A few hundred years wouldn't evolve a species out of the ability to use language. Language isn't cultural. If you take a dozen babies from different cultures/language communities, and cut off their tongues, and if their caregivers never speak to them, they will still find a way to use a pidgin language among themselves, because human language is innate.
Language is very much cultural, the instinct to communicate and decipher others utterances is what is inate. Otherwise one could automatically understand other languages without learning them.
Dolphins and whales are already communicating currently. But it's possible that what we are seeing now is a much simpler version of what existed previously, not to mention that we don't have any clue how to decipher what we are hearing now.
