It’s probably true to say that Pirahã is the most controversial language in the world owing to Daniel Everett arguing that the language doesn’t have recursion, as Chomsky’s ‘universal’ language theory predicts, and doesn’t have fixed words for numbers or colours.
New Scientist has just put a video online that is a superbrief introduction to Everett’s theory, but best of all, we get to hear the language spoken.
Everett is also interviewed in this week’s issue of the science magazine, but it’s behind a pay wall, so I’d just read it in the newsagent.
However, if you want more detail over the controversy, it’s been well covered in other places.
Link to brief video of Everett at work.