I am definitely not trying to go through all the problems that such a study sets without solving the crucial one.
I have already commented ad nauseam on the different "objects" that the unique English word LANGUAGE seems to point to ("objects" covered more accurately by the three Spanish terms LENGUAJE, LENGUA and IDIOMA), so that it is not at all clear what "object" are the researchers trying to discover in apes, but… oh well!).
It seems almost a truism that some sort of coded material is active in several (if not all) communication processes of other non-human species. Humans did not invent codes ex nihilo; there have to be examples of it in other species. This is a logical thought for an evolutionist.
It is a silly truism to say that coded material of apes (and other species) has semantics aspects in it, for that is exactly what coding does.
The crucial problem when comparing human communication to other species communicative acts, seems to be the fact that there is a semantic meaning in the coded material we use, but alongside it, and well differentiated, we manage to convey what some call speaker’s meaning (or pragmatic meaning, or import, or sense, or whatever) which is really the goal of our communicative acts.
A real interesting research for me would be to find out whether some species manage that communicative achievement, not to insist yet again and again that some species have codes, some learn them by experience, and so on. This is what Germans would call “cold coffee” (kalter Kaffee), or what Mullah Nasrudin attempted, looking for his lost key under the lighted lantern in the street, a few yards away of where he had lost it which was too dark to explore!
