What do all languages have in common?

Language is endlessly variable. Each of us can come up with an infinite number of sentences in our native language, and we're able to do so from an early age— almost as soon as we start to communicate in sentences. How is this possible? In the early 1950s, Noam Chomsky proposed a theory that the key to this versatility was grammar. Cameron Morin details Chomsky's theory of universal grammar. [Directed by Eoin Duffy, narrated by Addison Anderson, music by Sono Sanctus].