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The last word: Inside a dog’s world
Author Alexandra Horowitz explains why dogs pee on hydrants, lick our faces, and are always sniffing.
The Last Word
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Friday, September 25, 2009
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The last word: Inside a dog’s world

A dog's nose is millions of times more sensitive than a human's.

(Radius Images/Corbis)

GO LOOK AT a dog. Go on, look—maybe at one lying near you right now, curled around his folded legs on a dog bed, or sprawled on his side on the tile floor, paws flitting through the pasture of a dream. Take a good look—and now forget everything you know about dogs. Because forgetting what we think we know is the best way to begin understanding dogs.

The first things to forget are anthropomorphisms. We see, talk about, and imagine dogs’ behavior from a human-biased perspective. Of course, we’ll say, dogs love and desire; of course they dream and think; they also know and understand us, feel bored, get jealous, and get depressed. What could be a more natural explanation of a dog staring dolefully at you as you leave the house for the day than that he is depressed that you’re going?

The answer is an explanation based in what dogs actually have the capacity to feel, know, and understand.

If we want to understand the life of any animal, we need to know what things are meaningful to it, beginning with what it can perceive—what it can see, hear, smell, or otherwise sense. Second, we need to consider how the animal acts on the world.

WE HUMANS TEND not to spend a lot of time thinking about smelling, for instance. Smells are minor blips in our sensory day compared to the reams of visual information that we take in. The room I’m in right now is a phantasmagoric mix of colors and surfaces and densities, of shadows and lights. Oh, and if I really call my attention to it, I can smell the coffee on the table next to me. But as humans see the world, a dog smells it. The dogs’ universe is a stratum of complex odors.

Consider too that dogs don’t act on the world by handling objects or by eyeballing them. Instead, they bravely stride right up to a new unknown object, stretch their magnificent snouts within millimeters of it, and take a nice deep sniff. That dog nose, in most breeds, is anything but subtle. The snout holding the nose projects forth to examine a new person seconds before the dog himself arrives on the scene. And the sniffer is not just an ornament atop the muzzle; it is the leading, moist headliner. What its prominence suggests, and what all science confirms, is that the dog is a creature of the nose.

The sniff is the great medium for getting smelly objects to the dog, the tramway on which chemical odors speed up to the waiting receptor cells lining the caverns of the dog’s nose. Human noses have about 6 million of these receptor sites; beagle noses have more than 300 million. The difference in the smell experience is exponential. Next to a beagle, we are downright anosmic, smelling nothing. We might notice if our coffee’s been sweetened with a teaspoon of sugar; a dog can detect a teaspoon of sugar diluted in a million gallons of water.

What’s this like? Imagine if each detail of our visual world were matched by a corresponding smell. Each petal on a rose may be distinct, having been visited by insects leaving pollen footprints from faraway flowers. What is to us just a single stem actually holds a record of who held it, and when. A burst of chemicals marks where a leaf was torn. Imagine smelling every minute visual detail. That might be the experience of a rose to a dog.

And dogs put their remarkable sense of smell to great use socially. While we humans leave our scents behind inadvertently, dogs are profligate with their scents. It is as though dogs, realizing how much can be learned from odor, are determined to use this to their advantage. Dogs—like all other canids—leave urine conspicuously splashed on all manner of object. Urine marking, as this method of communication is called, conveys a message. Every dog owner is familiar with the raised-leg marking of fire hydrants, lampposts, trees, bushes. Most marked spots are high or prominent: better to be seen, and better for the odor to be smelled.

From observations of the behavior of sniffing dogs, it appears that the chemicals in the urine give information about, for females, sexual readiness, and for males, their social confidence. The prevailing myth is that the message is “this is mine,” that dogs urinate to “mark territory.” But research has failed to bear this out as the exclusive, or even predominant, use of urine marking. Instead, marking seems to leave information about who the urinator is, how often he walks by this spot, his recent victories, and his interest in mating. In this way, the invisible pile of scents on the hydrant becomes a community bulletin board, with old, deteriorating announcements and requests peeking out from underneath more recent posts.

SPENDING AN AFTERNOON at home at the height of a dog can generate many surprises. But the objects you would see when crawling around on all fours are not, in some sense, the same objects a dog sees. A dog looking around a room does not think he is surrounded by human things; he sees—and smells—dog things.

