The Big Question: How Did Language Evolve? -- I

The other day, a philosopher I have known for many years and I got into a debate as to how languages evolved. His view is that we are the products of evolutionary processes (which I accept as true) and therefore we should expect to find evidence of some level of linguistic competence in other mammals, including especially apes (something I believe is problematic if pushed too far). The next day, I happened upon a item referring to a Bonobo's (one of the types of chimpanzees closest to humans genetically) having pulled a fire alarm because she was tired of waiting for her tenders let her outdoors. Perhaps I am being a bit dim, but it is difficult for me to see how the Bonobos' setting off a fire alarm is all that newsworthy since dogs evidence similar methods of communication when they want to be let in or let out of our homes (by scratching the door, barking at the door, ringing a bell attached to the door knob, as well as other dazzling tricks). What grabbed my attention is that in the original Associated Press story I found this remarkable claim:

Bonobos are one of the most human-like of the great apes and have sophisticated language skills.

Ah, "sophisticated language skills." Give me a break. Bonobos may have "sophisticated communication skills," but that is very far from saying that they have "sophisticated language skills."

This is a journalist's claim, not a scholar's claim but it illustrates the problem we face in discussing the evolution of language. We must first make clear that we are talking about language, not communication, something which clearly is possible in the absence of language. The problem with this is that some are willing to take damn near any signaling system found in nature as an instance of linguistic communication. Compare what Ula Hedeager says about language

Birdsong appears to have much in common with human language.

with what John Limber says

An organism uses human language if and only if it uses structures characteristic of those languages.

You will perhaps not be surprised to learn I side with Limber.

The fact is that human languages are extremely complex. I entered into the third class of linguistic students at MIT in 1963 and from then til now not only has no language been exhaustively described, linguists are not agreed as to how to go about describing sentence structure of languages. Empirically sound, mathematically based descriptions of language are very difficult to come by.

Nevertheless, some minimum requirements a putative language must satisfy can be established. It should, for instance, exhibit a capacity for dealing with what we call "grammatical relations." The most basic grammatical relations are those that hold between subjects and predicates and verbs and their objects. In English we have sentences like

1. John loves that girl.
2. That girl loves John.
3. That girl, John loves.

We have three sentences here containing the same words/symbols but three different word orders. We know that in any circumstance in which 1 is true, 3 will be true and from this we may conclude that they have the same conventional meaning despite the striking difference in word order, a difference that we use to signal secondary meaning (emphasis, perhaps). [It is not uncommon for a set of sentences with the same conventional meaning to vary in secondary meaning or significance -- in this case, the speaker implicates that this girl is the only one of a set of girls that John likes.] On the other hand, 1 can be true when 2 is false and because of that we must conclude that they differ in conventional meaning.

One can complicate this problem a bit by introducing pairs like

4. Barry told Sam that {John likes that girl}.

Here we have something closely resembling a sentence (number 1 above) being embedded inside another sentence. This device of embedding is one of the devices we exploit to create what Chomsky famously called "novel sentences." The braces here illustrate the fact that the sentences of human languages exhibit hierarchical structure. It is characteristic of humans using human languages that we routinely construct sentences neither we nor anyone else has ever uttered. I'm betting that there are a bunch of these novel sentences in this blog.

Even more interesting are cases of what are often called "unbounded dependencies." Observe that in sentence 5, no less than in 4, "which girl" is the object of the verb "likes."

5. Which girl did Barry tell Sam that {John likes e}?

I am using "e" to draw attention to this fact. This ability is a very exciting one, especially when one realizes that the limitations of humans to handle such phenomena have more to do with our short term memory limitations than our cognitive abilities. I think that most people would have little trouble handling a sentence like 6. in which "which girl" is still the object of "likes."

6. Which girl {did Barry tell Sam that {Susan thinks {John likes e}}}.

It is because of data like 6 that the dependency between "which girl" and "e" (the extraction site) that we say that this phenomenon is unbounded.

The question is whether Bonobos or other apes can handle such phenomena. No one has ever proved they can to my knowledge. And until they can prove this I will be disinclined to think that they have "sophisticated language skills." One of the problems with evaluating claims made about the language skills of apes is that researchers have sometimes exaggerated their abilities. I would recommend that one examine any such claims with a skeptical eye.

Every study I have ever read which has tried to compare ape language skills with human language skills has put the former at about the 2 to 3 year old levels. This is a nontrivial accomplishment but falls short of showing that these primates have anything like the competence of human adults or even 12 year old children. One of the problems in teaching primates language is that the ideal form of language to teach is ASL since their ability to make human language sounds is severely limited and it has proved to be difficult to teach them to sign in part because it involves "modeling" the signs by physically helping the primate to make the sign. Remarkably, I just found an Ohio State University web page discussing the teaching of sign language to infants as young as 9 months. It seems that human infants have sufficient motor skills to do some signing before they have the motor skills required to produce human speech. This is wild and crazy stuff.

Researchers seem to have had more success teaching apes to use of plastic chips as symbols for things or keys on a keyboard. Though it is just a PowerPoint summary type presentation, you may find Apes using sign- or symbol-based languages useful as a summary of efforts to teach primates language. If you can't load that set of pages, you may find this html page helpful.

Let us recall though that absence of evidence that primates have a language ability comparable to humans is not evidence of its absence. There are real problems involved in teaching primates language having to do with their physical limitations both in regard to producing sounds and making the manual gestures required for something like ASL. And there is Wittgenstein's claim that even if a lion could talk we couldn't understand it to deal with it. There is an interesting thread at the Philosophy Forum on this. I side with Tsunami's remark, which was the second item in the thread. A chimpanzee or bonobo simply may not care about the sorts of things we like to talk about. It likes food and to play and to do other primate things. The concept of "liking someone," essential to understanding sentences 1 through 6 may be so foreign to the world of the Chimpanzee or Bonobo that it could simply not understand it.

I'm going to stop here and collect your thoughts before proceeding. Besides this blog is already overlong. Next we will focus on what can be learned by my fairly ignorant self about the evolution of human and other primate's sound production devices and brains. As you will discover, I use writing as a stimulus to learning.

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Tags: communication, language, sign language, ASL, bonobos, chimpanzees, human infants, origin of language