"makes grammatical mistakes." writes Wittgenstein (PI, s. 67). But, as Geary notes, few other animals speak, to start with. I'm collecting dicta on "man is the only animal that ..." -- the point: to illustrate Aristotle's idea of the "idion". Man is the only animal that wipes his arse. Man is the only animal that writes and reads pornography. Etc. J. L. S. Bordighera