In the case of Gorilla, I think it wasn't quite the level of sign language that it learned, but vocabularies and phrases.
I had a psychology professor who was part of the research teaching Koko sign language. And according to him, what Koko learned was really impressive, more than they anticipated. But it was still fundamentally different from human language.
It was a long time ago, and I don't recall what exactly was lacking. It could be on the lines of grammatical structures, that for Koko, there was no difference between "not want banana" and "want banana not". She didn't have an idea of what the negation was directed at. In the eye of linguistic psycholinguistics, the difference wasn't trivial.
In contrast, human children, even with limited vocabulary, could grasp and even invent grammars.
> In contrast, human children, even with limited vocabulary, could grasp and even invent grammars.
The most prominent example would be Nicaraguan Sign Language, which was spontaneously invented over only a few years by deaf schoolchildren, ages four to sixteen, who had little or no other language.
The science isn't there for gorillas communicating like humans. No publications, no data and Robin Williams anecdotes instead. If there was something there one would think there would be more scientists doing research down that path.
I had a psychology professor who was part of the research teaching Koko sign language. And according to him, what Koko learned was really impressive, more than they anticipated. But it was still fundamentally different from human language.
It was a long time ago, and I don't recall what exactly was lacking. It could be on the lines of grammatical structures, that for Koko, there was no difference between "not want banana" and "want banana not". She didn't have an idea of what the negation was directed at. In the eye of linguistic psycholinguistics, the difference wasn't trivial.
In contrast, human children, even with limited vocabulary, could grasp and even invent grammars.