(Page references below are to the optional reading selection from Dr Dolittle’s Delusion.)
We were saying that animals have sometimes been documented passing on skills or knowledge they learn to their communities and offspring. Examples include elephants teaching their young about migration routes and where water holes can be found, and snow monkeys who figured out how to wash sweet potatos before eating them.
But not all teaching or communication involves signals (sounds, gestures) in ways that invite counting them as a language. Here are some other criteria that researchers consider.
Do animals ever correlate arbitrary signals with what they mean? Or only signals that are instinctually hard-wired, or that sound like what they’re referring to (like imitating the sound of a fire truck)? Sometimes these correlations are arbitrary.
One question is whether some signals only express an animal’s internal state, or whether they communicate something about the outside world. If the latter, can they be about things that aren’t (or don’t seem to be) immediately present (“displacement”)?
For at least some animals — vervet monkeys in the wild, some apes in lab settings, Alex the gray parrot (the real-life model for “Chiapa” in the Star Witness reading) — there’s good evidence that signals can be about outside objects, and can in some cases request items that aren’t yet present.
The author of Dr Dolittle’s Delusion discusses when is it reasonable to interpret alarm calls as referring to (“denoting,” “meaning”) things in the outside world — such as particular kinds/categories of danger — as opposed to just expressing “I’m scared” or some other aspect of the animal’s internal state, such as “I’m going to run”?
For ground squirrels, our evidence best supports that alarm calls just reflect the animal’s internal feeling of urgency or fright (pp. 170-1). With vervet monkeys, on the other hand, our evidence supports that their alarm calls also communicate information about the kind/category of external danger. Arguments for this are summarized starting on p. 171.
Against the hypothesis that an alarm call means the action a vervet is about to take, the author counters: [W]hat the vervet actually does after giving the call varies. The monkey may do nothing at all, or may climb up a tree, or may climb down from a tree, without any necessary and inflexible relation between call and action.
(p. 189)
Against the hypothesis that it means I’m scared or something like that, the author points out that vervets don’t give the calls when alone, and are more likely to give them in the presence of their close family than other members of their group. The author concludes: [A]ll of these features demonstrate that alarm calling is sensitive (at least) to the audience, which means it cannot simply be a direct reflection of the monkey’s internal state of alarm. Rather than being merely expressive, vervets perhaps produce alarm calls in order to influence the behavior of the other vervets, to get them to take appropriate evasive action with respect to the specific threat that is at hand.
(p. 189)
Those arguments tell us that the monkeys’ alarm calls don’t just mean “I’m scared” or “I’m going to run.” Instead they seem to mean something about the outside world. But it’s still an open question what they say about the outside world. Does a given alarm call mean “Leopard”? Or perhaps “Predator that attacks from the ground”? Or perhaps “Danger: go climb a tree!” On pp. 190-1, the author discusses some considerations that might better support this last interpretation.
Sometimes animals combine multiple signals into wholes with new meanings. Do these combinations ever have a “syntactic structure” in the way human languages do, or are they only an “unstructured linguistic soup”?
No one would expect animals to have the same syntax as any human language; but do their communications at least exhibit some of the fundamental structural properties of our languages? These include:
Words combining into phrases that group together:
Mary is across the street. Mary’s dog is across the street. Mary’s small dog is across the street. Mary’s small dog that is afraid of Paula is across the street.
There being structure to phrases that goes beyond their superficial order. Consider:
Pat ridiculed [Harry’s theory that Mary was across the street]. Pat persuaded [Harry’s students] [that Mary was across the street.]
The difference between these shows up when you convert them into passive forms. For the first sentence, it would be grammatical to say “Harry’s theory that Mary was across the street was ridiculed by Pat.” It would sound awful to say “Harry’s theory was ridiculed by Pat that Mary was across the street.” (You could get away with “Harry’s theory was ridiculed by Pat — I mean his theory that Mary was across the street.”) With the second sentence, though, the situation is reversed. Saying “Harry’s students that Mary was across the street were persuaded by Pat” sounds awful. “Harry’s students were persuaded by Pat that Mary was across the street” sounds fine.
This is taken to be compelling evidence that our original two sentences have different underlying structures (indicated by the square brackets [ ]).
Phrases can interact with elements they aren’t immediately adjacent to, in the “surface order” of the sentence. Consider:
Mary is too embarrassing to ask anyone to dance with. Mary is too embarrassed to ask anyone to dance with Bill.
Notice how in the first sentence, nothing comes at the end after “with.” It’s understood that we’re talking about dancing with Mary. You could be more explicit and say “too embarrassing to ask anyone to dance with her,” but it’s also OK to leave it implicit that you mean Mary. With the second sentence, on the other hand, you have to explicitly say who you’re talking about dancing with. In the example, we say “dance with Bill,” but it’d also be OK to say “dance with her,” meaning Mary. It would not be OK to leave it implict, by saying “Mary is too embarrassed to ask anyone to dance with” and then stopping with a period. Notice also it’s understood that in the first sentence, we’re talking about the prospect of us the speakers asking something. Whereas in the second sentence, we’re talking about the prospect of Mary asking something. All of these differences in the sentences come from the choice of saying “too embarrassing” versus “too embarrassed.” The effect that choice has on who’s understood to be doing the asking is a “local” one: it affects how the next words in the sentence’s surface order are understood. But the effect it has on whether the object of “with” can be left implicit is more distant.
In Chapter 10 the author of Dr Dolittle’s Delusion argues there is no compelling evidence for attributing any of these kinds of structure to animal communications.