I'm sure chimps would be able to speak human languages, at least in a slow and limited fashion, if they had the right vocal apparatus. They can learn sign language, after all. In fact, many domestic animals - dogs and pigs, certainly - may well understand more of our speech than we give them credit for, although not the higher theoretical concepts. I am not saying that they will inevitably develop complex languages of their own, in the course of future evolution. It would only happen if selective survival favoured it overwhelmingly.