Read the article in the New Yorker . The article is not just about Everette.  Fitch and Sheldon and others have been looking into this.  Read the experiment of the bouncing monkey's head.  Also, these pirahans are not very cooperative. They are not like monkeys or dogs in allowing themselves to be examined, and even have taken an impish approach to trying to screw up the experiments.   My hunch is that if some of these people were to be adopted into a USA setting, and brought up watching Sesame Street, etc --that they would develop recursive language, but when they start in at elementary school, they will not catch on nearly as fast as even Mexican or negro children do, Remember that Americanized children of mulattoes,negroes and hispanic mestizoes, themselves, lag far far behind Chinese and caucasians.  I doubt though, that the Brazilian gubment would allow any such adoption  &amp; experimentation, since these Pirahans are sort of endangered. My thoughts exactly, I read through the whole article (long but interesting), it seemed to me that neither the field linguists nor the theoretical ones have deciphered the language yet.    I found interesting what they explain about recursion, they even mentioned that some African tribes didn't have it in their native tongues but were able to learn a western language that does, which brings me to the point, sure you can teach some primitive peoples how to speak European tongues, but do they actually understand its deepness? do they really grasp things like recursion?    If you take a look at how non-whites butcher and bastardize every European language they were thought, how, if left on their own, the language use declines into simple phrases and slang terms, let's take ebonics for example, doesn't it strike a resemblance on how they explained the Piranhã language used simple non-recursive phrases centered around what's immediately seen or known? doesn't that particular aspect of the culture also strike resemblances to the non-whites immediate gratification and living by the minute and no planning for the future racial traits?    I'm just saying the whole Piranhã philosophy of life struck me as the core principles on the huge majority of non-whites I've met, and the Piranhã being anti-change and refusing anything foreign, I see them as a window into what the non-white peoples would really be without our influence or what they could degenerate to if deprived from our influence.