Inside Of A Dog Part 3

Even without knowing the specific differences in the Labrador retriever's and the Australian shepherd's reaction to that rabbit, there is one thing that may account for the variability in behavior between breeds. They have different threshold levels threshold levels to notice and react to stimuli. The same rabbit, for instance, causes different amounts of excitement in two different dogs; similarly, the same amount of hormone producing that excitement causes different rates of response, from raising a head in mild interest, to a full-on chase. to notice and react to stimuli. The same rabbit, for instance, causes different amounts of excitement in two different dogs; similarly, the same amount of hormone producing that excitement causes different rates of response, from raising a head in mild interest, to a full-on chase.

There is a genetic explanation behind this. Though we call a dog a retriever or a shepherd, it is not the behavior retrieving retrieving or or shepherding shepherding that was selected for. Instead, it was the likelihood that the dog would respond just the right amount to various events and scenes. However, there is no one gene we can point to here. No gene develops right into that was selected for. Instead, it was the likelihood that the dog would respond just the right amount to various events and scenes. However, there is no one gene we can point to here. No gene develops right into retrieving retrieving behavior-or into any particular behavior at all. But a set of genes may affect the likelihood that an animal acts in a certain way. In humans, too, a genetic difference between individuals may appear as different propensities to certain behaviors. One might be more or less susceptible to becoming addicted to stimulant drugs, based partly on how much stimulation one's brain needs to produce a pleasurable feeling. Addictive behavior is thereby traceable to genes that design the brain-but there is no gene for behavior-or into any particular behavior at all. But a set of genes may affect the likelihood that an animal acts in a certain way. In humans, too, a genetic difference between individuals may appear as different propensities to certain behaviors. One might be more or less susceptible to becoming addicted to stimulant drugs, based partly on how much stimulation one's brain needs to produce a pleasurable feeling. Addictive behavior is thereby traceable to genes that design the brain-but there is no gene for addiction. addiction. The environment is clearly important here, too. Some genes regulate expression of other genes-which expression might depend on features of the environment. If raised in a box, without access to drugs, one never develops a drug problem, regardless of one's propensity to addiction. The environment is clearly important here, too. Some genes regulate expression of other genes-which expression might depend on features of the environment. If raised in a box, without access to drugs, one never develops a drug problem, regardless of one's propensity to addiction.

In the same way, one breed of dog can be distinguished from others by its propensity to respond to certain events. While all dogs can see birds taking flight in front of them, some are particularly sensitive to the small quick motion of something going aloft. Their threshold to respond to this motion is much lower than for dogs not bred to be hunting companions. By comparison to dogs, our response threshold is higher still. We humans can certainly see the birds taking off, but even when they are directly in front of us, we might not notice them. In hunting dogs, the motion is not only noticed, it is directly connected to another tendency: to pursue prey that moves in just that way. And, of course, one must have birds or birdlike things around for this tendency to lead to bird chasing.

Similarly, a sheepdog who will spend his life herding sheep is one who has a certain set of specific tendencies: to notice and keep track of individuals of a group, to detect the errant motion of a sheep moving away from the herd, and to have a drive to keep the herd together. The end result is a herding dog, but his behavior is made up of piecemeal tendencies that shepherds direct toward controlling their sheep. The dog must also be exposed to sheep early in his life, or these propensities wind up being applied not to sheep, but in a disorganized way to young children, to people jogging in the park, or to the squirrels in your yard.

A dog breed that is called aggressive, aggressive, then, is one that might have a lower threshold to perceive and react to a threatening motion. If the threshold is too low, then even neutral motion-approaching the dog-may be perceived as threatening. But if the dog is not encouraged to follow through on this tendency, it is quite likely that he will never exhibit the aggression that his breed is notorious for. then, is one that might have a lower threshold to perceive and react to a threatening motion. If the threshold is too low, then even neutral motion-approaching the dog-may be perceived as threatening. But if the dog is not encouraged to follow through on this tendency, it is quite likely that he will never exhibit the aggression that his breed is notorious for.

