Inside of a Dog: What Dogs See, Smell, and Know (13 page)

Thunder outside. Pump's ears, velvet equilateral triangles that fold perfectly along the side of her head, prick into long isosceles. Head up, eyes to the window, she identifies the sound: a storm, a frightful thing. Her ears pivot back, flattened along her skull as if to hold them shut by their own force. I coo to her consolingly and watch her ears for feedback. The tips soften but she relaxes only slightly, still holding them tight against the roar.

By natural design, dogs' ears have evolved to hear certain kinds of sounds. Happily, that set of sounds overlaps with those we can hear and produce: if we utter it, it will at least hit the eardrum of a nearby dog. Our auditory range is from 20 hertz to 20 kilohertz: from the lowest pitch on the longest organ pipe to an impossibly squeaky squeak.* We spend most of our time straining to understand sounds between 100 hertz and 1 kilohertz, the range of any interesting speech going on in the vicinity. Dogs hear most of what we hear and then some. They can detect sounds up to 45 kilohertz, much higher than the hair cells of our ears bother to bend to. Hence the power of the dog whistle, a seemingly magical device that makes no apparent sound and yet perks the ears of dogs for blocks around. We call this sound "ultrasonic," since it's beyond our ken, but it is within the sonic range for many animals in our local environment. Don't think for a moment that apart from the occasional dog whistle, the world is quiet for dogs up at those high registers. Even a typical room is pulsing with high frequencies, detectable by dogs constantly. Think your bedroom is quiet when you rise in the morning? The crystal resonator used in digital alarm clocks emits a never-ending alarm of high-frequency pulses audible to canine ears. Dogs can hear the navigational chirping of rats behind your walls and the bodily vibrations of termites within your walls. That compact fluorescent light you installed to save energy? You may not hear the hum, but your dog probably can.

The range of pitches we are most intent on are those used in speech. Dogs hear all sounds of speech, and are nearly as good as we are at detecting a change of pitch—relevant, say, for understanding statements, which end in a low pitch, versus questions, which in English end in a raised pitch: "Do you want to go for a walk(?)" With the question mark, this sentence is exciting to a dog with experience going on walks with humans. Without it, it is simply noise. Imagine the confusion generated by the recent growth of "up-talking," speech that ends every sentence with the sound of a question?

If dogs understand the stress and tones—the
prosody
—of speech, does this hint that they understand language? This is a natural but vexed question. Since language use is one of the most glaring differences between the human animal and all other animals, it has been proposed as the ultimate, incomparable criterion for intelligence. This raises serious hackles in some animal researchers (not thought of as a hackled species, ironically), who have set about trying to demonstrate what linguistic ability animals have. Even those researchers who may agree that language is necessary for intelligence have nonetheless added reams of results to the growing pile of evidence of linguistic ability in non-human animals. All parties agree, though, that there has been no discovery of a humanlike language—a corpus of infinitely combinable words that often carry many definitions, with rules for combining words into meaningful sentences—in animals.

This is not to say that animals might not understand some of our language use, even if they don't produce it themselves. There are, for instance, many examples of animals taking advantage of the communicative system of nearby unrelated animal species. Monkeys can make use of nearby birds' warning calls of a nearby predator to themselves take protective action. Even an animal who deceives another animal by mimicry—which some snakes, moths, and even flies can do—is in some way using another species's language.

The research with dogs suggests that they do understand language—to a limited degree. On the one hand, to say that dogs understand
words
is a misnomer. Words exist in a language, which itself is product of a culture; dogs are participants in that culture on a very different level. Their framework for understanding the application of the word is entirely different. There is, no doubt, more to the words of their world than Gary Larson's
Far Side
comics suggest: eat, walk, and fetch. But he is on to something, insofar as these are organizing elements of their interaction with us: we circumscribe the dog's world to a small set of activities. Working dogs seem miraculously responsive and focused compared to city pets. It is not that they are innately more responsive or focused, but that their owners have added to their vocabularies types of things to do.

One component in understanding a word is the ability to discriminate it from other words. Given their sensitivity to the prosody of speech, dogs do not always excel at this. Try asking your dog on one morning to
go for a walk;
on the next, ask if your dog wants to
snow forty locks
in the same voice. If everything else remains the same, you'll probably get the same, affirmative reaction. The very first sounds of an utterance seem to be important to dog perception, though, so changing the swallowed consonants for articulated ones and the long vowels for short ones—
ma
for
a
polk?
—might prompt the confusion merited by this gibberish. Of course humans read meaning into prosody, too. English does not give the prosody of speech syntactical leverage but it is still part of how we interpret "what has just been said."

