Sorry but I know a fair amount about your claim about apes and sign language. They never, ever, learned "complex sign language from us as quick as a dog learns to sit." They learned some signs. And, when taught young, they used the signs for life, pretty much. That has NOTHING TO DO with learning to sign like people do.

You missed the point. Read the referenced article. The big point was that some of us believe Chomsky was right that human natural language evolved, creating the first humans, in an evolutionary instant. Technically it is a specialization of hierarchical serialization/deserialization computations in animal perception and action to be able to express information about what the other parts of the brain are 'thinking' in particular expressive ways (read about grammar and semantics), associated with Wernicke / Broca areas -- that do NOT exist as brain organs in Chimps.

No chimp ever just tried signing after watching people do it. Just like they never started to try to talk (make human speech noises to learn to speak). The kind of communication that people can achieve among each other is just lost on the chimp. It ain't there. This does not mean they do not think, remember, and otherwise reason like we do. What they lack is the ability to *communicate* the information details of it among members of their species like we do with human natural language.

What was said about speech (muscles, shapes of cavities, ennervation, etc) was that the ultimate refinement we see in humans was really driven by (this quick) natural language evolution. Not vice versa. There is plenty of evidence for that.