Knowing the breed of a dog gives us a first-pa.s.s entry into understanding something about the dog before we have even met the dog. But it is a mistake to think that knowing a breed guarantees that it will behave as advertised-only that it has certain tendencies. What you get with a mixed-breed dog is a softening of the hard edges seen in breeds. Temperaments are more complex: averaged versions of their bred forebears. In any event, naming a dog's breed is only the beginning of a true understanding of the dog's umwelt, not an endpoint: it doesn't get to what the dog's life is about to the dog. to the dog.

ANIMALS WITH AN ASTERISK.

It's snowing and dawn is breaking, which means we have about three minutes for me to get dressed and get us into the park to play before the snow is trammeled by other merrymakers. Outside, well bundled, I plow clumsily through the deep snow, and Pump hurtles herself through it with great bounds, leaving the footprints of a giant bunny. I plop down to make a snow angel, and Pump throws herself down beside me and seems to be making a snow-dog angel, twisting to and fro on her back. I look to her with complete joy at our shared play. Then I smell a horrible odor coming from her direction. The realization is quick: Pump's not making a snow-dog angel; she's rolling in the decaying carca.s.s of a small animal.

There is a tension between those who consider dogs wild animals at their core and those who consider dogs creatures of our own making. The first group tends to turn to wolf behavior to explain dog behavior. The recently popular dog trainers are admired for their full embrace of the wolf side of dogs. They are often seen mocking the second group, which treats their dogs as quadrupedal, s...o...b..ry people. Neither has got it right. The answer is plumb in the middle of these approaches. Dogs are animals, of course, with atavistic tendencies, but to stop here is to have a blinkered view of the natural history of the dog. They have been retooled. Now they are animals with an asterisk.

The inclination to look at dogs as animals rather than creations of our psychology is essentially right. To avoid anthropomorphizing, some turn to what might be called unsympathetic biology: a biology free of subjectivity or such messy considerations as consciousness, preferences, sentiment, or personal experiences. A dog is but an animal, they say, and animals are but biological systems whose behavior and physiology can be explained with simpler, general-purpose terminology. Recently I saw a woman leaving the pet store with her terrier, who himself was newly shod in four tiny shoes-to prevent his bringing the street filth into her house, she explained, as she pulled him skating on rigid limbs down the filthy street. This woman could benefit from more reflection on her dog's animal nature, and less on his resemblance to a stuffed toy. In fact, as we'll see, understanding some of the dogs' complexities-the acuity of their noses, what they can see and cannot see, their loss of fearfulness, and the simple affect of a wag-goes a long way to understanding dogs.

On the other hand, in a number of ways, calling a dog just an animal, just an animal, and explaining all dog behavior as emerging from wolf behavior, is incomplete and misleading. The key to dogs' success living with us in our homes is the very fact that dogs are not wolves. and explaining all dog behavior as emerging from wolf behavior, is incomplete and misleading. The key to dogs' success living with us in our homes is the very fact that dogs are not wolves.

For instance, it is high time we revamp the false notion that our dogs view us as their "pack." The "pack" language-with its talk of the "alpha" dog, dominance, and submission-is one of the most pervasive metaphors for the family of humans and dogs. It originates where dogs originated: dogs emerged from wolflike ancestors, and wolves form packs. Thus, it is claimed, dogs form packs. The seeming naturalness of this move is belied by some of the attributes we don't don't transfer from wolves to dogs: wolves are hunters, but we don't let our dogs hunt for their own food.* And though we may feel secure with a dog at the threshold of a nursery, we would never let a wolf alone in a room with our sleeping newborn baby, seven pounds of vulnerable meat. transfer from wolves to dogs: wolves are hunters, but we don't let our dogs hunt for their own food.* And though we may feel secure with a dog at the threshold of a nursery, we would never let a wolf alone in a room with our sleeping newborn baby, seven pounds of vulnerable meat.

Still, to many, the a.n.a.logy to a dominance-pack organization is terribly appealing-especially with us as dominant and the dog submissive. Once applied, the popular conception of a pack works itself into all sorts of interactions with our dogs: we eat first, the dog second; we command, the dog obeys; we walk the dog, the dog doesn't walk us. Unsure how to deal with an animal in our midst, the "pack" notion gives us a structure.

