Native speakers of Pirahã, in the Amazon lowland jungle, have no words for left or right, they use the same term for blue and green, and their definitions of red, black and white turn out to be similes, rather than dedicated words.
These once-isolated people, a tiny group, have no system of numbers; their sentences cannot accommodate subordinate clauses or other forms of recursion (embedding phrases), and they are not impressed by the Gospel of St Mark in Pirahã, not least because it is a story composed by someone they do not know, about someone they have never heard of, in a time and place that has no meaning for them. The Pirahã people tend to confine their discourse to things they know about, and their verb forms can be suffixed to distinguish between hearsay, inference and observation. They have no perfect tense.
On the other hand, they can also sing, hum, yell and whistle information to one another. So they have four additional speech forms and a precise vocabulary for their environment and everything in it that matters to them. If there is some deep structure that underpins all 7,000 human languages — a universal grammar or language acquisition device or language instinct, already hard-wired in the human brain at birth — Pirahã seems to be an exception.
For Daniel Everett — linguist, anthropologist and once an evangelist missionary in the Amazon — the case settles an old argument about the nature of language. The exceptional language of the Pirahã people seems to be a unique cultural tool — such as their knowledge of plant toxins, and their ability to fish with a bow and arrow — adapted for their exceptional circumstances. It is just another finely honed instrument from the human cognitive toolbox: we have large brains, we are social animals, we cooperate, we have a lucky arrangement of lungs, larynx, pharynx, palate, tongue, teeth and lips. We can speak, and so language has evolved, just as our brains and bipedal locomotion have evolved.
Language, in the Everett formula, is the sum of cognition plus culture plus communication. There is no need for a language instinct to set a three-year-old talking nineteen to the dozen. The infant's ambient culture compels the order of subject, verb and object, the potency of individual words and phrases (such as "nineteen to the dozen"), and the precise choice of phonemes.
This claim has reportedly annoyed other linguists, among them Noam Chomsky, the founder of the belief in what, for shorthand, is called a universal grammar. It also presents a challenge to the arguments of the psychologist Steven Pinker, author of The Language Instinct, a 1994 bestseller. The notion of language as an innate human talent received a colossal fillip that year with the identification of one British family, some of whose members, through three generations, were perfectly ordinary, while others had a very precise and puzzling problem with the rules of language. This was interpreted as evidence for a "grammar gene".
This was before the genome of even the simplest bacterial organism had been sequenced, during an era in which researchers were betting that humans inherited more than 100,000 genes, perhaps even a million.
The picture has changed since the human genome project ended in 2003. The awesome bundle of human complexity turned out to be delivered by about 23,000 genes; many more than a fruit fly, certainly, but many fewer than the maize plant. Whatever it is that lets us relish the preposterous loquacity of Mr Micawber, condemn the hubris of footballers and compile scenarios for a Greek debt default, all on a brief bus ride, it won't be a simple genetic turn of the screw in a larger than usual primate brain.
But beyond that lies another difficulty: arguments about what the shape and capacity of a language tells us are difficult to follow.
There is another reason for confusion. Everett — once part of a Texas rock band, before he became a trainee missionary — is the kind of scholar often described as "flamboyant".
He has not, however, written a flamboyant book. At places, he wades into academic discourse as an Amazon traveller might wade through a lagoon in the rainy season, stirring up more mud than clarity. "More ordered thoughts and communication would have been facilitated in a beneficent cycle of evolutionary improvement," he says, in a passage I don't suppose he could translate into Pirahã.
Fewer words might have forced more pointed argument. That said, most of it is revelatory. There is nothing about humans that is quite as astonishing as language.
Persevere through disciplinary defensiveness and the components of language become clearer: a theory of mind, intentionality, contingent judgment, a lot of cultural expectation and some biology that makes possible not just the usual vowels and consonants but also words made up of clicks, glottal stops, plosives and the voiceless dental bilabially trilled affricate (rare, even in the Amazon). As a bonus, you will also learn why you shouldn't talk with your mouth full.
Tim Radford's The Address Book has been published by Fourth Estate.
Language: The Cultural Tool By Daniel Everett,Profile Books, 320 pages, £14.99