So Chomsky's theory, which currently holds true, is that only human beings can learn and use language. Don't be confused by this: plenty of animals communicate. Language is much more than communication. Language has structure, grammatical rules, is affected by culture, and so much more. Animal communication may have one of these elements but as far as we know there are absolutely no animals that can use language or have ever used language; it is simply not something that can be taught to them. A few animals can mimic elements of language but they don't really use it in any meaningful sense. They simply imitate and repeat and cannot interchange vocabulary to form new grammatically correct sentences and so on. There are many who have tried, such as teaching Koko the gorilla sign language, but ultimately have failed.

Additionally, Chomsky says that because language is so ingrained into the human condition and we have literally evolved to use it, we don't even have to "learn" it in the traditional sense. Language is acquired by human beings. We simply pick it up by hearing it. We don't just pick up on the words, we pick up on the grammar, the idiosyncrasies, the exceptions to the grammar, the whole of it. This method of learning second and third languages is a concept that has really taken off in language learning communities in the past 20 years: the language acquisition method. So he kind of has a point here. Animals we have attempted to get to use language (and have failed) we have tried desperately to teach them. They simply cannot nor have ever acquired language. So we can't teach it to them and they can't acquire it despite half a century of people trying to prove Chomsky wrong.