Unfortunately, it not only limits the kind of understanding and interaction we can have with our dogs, it also relies on a faulty premise. The "pack" evoked in this way bears little resemblance to actual wolf packs. The traditional model of the pack was that of a linear hierarchy, with a ruling alpha pair and various "beta" and even "gamma" or "omega" wolves below them, but contemporary wolf biologists find this model far too simplistic. It was formed from observations of captive captive wolves. With limited s.p.a.ce and resources in small, enclosed pens, unrelated wolves self-organize, and a hierarchy of power results. The same might happen in any social species confined with little room. wolves. With limited s.p.a.ce and resources in small, enclosed pens, unrelated wolves self-organize, and a hierarchy of power results. The same might happen in any social species confined with little room.

In the wild, wolf packs consist almost entirely of related or mated animals. They are families, families, not groups of peers vying for the top spot. A typical pack includes a breeding pair and one or many generations of their offspring. The pack unit organizes social behavior and hunting behavior. Only one pair mates, while other adult or adolescent pack members partic.i.p.ate in raising the pups. Different individuals hunt and share food; at times, many members together hunt large prey which may be too large to tackle individually. Unrelated animals do occasionally join together to form packs with multiple breeding partners, but this is an exception, probably an accommodation to environmental pressures. Some wolves never join a pack. not groups of peers vying for the top spot. A typical pack includes a breeding pair and one or many generations of their offspring. The pack unit organizes social behavior and hunting behavior. Only one pair mates, while other adult or adolescent pack members partic.i.p.ate in raising the pups. Different individuals hunt and share food; at times, many members together hunt large prey which may be too large to tackle individually. Unrelated animals do occasionally join together to form packs with multiple breeding partners, but this is an exception, probably an accommodation to environmental pressures. Some wolves never join a pack.

The one breeding pair-parents to all or most of the other pack members-guides the group's course and behaviors, but to call them "alphas" implies a vying for the top that is not quite accurate. They are not alpha dominants any more than a human parent is the alpha in the family. Similarly, the subordinate status of a young wolf has more to do with his age than with a strictly enforced hierarchy. Behaviors seen as "dominant" or "submissive" are used not in a scramble for power, they are used to maintain social unity. Rather than being a pecking order, rank is a mark of age. It is regularly on display in the animals' expressive postures in greeting and in interaction. Approaching an older wolf with a low wagging tail and a body close to the ground, a younger wolf is acknowledging the older's biological priority. Young pups are naturally at a subordinate level; in mixed-family packs pups may inherit some of the status of their parents. While rank may be reinforced by charged and sometimes dangerous encounters between pack members, this is rarer than aggression against an intruder. Pups learn their place by interacting with and observing their packmates more than by being put in their place.

The reality of wolf pack behavior contrasts starkly with dog behavior in other ways. Domestic dogs do not generally hunt. Most are not born into the family unit in which they will live: with humans the predominant members. Pet dogs' attempts to mate are (happily) unrelated to their adopted humans'-supposedly the alpha pair's-mating schedules. Even feral dogs-those who may never have lived in a human family-usually do not form traditional social packs, although they may travel in parallel.

Neither are we the dog's pack. Our lives are so much more stable than that of a wolf pack: the size and members.h.i.+p of a wolf pack is always in flux, changing with the seasons, with the rates of offspring, with young adult wolves growing up and leaving in their first years, with the availability of prey. Typically, dogs adopted by humans live out their lives with us; no one is pushed out of the house in spring or joins us just for the big winter moose hunt. What domestic dogs do seem to have inherited from wolves is the sociality of a pack: an interest in being around others. Indeed, dogs are social opportunists. They are attuned to the actions of others, and humans turned out to be very good animals to attune to.

To evoke the outdated, simplistic model of packs glosses over real differences between dog and wolf behavior and misses some of the most interesting features of packs in wolves. We do better to explain dogs' taking commands from us, deferring to us, and indulging us by the fact that we are their source of food than by reasoning that we are alpha. We can certainly make dogs totally submissive to us, but that is neither biologically necessary nor particularly enriching for either of us. The pack a.n.a.logy does nothing but replace our anthropomorphisms with a kind of "beastomorphism," whose crazy philosophy seems to be something like "dogs aren't humans, so we must see them as precisely unhuman in every way."

