Edge has an interesting video of linguist Daniel Everett discussing his ideas of recursion in human language and thought.
The current, Chomskyan view of language is that we are basically pre-wired by our genes with the ability to produce infinite grammars using finite structures. In other words, we have no limit to what we can say even though we have a limited vocabulary. This ability is triggered and shaped by our environment and is also a function of our ability to use recursion. Recursion is the ability to insert a phrase into another phrase of the same type. Here's an example that Everett gives:
"If I say 'John's brother's house', I have a noun, 'house', which occurs in a noun phrase, 'brother's house', and that noun phrase occurs in another noun phrase, 'John's brother's house'."
Essentially, one could infinitely add on additional phrases to any sentence. (John's brother's house; John's brother's sister's house; John's brother's sister's husband's house, etc.) Recursion is supposed to be the fundamental property of human language. But what happens if you find a language that doesn't use recursion? Well it would go against the ideas of Chomsky and instead put forward the proposition that humans do not need a universal grammar. And this is what Everett is, in fact, claiming.
He is claiming that a culture from the Amazon, the Piraha, of which he has worked with for 30 years, do not exhibit recursion in their language. If this is so, then that means the Piraha are limited in what they can say, though that doesn't mean their language is not a rich one. This would be considerable evidence against the Chomskyan paradigm. It would mean that recursion isn't an essential element to human language. But he doesn't go so far as saying that recursion is unimportant:
"If you go back to the Pirahã language, and you look at the stories that they tell, you do find recursion. You find that ideas are built inside of other ideas, and one part of the story is subordinate to another part of the story. That's not part of the grammar per se, that's part of the way that they tell their stories. So my idea is that recursion is absolutely essential to the human brain, and it's a part of the fact that humans have larger brains than other species. In fact, one of the papers at the recursion conference was on recursion in other species, and it talked about how when deer look for food in the forest, they often use recursive strategies to map their way across the forest and back, and take little side paths that can be analyzed as recursive paths. So it's not clear, first of all that recursion is unique to humans, and it's certainly not clear that recursion is part of language as opposed to part of the brain's general processing."
His idea seems to be that recursion is a property of the human brain in general, as well language is also a property of our brains. We don't necessarily have to have a "language instinct." And instead, it's possible that language is just a product of our ability to use our greater general intelligence as compared with other species to solve our everyday problems. It's an interesting idea, though a lot of research would have to be done and scrutinized before such controversial claims could be verified. Well, anyways, check out the video. There's also a transcription of the interview here. As well, there are also some really good responses and counter-responses to Everett here, including a response from Steven Pinker, which is pretty cool. Check them out!