If we were more sensitive to the
sound
of what we say to dogs, we might get better responses from them. High-pitched sounds mean something different than low sounds; rising sounds contrast with falling sounds. It is not accidental that we find ourselves cooing to an infant in silly, giddy tones (called
motherese
)—and might greet a wagging dog with similar baby talk. Infants can hear other speech sounds, but they are more interested in motherese. Dogs, too, respond with alacrity to baby talk—partially because it distinguishes speech that is directed
at
them from the rest of the continuous yammering above their heads. Moreover, they will come more easily to high-pitched and repeated call requests than to those at a lower pitch. What is the ecology behind this? High-pitched sounds are naturally interesting to dogs: they might indicate the excitement of a tussle or the shrieking of nearby injured prey. If a dog fails to respond to your reasonable suggestion that he come
right now,
resist the urge to lower and sharpen your tone. It indicates your frame of mind—and the punishment that might ensue for his prior uncooperativeness. Correspondingly, it is easier to get a dog to
sit
on command to a longer, descending tone rather than repeated, rising notes. Such a tone might be more likely to induce relaxation, or preparation for the next command from their talky human.

There is one celebrated dog whose word usage is exceptional. Rico, a border collie in Germany, can identify over two hundred toys by name. Given an enormous heap of all the toys and balls he has ever seen, he can reliably pull out and retrieve the one his owner requests. Now, putting aside why a dog might need two hundred toys, this ability is impressive. Children are hard-pressed to do the same task (and are only sometimes helpful in bringing things back). Even better, Rico can quickly learn a name for a new object, by process of elimination. Experimenters put a novel toy among familiar ones and asked him, using a word he had never heard before, to retrieve it.
Go get the snark, Rico.
One would be sympathetic if he looked bemused, and wandered back with a favorite toy in his chops. Instead, though, Rico reliably picked out the new toy:
naming
it.

Rico was not using language, of course, in the way we, or even young children, do. One can debate how much he was
understanding,
or if he was even doing anything other than showing a preference for the new object. On the other hand, he was showing an astute ability to satisfy the humans making various sounds by picking up the referents of those sounds. His ability might not indicate that all dogs are so able: Rico might be an unusually skilled word user*

—and he is definitely unusually motivated by the praise received on retrieving the right toy. Still, even if he were the only dog who does this, it indicates that the dog's cognitive equipment is good enough to understand language in the right context.

It is not only the express content or sound of speech that carries meaning. Being a competent language user means understanding the pragmatics of usage: how the means, form, and context of what you say also affect the meaning of what you say. Paul Grice, a twentieth-century philosopher, famously described various "conversational maxims," known to us implicitly, that regulate language use. Their use marks you as a cooperative speaker; even their express violation is often meaningful. They include the charming maxim of relation (be relevant), the maxim of manner (be brief and clear), and maxims of quality (tell the truth) and quantity (say only as much as you need to).

On a good day, dogs mind all of Grice's maxims. Consider a dog who espies a roguish-looking fellow down the street. The dog may bark (relevant: the guy is roguish-looking) sharply (quite unambiguous), but only as long as the fellow is around (so the warning bark is currently true), and not more than a few times (relatively pithy). While dogs hardly qualify as competent language users, it is notably not because of their violation of the pragmatics of communication. It is only the smallness of their vocabulary and restricted use of words in combination that disqualifies them.

Many owners lament that, by contrast to Rico, their dogs are not terrific listeners—despite their broad range of audition. To be fair, canids do not rely on hearing as their primary sense. Relative to even our hearing, their ability to pinpoint where a sound is coming from is imprecise. They hear sounds unmoored from their origins. And just like us, they must bring attention to a noise to hear it best—first apparent in the familiar tilt of the head, to direct the ears slightly toward the sound source, or in radar-dish adjustments of the pinnae. Instead of being used to "see" the source of the sound, their auditory sense seems to serve an ancillary function: helping dogs find the general direction of a sound, at which point they can turn on a more acute sense, like olfaction or even vision, to investigate further.

Dogs themselves make a variety of sounds across a range of pitches or differing only by subtle alterations in tempo or frequency. They are downright noisy.

Her slow, light panting, mouth open partway, tongue purple and wet and perfect. Pump's panting was a conversation in and of itself—I always felt talked-to when she panted at me.

The cacophony of a packed dog run seems at first pass to be an undifferentiated racket. With closer attention, though, one can distinguish shouts from cries; yelps from barks; and play barks from threatening barks. Dogs make sounds both intentionally and inadvertently. Both kinds may hold information, the minimum requirement to call an aural disturbance a "communication" rather than simply "noise." What is interesting for scientists is determining the meaning of that information. Given the way dogs wield these noises, there is no doubt that they have different meanings.

Countless hours of researchers' lives spent listening to animals shout, coo, click, groan, and scream has led to the discovery of some universal features of sound signals. They either express something about the world—a discovery, a danger—or something about the signalers themselves—their identity, sexual status, rank, membership in a group, fear, or pleasure. They effect a change in others: they may decrease social distance between the signaler and those around him, calling someone closer; or increase social distance, frightening someone away. In addition, sounds may serve to cohere a group (in defense from a predator or intruder, for instance) or they may elicit maternal or sexual affiliation. Ultimately, all these purposes for making sounds make evolutionary sense: they aid the animal in securing its survival or the survival of its relatives.