We and our dogs come closer to being a benign gang than a pack: a gang of two (or three or four or more). We are a family. We share habits, preferences, homes; we sleep together and rise together; we walk the same routes and stop to greet the same dogs. If we are a gang, we are a merrily navel-gazing gang, wors.h.i.+ping nothing but the maintenance of our gang itself. Our gang works by sharing fundamental premises of behavior. For instance, we agree to rules of conduct in our home. I agree with my family that under no circ.u.mstances is urination on the living room rug allowed. This is a tacit agreement, happily. A dog has to be taught this premise for habitation; no dog knows about the value of rugs. In fact, rugs might provide a nice feeling underfoot for some bladder release.

Trainers who espouse the pack metaphor extract the "hierarchy" component and ignore the social context from which it emerges. (They further ignore that we still have a lot to learn about wolf behavior in the wild, given the difficulty of following these animals closely.) A wolfcentric trainer may call the humans the pack leaders responsible for discipline and forcing submission by others. These trainers teach by punis.h.i.+ng the dog after discovery of, say, the inevitable peed-upon rug. The punishment can be a yell, forcing the dog down, a sharp word or jerk of the collar. Bringing the dog to the scene of the crime to enact the punishment is common-and is an especially misguided tactic.

This approach is farther from what we know of the reality of wolf packs and closer to the timeworn fiction of the animal kingdom with humans at the pinnacle, exerting dominion over the rest. Wolves seem to learn from each other not by punis.h.i.+ng each other but by observing each other. Dogs, too, are keen observers-of our reactions. Instead of a punishment happening to to them, they'll learn best if you let them discover for themselves which behaviors are rewarded and which lead to naught. Your relations.h.i.+p with your dog is defined by what happens in those undesired moments-as when you return home to a puddle of urine on the floor. Punis.h.i.+ng the dog for his misbehavior-the deed having been done maybe hours before-with dominance tactics is a quick way to make your relations.h.i.+p about bullying. If your trainer punishes the dog, the problem behavior may temporarily abate, but the only relations.h.i.+p created is one between your trainer and your dog. (Unless the trainer's moving in with you, that won't last long.) The result will be a dog who becomes extra sensitive and possibly fearful, but not one who understands what you mean to impart. Instead, let the dog use his observation skills. Undesired behavior gets no attention, no food: nothing that the dog wants from you. Good behavior gets it all. That's an integral part of how a young child learns how to be a person. And that's how the dog-human gang coheres into a family. them, they'll learn best if you let them discover for themselves which behaviors are rewarded and which lead to naught. Your relations.h.i.+p with your dog is defined by what happens in those undesired moments-as when you return home to a puddle of urine on the floor. Punis.h.i.+ng the dog for his misbehavior-the deed having been done maybe hours before-with dominance tactics is a quick way to make your relations.h.i.+p about bullying. If your trainer punishes the dog, the problem behavior may temporarily abate, but the only relations.h.i.+p created is one between your trainer and your dog. (Unless the trainer's moving in with you, that won't last long.) The result will be a dog who becomes extra sensitive and possibly fearful, but not one who understands what you mean to impart. Instead, let the dog use his observation skills. Undesired behavior gets no attention, no food: nothing that the dog wants from you. Good behavior gets it all. That's an integral part of how a young child learns how to be a person. And that's how the dog-human gang coheres into a family.

CANIS UNFAMILIARIS.

On the other hand, let's not forget that it is only tens of thousands of years of evolution that separate wolves and dogs. We would have to go back millions of years to trace our split from chimpanzees; appropriately, we do not look to chimpanzee behavior to learn how to raise our children.* Wolves and dogs share all but a third of 1 percent of their DNA. We see occasional s.n.a.t.c.hes of wolf in our pets: a glimpse of a growl when you move to extract a beloved ball from your dog's mouth; rough-and-tumble play in which one animal seems more prey than playmate; a glimmer of wildness in the eye of a dog grabbing for a meat bone.

