A long article (and a fairly old one too) about the Pirahã people of the Amazon.
Daniel Everett, who has studied the Pirahã over many years, believes their language contradicts the Chomskyan paradigm of universal linguistic structures. They do not count with numerals, and have difficulty in distinguishing groups of objects where the number exceeds two. This is not, the New Yorker writer notes, down to 'mass retardation'. They appear not to have words for colours. They lack any signs of a belief in God, or even a creation myth. Their pronoun system, which is rudimentary, may have been a borrowing from a neighbouring Amazonian language, before which they may have had no pronouns whatever. They have no words for right or left. Their language does not demonstrate one of the most basic Chomskyan features of all, recursion, or the ability to embed clauses (Wikipedia's example: 'Dorothy, who met the wicked Witch of the West in Munchkin Land where her wicked Witch sister was killed, liquidated her with a pail of water.')
For an outsider, their referential framework can seem impossible to crack. From the article linked above:
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.”
They appear to be almost fundamentalist in their experientialism:
Committed to an existence in which only observable experience is real, the Pirahã do not think, or speak, in abstractions—and thus do not use color terms, quantifiers, numbers, or myths. Everett pointed to the word xibipío as a clue to how the Pirahã perceive reality solely according to what exists within the boundaries of their direct experience—which Everett defined as anything that they can see and hear, or that someone living has seen and heard. “When someone walks around a bend in the river, the Pirahã say that the person has not simply gone away but xibipío—‘gone out of experience,’ ” Everett said. “They use the same phrase when a candle flame flickers. The light ‘goes in and out of experience.’ ”
Their phonemes are extremely difficult to master. When Everett discovered that their language uses a voiceless dental bilabially trilled affricate (exhausting just to write that down, never mind try pronouncing one) he wondered whether they had never used the sound in his presence before because they were 'ridiculed' when they did so in front of non-Pirahã.
Fewer than four hundred Pirahã survive, which suggests they may soon be going 'out of experience'.