on the river near the Pirahãs. Many would ask Everett why “those little creatures” had rights to “beautiful land” while “civilized people” do not (151). This worried Everett, who could easily imagine them trying to claim portions of Pirahã territory.

After finishing his PhD, Everett spent a year at the Massachusetts Institute of Technology (MIT) doing postdoctoral work in Noam Chomsky’s Department of Linguistics and Philosophy. Five months in, anthropologist Dr. Waud Kracke informed him that FUNAI wanted him to join an expedition to identify boundaries for an officially recognized Pirahã reservation. The invitation came from Xará, a senior FUNAI representative who had spent years traveling among the Pirahãs, Mundurucus, and Parintintins. Xará and his companion Ana wanted to guarantee that these groups could maintain their traditional way of life. Kracke and Everett were invited as interpreters.

Everett had been trying since 1979 to get officials interested in protecting Pirahã land, appealing unsuccessfully to four FUNAI directors in Porto Velho. This expedition offered the opportunity to travel the entire Maici and visit all Pirahã villages, something Everett had never done. He hired a boat in Humaitá and met up with the FUNAI team, including an anthropologist, a cartographer, and a land claims specialist, at the mouth of the Maici.

The Pirahãs greeted Everett enthusiastically. The FUNAI anthropologist, Levinho, admitted that he was initially resentful about waiting for an American but understood the necessity after three days of failed communication attempts with the Pirahãs. The team traveled up the Maici for a week, stopping at each settlement to interview inhabitants about land use.

After a week, they reached the Transamazon Highway, the end of the stretch of river where Pirahãs lived, and Everett hitchhiked back to Porto Velho. The expedition succeeded: The Pirahãs’ land was officially identified, beginning the bureaucratic process of creating a legal reservation. Levinho became fascinated by the absence of creation myths and oral history, inspiring his friend Marco Antonio Gonçalves to study Pirahã culture. Everett met nearly every living Pirahã and was invited to live in upriver villages.

Caboclos are descendants of Amazonian Indigenous peoples who now speak only Portuguese, are integrated into the regional economy, and consider themselves Brazilians rather than tribal members. The Pirahãs call them xaoói-gíi (authentic foreigners), distinguishing them from Americans and city Brazilians (simply xaoói). The Pirahãs relate better to caboclos because they share the same environment and skills of hunting, fishing, canoeing, and jungle knowledge.

Caboclo culture has intruded on the Pirahãs for over 200 years, and the Pirahãs’ knowledge of the outside world comes almost exclusively from caboclo contact. Caboclos have a “macho culture” with an aspect of stoicism bordering on fatalism. They believe that hard work signals “health, good character, and stewardship of God’s blessings” (159), while excess body fat and laziness signal corruption. Even wealthy caboclos maintain a strong work ethic, clearing their own fields alongside employees. These values—leanness, toughness, jungle knowledge, hunting, fishing, and self-reliance—are shared to some degree by the Pirahãs. In order to understand how the Pirahãs saw outsiders, and therefore himself, Everett knew he had to get to know the caboclos to some degree. 

Everett mostly interacted with caboclos during his numerous trips up and down the river. He recounts one river trip taking a dentist and his cousin to visit the Pirahãs. At the Porto Velho dock, he hired a large, new-looking boat whose owner promised a five o’clock departure. However, following delays in loading cargo, they couldn’t leave until the next morning. In the afternoon, the inexperienced crew ran aground on a sandbar for 24 hours.

On another trip, a woman at the settlement of Pau Queimado flagged down Everett’s boat. Her father, a respected master canoe maker and devout Christian called Seu Alfredo, was gravely ill. Everett found Alfredo on his deathbed in great pain. However, Alfredo refused hospital transport; he knew he was dying and expressed peace and gratitude for his life, saying that he was unafraid because of his faith in Jesus. Everett was profoundly moved, witnessing a fearless acceptance of death unlike anything he had seen before or since. The caboclos live according to the “code of the Amazon” (165): They always help others in need because they may be the person who needs help the next time. Any house along the river can be a haven. That family will aid you, shelter you, feed you, and paddle you to help if needed.