The orderliness of most of our interactions with dogs clashes mightily with their atavistic side. Once in a while it feels as if some renegade ancient gene takes a hold of the domesticated product of its peers. A dog bites his owner, kills the family cat, attacks a neighbor. This unpredictable, wild side of dogs should be acknowledged. The species has been bred for millennia, but it evolved for millions of years before that without us. They were predators. Their jaws are strong, their teeth designed for tearing flesh. They are wired to act before contemplating action. They have an urge to protect-themselves, their families, their turf-and we cannot always predict when they will be prompted to be protective. And they do not automatically heed the shared premises of humans living in civilized society.

As a result, the first time your dog tears from your side, running maniacally off the trail after some invisible thing in the bushes, you panic. With time, you will become familiar with each other: they, with what you expect of them; you, with what they do. It is only off the trail off the trail to you; to the dog it is a natural continuation of walking, and he will learn about trails in time. You may never see the invisible thing in the bush, but you learn, after a dozen walks, that invisible things are in bushes, and the dog will return to you. Living with a dog is a long process of becoming mutually familiar. Even the dog bite is not a uniform ent.i.ty. There are bites done out of fear, out of frustration, out of pain, and out of anxiety. An aggressive snap is different than an exploratory mouthing; a play bite is different than a grooming nibble. to you; to the dog it is a natural continuation of walking, and he will learn about trails in time. You may never see the invisible thing in the bush, but you learn, after a dozen walks, that invisible things are in bushes, and the dog will return to you. Living with a dog is a long process of becoming mutually familiar. Even the dog bite is not a uniform ent.i.ty. There are bites done out of fear, out of frustration, out of pain, and out of anxiety. An aggressive snap is different than an exploratory mouthing; a play bite is different than a grooming nibble.

Despite their sometime wildness, dogs never revert to wolves. Stray dogs-those who lived with humans but have wandered away or been abandoned-and free-ranging dogs-provisioned with food but living apart from humans-do not take on more wolflike qualities. Strays seem to live a life familiar to city dwellers: parallel to and cooperative with others, but often solitary. They do not self-organize socially into packs with a single breeding pair. They don't build dens for the pups or provide food for them as wolves do. Free-ranging dogs may form a social ordering like other wild canids-but one organized by age more than by fights and strife. Neither hunts cooperatively: they scavenge or hunt small prey by themselves. Domestication changed them.

Even when wolves have been socialized-raised from birth among humans instead of other wolves-they do not turn into dogs. They strike a middle ground in behavior. Socialized wolves are more interested in and attentive to humans than wild-born wolves. They follow human communicative gestures better than wild wolves. But they are not dogs in wolves' clothing. Dogs raised with a human caretaker prefer her company over that of other humans; wolves are less discriminating. Dogs far outpace hand-raised wolves in interpreting human cues. To see a wolf on a leash, sitting and lying down on request, one could be convinced there is little difference between the socialized wolf and dog. To see that wolf in the presence of a rabbit is to see how much difference there still is: the human is forgotten while the rabbit is relentlessly pursued. A dog near that same rabbit may patiently wait, gazing at his owner, to be permitted to run. Human companions.h.i.+p has become dogs' motivational meat.

MAKING YOUR DOG.

As you choose a new dog from among a litter or a loud shelter of baying mutts and bring him home, you begin to "make a dog" again, recapitulating the history of domestication of the species. With each interaction, with each day, you define-at once circ.u.mscribing and expanding-his world. In the first few weeks with you, the pup's world is, if not entirely a tabula rasa, awfully close to the "blooming, buzzing confusion" that a newborn baby experiences. No dog knows, on first turning his eyes on the person who peeks at him in his shelter cage, what the person expects of him. Many people's expectations, at least in this country, are fairly similar: be friendly, loyal, pettable; find me charming and lovable-but know that I am in charge; do not pee in the house; do not jump on guests; do not chew my dress shoes; do not get into the trash. Somehow, word hasn't gotten to the dogs. Each dog has to be taught this set of parameters for his life with people. The dog learns, through you, the kinds of things that are important to you-and that you want to be important to him. We are all domesticated, too: inculcated with our culture's mores, with how to be human, with how to behave with others. This is facilitated by language, but spoken language is not necessary to achieve it. Instead we need to be alert to what the dog is perceiving and to make our perceptions clear to him.