What we may think an object is for, or what it makes us think of, may or may not match the dog’s idea of the object’s function or meaning. Objects are defined by how you can act upon them: what the German biologist Jakob von Uexküll called their “functional tone.” A dog may be indifferent to chairs, but if trained to jump on one, he learns that the chair has a sitting tone: It can be sat upon. But other things that we may identify as chair-like are not so seen by dogs: stools, tables, arms of couches. Stools and tables are in some other category of objects: obstacles, perhaps, in their path toward the eating tone of the kitchen. A ball, a pen, a teddy bear, and a shoe are in some ways equivalent: All are objects that one can get one’s mouth around.

Here we begin to see how the dog and human overlap in their worldviews, and how we differ. A good many objects in the world have an eating tone to the dog—probably many more than we see as such. Feces just aren’t menu items for us; dogs disagree. Dogs may have tones that we don’t have at all—rolling tones, say: things that one might merrily roll in. And plenty of objects that have very specific meanings to us—forks, knives, hammers, pushpins, fans, clocks—have little or no meaning to dogs. To a dog, a hammer doesn’t exist. A dog doesn’t act with or on a hammer, so it has no significance to a dog. At least, not until it overlaps with some other, meaningful object: It is wielded by a loved person; it is urinated on by the cute dog down the street.

I FREQUENTLY HEAR dog owners verify their dogs’ love of them through the kisses delivered upon them when they return home. These “kisses” are licks: slobbery licks to the face; focused, exhaustive licking of the hand; solemn tongue-polishing of a limb. I confess that I treat the licks that my dog Pump bestows on me as signs of affection. “Affection” and “love” are not just the recent constructs of a society that treats pets as little people, to be shod in shoes in bad weather, dressed up for Halloween, and indulged with spa days. Before there was any such thing as doggy day care, Charles Darwin himself wrote of receiving lick-kisses from his dogs. He was certain of their meaning: Dogs have, he wrote, a “striking way of exhibiting their affection, namely, by licking the hands or faces of their masters.” Was Darwin right? The kisses feel affectionate to me, but are they gestures of affection to the dog?

First, the bad news: Researchers of wild canids—wolves, coyotes, foxes, and other wild dogs—report that puppies lick the face and muzzle of their mother when she returns from a hunt to her den, in order to get her to regurgitate for them. Licking around the mouth seems to be the cue that stimulates her to vomit up some nicely partially digested meat. How disappointed Pump must be that not a single time have I regurgitated half-eaten rabbit flesh for her.

Furthermore, our mouths taste great to dogs. Like wolves and humans, dogs have taste receptors for salty, sweet, bitter, sour, and even umami, the earthy, mushroomy-seaweedy flavor captured in the flavor-heightening monosodium glutamate. Eventually I realized that Pump’s licks to my face often correlated with my face having just overseen the ingestion of a good amount of food.

Now the good news: As a result of this functional use of mouth licking—“kisses” to you and me—the behavior has become a ritualized greeting. In other words, it no longer serves only the function of asking for food; now it is used to say hello. Dogs and wolves muzzle-lick simply to welcome another dog back home, and to get an olfactory report of where the homecomer has been or what he has done. Familiar dogs may exchange licks when meeting at their ends of their respective leashes on the street. It may serve as a way to confirm, through smell, that this dog storming toward them is who they think he is. Since these “greeting licks” are often accompanied by wagging tails, mouths opened playfully, and general excitement, it is not a stretch to say that the licks are a way to express happiness that you have returned.

WHAT ABOUT A dog’s power of visual and mental perception? Look a dog in the eyes and you get the definite feeling that he is looking back. Dogs return our gaze. They are looking at us in the same way that we look at them. Naturally we wonder, is the dog thinking about us the way we are thinking about the dog?

In fact, we are known by our dogs probably far better than we know them. They are the consummate eavesdroppers and Peeping Toms: Let into the privacy of our rooms, they quietly spy on our every move. They know about our comings and goings. They know whom we sleep with, what we eat. We share our homes with uncounted numbers of mice, millipedes, and mites—none bothers to look our way. Dogs, by contrast, watch us from across the room, from the window, and out of the corners of their eyes. Their sight is used to see what we attend to. In some ways, this is similar to us, but in other ways it surpasses human capacity.

Dogs are anthropologists among us. They are students of our behavior. And what makes them especially good anthropologists is that they never tire of attending to minute changes in our expressions, our moods, our outlooks. Unlike us, they don’t become inured to people.