However, Everett is still perplexed by caboclo racism against Indigenous people. Caboclos tell Everett that “they are Indians who learned to work” (166), and they believe that communities like the Pirahãs are “lazy” and “beg” for help. Ironically, caboclos refer to themselves as ribeirinhos (river dwellers) or simply Brazilians; they call the Indigenous people in the area “caboclos” and are often the only ones who know if there are uncontacted tribes in the area. They don’t consider Indigenous speech real language; all Indigenous languages seem the same to them. To find uncontacted tribes, one must ask about caboclos who can “cut the slang” (166).

Caboclos “feel their poverty desperately” (166), unlike the Pirahãs, who lack a concept of “poor” and are satisfied materially. During the 1980s gold rush on the Madeira, caboclos risked their lives as untrained divers, descending 50 feet in pitch-black, fast-moving water with anacondas, caimans, and stingrays, holding vacuum hoses on the riverbed. Sometimes rival barges would murder crews and cut divers’ air hoses if they found gold to claim it for their own. Despite the danger, the caboclos who struck gold claimed that the risks were worthwhile. 

Caboclo humor is distinctive. One newly rich prospector walked Porto Velho’s streets with money tied behind his back, explaining that he had spent his life chasing money; now, money could chase him. Another example occurred in Humaitá’s plaza one evening. A little boy asked his grandmother for a Coca-Cola; she refused. He ran to his father, who suggested that they kill the grandmother. Horrified, the boy protested. His father chuckled and returned to work.

Caboclo supernatural beliefs—an amalgam of Catholicism, Indigenous myths, and African spiritism (macumba)—strongly influence the Pirahãs. These include the curupira (a jungle elf with backward-pointing feet who leads people deeper into the jungle) and pink river dolphins that transform into men to seduce virgins. 

Everett became friends with Godofredo Monteiro, the caboclo river trader who helped Everett when Shannon and Keren were ill. Godofredo had two daughters, Sônia and Regina. At age 12, Sônia and a friend died suddenly with terrible abdominal cramps. Godofredo’s diagnosis was that she “mixed her fruits” (171), a common caboclo food superstition. When his son Juarez had malaria, Godofredo refused medical help, arguing that doctors don’t control death and that even doctors die. Years later, Everett offered to pay for Juarez to train as a radio technician in Porto Velho with an American friend. Godofredo refused, holding the caboclo belief that his children were his economic assets; if his son learned a trade in the city, he would no longer be available for work for his father. Everett was surprised and angered by this decision, believing it to be selfish. Juarez became a diver during the gold rush, making enough money to pay family debts, buy a house, and start an ice-cream stand, but he was later killed in a motorcycle accident on the Transamazon Highway.

Caboclos live by a code of honor: They will not tolerate being wronged, insulted, or physically touched, and they treat others with the same respect. They will help if asked but are highly sensitive to slights. Sometimes Everett’s white skin and foreignness threatened offense because many Brazilians believe that Americans are racist and feel superior. Once, an enormous logging boat moored near Everett’s house, and the crew of 35 intimidating men stared at Keren and his daughters. Everett, though outmatched, boarded and demanded that they leave Pirahã land. The owner, Romano, initially challenged him but eventually ordered his crew to prepare to leave. He offered Everett coffee before departing politely.

Caboclos are isolated even from other Brazilians, something that the Pirahãs notice when other Brazilians or foreigners come onto their land. This became clear when college students from São Paulo visited, and caboclos told Everett that foreigners who “spoke Portuguese poorly just like [him]” had been there (174). The “foreigners” were Brazilians from São Paulo. To caboclos, an American gringo and a Brazilian from the South are both foreign.