The first-century Roman encyclopedist Pliny's prodigious Natural History Natural History includes a confident statement of fact about the birth of bears. The cubs, he wrote, "are a white and shapeless lump of flesh, little larger than mice, without eyes or hair and only the claws projecting. This lump the mother bears slowly lick into shape." The bear is born, he was suggesting, as nothing but pure undifferentiated matter, and, like a true empiricist, the mother bear includes a confident statement of fact about the birth of bears. The cubs, he wrote, "are a white and shapeless lump of flesh, little larger than mice, without eyes or hair and only the claws projecting. This lump the mother bears slowly lick into shape." The bear is born, he was suggesting, as nothing but pure undifferentiated matter, and, like a true empiricist, the mother bear makes makes her pup a bear by licking it. When we brought Pump into our home, I felt I was doing just this: I was licking her into shape. (And not just because there was a lot of licking between us-after all, it was exclusively she who was licking.) It was our way of interacting together that made her who she was, that makes dogs that most people want to live with: interested in our goings and comings, attentive to us, not overly intrusive, playful just at the right times. She interpreted the world through acting on it, by seeing others act, by being shown, and by acting with me on the world-promoted into being a good member of the family. And the more time we spent together, the more she became who she was, and the more we were intertwined. her pup a bear by licking it. When we brought Pump into our home, I felt I was doing just this: I was licking her into shape. (And not just because there was a lot of licking between us-after all, it was exclusively she who was licking.) It was our way of interacting together that made her who she was, that makes dogs that most people want to live with: interested in our goings and comings, attentive to us, not overly intrusive, playful just at the right times. She interpreted the world through acting on it, by seeing others act, by being shown, and by acting with me on the world-promoted into being a good member of the family. And the more time we spent together, the more she became who she was, and the more we were intertwined.

Sniff

First sniff of the day: Pump wanders into the living room in the morning while I am dis.h.i.+ng out her food. She's looking sleepy but her nose is wide awake, stretching every which way as though it's doing morning exercises. She reaches her nose toward the food without committing her body, and sniffs. A look at me. Another sniff. A judgment has been levied. She backs from the bowl and forgives me by nosing my outstretched hand, her whiskers tickling while her moist nose examines my palm. We go outside and her nose is gymnastic, almost prehensile, happily taking in smells that gust by ...

We humans tend not to spend a lot of time thinking about smelling. Smells are minor blips in our sensory day compared to the reams of visual information that we take in and obsess over in every moment. The room I'm in right now is a phantasmagoric mix of colors and surfaces and densities, of small movements and shadows and lights. Oh, and if I really call my attention to it I can smell the coffee on the table next to me, and maybe the fresh scent of the book cracked open-but only if I dig my nose into its pages.

Not only are we not always smelling, but when we do notice a smell it is usually because it is a good smell, or a bad one: it's rarely just a source of information. We find most odors either alluring or repulsive; few have the neutral character that visual perceptions do. We savor or avoid them. My current world seems relatively odorless. But it is most decidedly not free of smell. Our own weak olfactory sense has, no doubt, limited our curiosity about what the world smells like. A growing coalition of scientists is working to change that, and what they have found about olfactory animals, dogs included, is enough to make us envy those nose-creatures. As we see see the world, the dog the world, the dog smells smells it. The dog's universe is a stratum of complex odors. The world of scents is at least as rich as the world of sight. it. The dog's universe is a stratum of complex odors. The world of scents is at least as rich as the world of sight.

SNIFFERS.

... Her ungulate-grazing sniff, nose deep in a patch of good gra.s.s, trawling the ground and not coming up for air; the examinatory sniff, judging a proffered hand; the alarm-clock sniff, close enough to my sleeping face to tickle me awake with her whiskers; the contemplative sniff, nose held high in the wake of a breeze. All followed by a half sneeze-just the CHOO, no AH-as though to clear her nostrils of whatever molecule she'd just inhaled ...

