There is much to agree with in Sue Savage-Rumbaugh's reflections on human and nonhuman primates. Sue has probably spent more real time rearing and observing our closest hominoid cousins than any other human being has done. Bonobos are indeed astonishingly intelligent and capable, and become still more human-like when reared in daily contact with humans.
But there is one radical inference Sue makes that it will be hard for most people to agree with: Bonobos have acquired a ("kind of") language: "the kind of language they have acquired — even if they have not manifested all major components yet — is human language as you and I speak it and know it."
Let us reflect for a moment on languages and kinds: Humans have many kinds of languages, but there is one thing all those languages have in common: Anything you can say in one of them, you can say in any of the others. And anything and everything that can be said at all can be said in any one of them. Not necessarily in the same number of words (and you might have to define a few new ones); not necessarily equally elegantly; but anything and everything.
(Some readers may find the foregoing assertion as hard to agree with as Sue's that bonobos have language. I suggest they test their intuitions by finding a counter-example: either a human language in which you can say this, but not that; or something you cannot say in any human language. Until someone comes up with such a counter-example, I will provisionally take it to be a true property of language -- not human language, but language itself -- that if you have it, you can say anything and everything that can be said [or gestured or written, as the modality need not, of course, be vocal], and if not, not.)
Neither Kanzi nor his kin or kind can say everything (or anything faintly near everything). I accordingly conclude that they cannot say anything. They can do a lot -- far more than anyone ever imagined nonhuman primates could do. And what they can do includes an astonishing amount of intelligent, purposive communication with humans, using some of the same components to communicate that humans use for language: They can communicate purposively by sending and receiving computer images as well as by responding to human spoken sounds. But the undeniable fact is that -- no matter how much linguistic understanding we attribute to them -- they cannot enter into this "conversation" we are having in this Forum, not even into a rudimentary approximation to it, whereas any speaking human being, using any (spoken or gestural or written) language, can; even a child.
And the most likely reason for that is that bonobos cannot express or understand propositions as propositions (statements with a truth-value: true or false), otherwise they could express and understand any and every proposition; and what they do understand and express when we think they are understanding propositions is not what we think it is. The "narrative" gloss that we project on it is more like the sound-track of a silent movie -- one generated by our own language-prepared brains, irresistibly "narratizing" (as Julian Jaynes dubbed it) every scene we see, but especially every communicative interaction with another mind (and sometimes even, frustrated, with malfunctioning machines). We are inadvertently projecting propositionality even where it is absent.
(This is not merely about "aboutness" in the sense Sue intends it -- not just about the intended object or "referent" of attention, shared attention, pointing, gesturing, or miming; it is about making and meaning subject/predicate assertions with truth values. For that is what gives language its unbounded expressive power, allowing us to express any and every proposition. Nor does that have anything to do with "consciousness," i.e., feelings, which bonobos, and of course most -- probably all -- animals have; nor with the "self/other" distinction, which many species can make, to varying degrees, in the practical, sensorimotor sense, but none but ourselves can make in the linguistic sense.)
It is hard to understand why creatures as stunningly intelligent and capable as bonobos cannot acquire language. I'd say that that inability was a more remarkable and puzzling fact -- begging to be understood and explained -- than even the remarkable intellectual and communicative feats that bononbos have indeed proved capable of mastering; for of course it is precisely how very much they can do that makes what they can't do all the more perplexing: Why can't they say anything and everything, given what they can demonstrably do, if it's really language?
Sue's reply is: "cultural differences"; and with Teco she's hoping to close the cultural gap. But with any human child, the gap is closed almost immediately, in infancy, once the child acquires (any) natural language. (Some unnatural languages can be designed that defy the child's language-learning capacities, but that's another matter; even those artificial languages still have the full expressive power of any natural language.)
So until Teco can join this conversation, I will assume that what is going on is a good deal of hopeful, irresistible propositional over-interpretation (by humans) of some remarkable cognitive and communicative capabilities and performance (by bonobos) -- but not a conversation, not propositions, and hence not language.