“It was about 5:45 p.m., the most beautiful time of day, when the sun glows orange and the river’s reflective darkness stands out against the rusty color of the sky and the luxuriant spinach green of the jungle. As I sat idly watching and sipping my coffee, I was startled by the sight of two small gray porpoises jumping in sync out of the river....Almost immediately, from around the bend came two Pirahã canoes, their riders paddling for all they were worth, in pursuit of the porpoises, trying to touch them with their paddles. It was a game of tag, porpoise tag.”

The early and descriptive passages of Daniel L. Everett’s book, “Don’t Sleep, There are Snakes,” a work chronicling his life with and research on the Pirahã, paint a picture of a near-idyllic retreat. However, the response the work has provoked at home—particularly within the linguistic community—has been far from tranquil. And while Everett and this book are gaining national attention for the unique nature of his discoveries, he’s also raising quite a few eyebrows in the world of academia.

The Pirahã are a small tribe of Amazonian indigenous people who dwell on the banks of the Maici River, a tributary of the Madeira River in Northwest Brazil. Though they have some contact with the outside world through traders on the river, they speak a very inaccessible, tonal language, and apparently haven’t changed much since the first European explorers encountered them well over two centuries ago. They live on a day-by-day basis, catching only what food they need and leaving little behind by way of art, jewelry, possessions, or material goods. Nevertheless, Everett describes them as both “firmly committed to the pragmatic concept of utility” and some of the happiest people he has ever known—unsettlingly echoing the colonialist stereotype of the ignorant but blissful savage.

Most of the first part of “Don’t Sleep” is concerned with recounting the author’s more memorable experiences. Everett, who has spent much of the past 30 years living among and studying the Pirahã, relates a number of vignettes about his time with the people. He gives some colorful background about how he started this work—he began as a missionary, trying to translate the Bible for the Pirahã. He tells us with off-putting honesty about his family’s near-fatal brush with malaria, and how his own ignorance almost killed them. He divulges touching but insightful tales about the Pirahã, allowing the reader both a better glimpse of the scarcely tenable culture and provoking a chuckle, or a pang of empathy. His anecdotes exude an exotic mystique, generating a certain sense of fantasy. One wonder how can such a people, such a place exist?

Take Everett’s story of his brush with a giant anaconda. After he veers his small boat, laden with his family, out of the beast’s path he manages to just catch it with his propeller. “Then a second later the entire snake’s body stood up out of the water, towering above the boat....I looked at the entire length of the snake’s whitish underbelly as it fell backward with a loud, large splash into the Madeira River.”

But, “Don’t Sleep, There Are Snakes” provides more than just a glimpse of what Everett’s life with the Pirahã was like. Though he does spin a number of colorful but disparate narrative threads, the cross-stitch that binds them all together is his research. In fact, the whole second part of the book is geared toward explaining many of the findings that have helped Everett make a name for himself in the academic world (though much of this bubbles up in the former part of the text as well).

According to Everett—who has spent more time with the Pirahã than any other researcher and is the authority on their language—the Pirahã lack counting and numbers, creation myths, an kinesthetically-oriented sense of direction, and even some linguistic attributes that were commonly held to be universal. These include quantifiers (e.g. all, every) and recursion (the placement of one phrase or sentence within another).

Everett harps on what the Pirahã lack in comparison to Western culture. This labor, however, pays off in that it allows the casual reader to gain a basic understanding of the gravity of his assertions and of some fairly complex linguistic concepts to boot. Everett provides basic explanations of theories in the field such as the theory of universal grammar (which asserts that there are grammatical principles innately common to all living humans) and Hockett’s “duality of patterning” tool, stemming from a list of theoretical language universals. Yet he does so mostly to advance his own theory about why the Pirahã have not adapted as the surrounding peoples have.

The author tries to assert—at times more successfully than others—that the Pirahã do not lack numbers or other seemingly integral cultural and linguistic components because they are in some way more primitive or less human than Westerners, but rather because their language has been shaped by their culture.

The bulwark supporting this argument is Everett’s Immediacy of Experience Principle, which can be summarized (with some liberty) as the idea that the Pirahã do not speak about anything outside the realm of their own immediate experience or that of someone who is alive within the speaker’s lifetime. This assertion itself is said to predict the aforementioned linguistic deficiencies, and through its implications, to defy some of the most basic tenets of the linguistics world. And here is where the road gets rocky.

Everett’s claims fly in the face of some of the most basic and established beliefs in the fields of psychology and linguistics. The author even targets some of the biggest names in these fields—many of them right here at Harvard—like MIT Professor Noam Chomsky, Harvard Psychology professors Steven Pinker and Marc D. Hauser, and rising Linguistics star Andrew I. Nevins.

Nevins, an assistant professor in the Linguistics department has come out most strongly against Everett’s arguments, co-writing a paper refuting the validity of almost every point Everett makes about the extraordinary nature of the Pirahã language (“Pirahã Exceptionality: a Reassessment”). Nevins and his co-authors outright repudiate Everett’s claims about the absence of embedding—which includes, among other things, the use of relative clauses—in Pirahã. The critics also draw parallels to other cultures in realms where Everett argues the Pirahã are unique, such as in the absence of color terms, and the absence of a numbers and quantification. The strength of these repudiations lies in the fact that they primarily rely on Everett’s own previously published work on Pirahã language and grammar to dispute his claims.

Nevins and company also draw attention to other, equally serious concerns about the characterization of the Pirahã people. “Given the inevitable impression left when one describes a people primarily in terms of what they lack, we would expect this sort of characterization would be offered only as a last resort—and on the basis of the firmest possible evidence. We have argued that in the present instance, the evidence is anything but firm. Hence our discomfort.” Professor Pinker, on the other hand, sees some merit in Everett’s work “and believe[s] that linguists should take his criticisms of the field seriously,” but he also fundamentally disagrees with Everett’s conclusions.

Everett addresses these dissenting opinions throughout “Don’t Sleep, There Are Snakes” with a voice that is sometimes conciliatory, more often bullish, but always attuned. And while he argues his points convincingly and in very straightforward terms, it is important to remember that this is a debate that is far from over. “Don’t Sleep, There Are Snakes” is just one side of this dispute over our basic understandings of human linguistics and grammar. It is part of a larger dialogue, and an attempt perhaps to broaden that dialogue and bring it into the homes and minds of more than just the hyper-educated elite. Luckily for Everett, the combination of his powerful assertions, the inherently exotic nature of his subject matter (which has already drawn much media attention), and his accessible and authoritative writing style, may do just that for his theories.

—Reviewer Joshua J. Kearney can be reached at kearney@fas.harvard.edu.