Deep in the Amazon rainforest of Brazil, linguists are trying unravel the structure of a tribal language that might be radically different than any other.
Only a few hundred people are members of the tribe, known as the Piraha, who speak a language of the same name. They've resolutely avoided any cultural dilution whatsoever, including learning Portuguese.
This means that cross-language comparisons with Piraha have been extraordinarily difficult - until now.
Researchers from MIT, in collaboration with the linguist Daniel Everett (one of the few non-native Piraha speakers in the world) have released a study based on the largest collection of Piraha sentences ever complied to date.
They found support for one of the most controversial claims about the language - the idea that it might lack a feature known as recursion that's long been considered a basic principle of all languages.
The researchers emphasized that this conclusion is "highly tentative" at this early stage. But if the new finding holds up, we'll need to shift our thinking on not only how language works, but how it developed in the first place.
It would be a huge blow to Noam Chomsky's famous (and controversial) theory of a "universal grammar" that developed because of the human brain and serves as the basis for all languages.
Why recursion matters
Recursion is how languages build in flexibility; it lets us nest sentences (and clauses) inside of each other. A key feature is that there's no limit to how long a sentence can get. If you and I got into a competition about who could speak the longest English sentence, no one would win - ever.
I wrote this article.
She says I wrote this article.
He thinks she says I wrote this article.
And so on, until we both die.
A classic example of recursion is this potentially neverending children's story:
This is the house that Jack built.
This is the malt that lay in the house that Jack built.
This is the rat that ate the malt that lay in the house that Jack built.
This might not seem very significant. But linguists have been grappling for decades with what exactly defines a language, and if there are any features that they all share. That's why recursion is special. By most accounts, every single known language does this - with the possible exception of Piraha.
A language unlike any other
This isn't the first time Piraha has presented challenges to the field of linguistics.
In 2008, a different MIT study showed that the tribe has a profoundly differently approach to numbers: All counting in Piraha is relative. There are no words for specific quantities like "one" or "two," just "a few" and "more."
Some of linguists, however, treat Everett's work with skepticism.
For a long time, his research was more or less the only body of work on the Piraha, and he made some pretty incredible claims - including that the tribe doesn't make art or have fixed words for specific colors. Everett first suggested that Piraha might not have recursion at least ten years ago, but the new dataset offers some concrete - if not conclusive - evidence.
"We think [the new dataset is] consistent with there being no recursion, but we can't say for sure," Edward Gibson, a coauthor of the new paper and a cognitive scientist at MIT, said in a press release. "It's plausible."
The new data included 1,100 translated sentences; they'll need many more to firm up their hypothesis. Other researchers are starting to delve into fieldwork with the Piraha people and have come to a different conclusions about whether or not the language has recursion.
Piraha, while certainly one of the most isolated languages in the world, is hardly the only linguistic enigma researchers are working to crack before its speakers disappear forever.
To listen to an interview with a man speaking Piraha, check out this YouTube video.