Dogs don't act on the world by handling objects or by eyeballing them, as people might, or by pointing and asking others to act on the object (as the timid might); 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 along the caverns of the dog nose. Sniffing is the action of inhaling air, but it is more active than that, usually involving short, sharp bursts of drawing air into the nose. Everyone sniffs-to clear the nose, to smell dinner cooking, as part of a preparatory inhale. Humans even sniff emotively, or meaningfully-to express disdain, contempt, surprise, and as punctuation at a sentence's end. Animals mostly sniff, as far as we know, to investigate the world. Elephants raise their trunk into the air in a "periscope sniff," tortoises slowly reach and open their nostrils wide in a sniff, marmosets sniff while they nuzzle. Ethologists watching animals often take note of all these sniffs, for they may precede an attempt to mate, a social interaction, aggression, or feeding. They record an animal as "sniffing" when it brings its nose close to-but not touching-the ground or an object, or an object is brought close to-but not touching-the nose. In these cases, they are a.s.suming that the animal is in fact inhaling sharply-but they may not be able to get close enough to the animal to see the nostrils moving, or the tiny vortex of air that stirs the area in front of the nose.

Few have looked closely at exactly what happens in a sniff. But recently some researchers have used a specialized photographic method that shows air flow in order to detect when, and how, dogs are sniffing. They have found that the sniff is nothing to be sniffed at. In fact one could make the case that it is neither a single nor a simple inhalation. The sniff begins with muscles in the nostrils straining to draw a current of air into them-this allows a large amount of any air-based odorant to enter the nose. At the same time, the air already in the nose has to be displaced. Again, the nostrils quiver slightly to push the present air deeper into the nose, or off through slits in the side of the nose and backward, out the nose and out of the way. In this way, inhaled odors don't need to jostle with the air already in the nose for access to the lining of the nose. Here's why this is particularly special: the photography also reveals that the slight wind generated by the exhale in fact helps to pull more of the new scent in, by creating a current of air over it.

This action is markedly different from human sniffing, with our clumsy "in through one nostril hole, out through the same hole" method. If we want to get a good smell of something, we have to sniff-hyperventilate, inhaling repeatedly without strongly exhaling. Dogs naturally create tiny wind currents in exhalations that hurry the inhalations in. So for dogs, the sniff includes an exhaled component that helps the sniffer smell. This is visible: watch for a small puff of dust rising up from the ground as a dog investigates it with his nose.

Given our tendency to find so many smells disgusting, we should all celebrate that our olfactory system adapts to an odor in the environment: over time, if we stay in one place, the intensity of every smell diminishes until we don't notice it at all. The first smell of coffee brewing in the morning: fantastic ... and gone in a few minutes. The first smell of something rotting under the porch: nauseating ... and gone in a few minutes. The sniffing method of dogs enables them to avoid habituation to the olfactory topography of the world: they are continually refres.h.i.+ng the scent in their nose, as though s.h.i.+fting their gaze to get another look.

THE NOSE NOSE.

I crack open her window in the car-just enough to fit a dog-sized head (remembering the time she threw herself completely out the open window after that squirrel hitchhiking on the side of the road). Pump props herself up on the armrest and pokes her muzzle out of the car as we race along in the night. She squints her eyes tight, her face is streamlined in the wind, and she projects her nose deep into the rus.h.i.+ng air.

Once a smell has been vacuumed in, it finds a receptive welcome from an extravagance of nasal tissue. Most purebreds, and nearly all mutts, have long muzzles in whose noses are labyrinths of channels lined with special skin tissue. This lining, like the lining of our own noses, is primed to receive air carrying "chemicals"-molecules of various sizes that will be perceived as scents. Any object we encounter in the world is cast in a haze of these molecules-not only the ripe peach on the counter but the shoes we kick off at the door and the doork.n.o.b we grasp. The tissue of the inside of the nose is entirely blanketed with tiny receptor sites, each with soldiers of hairs to help catch molecules of certain shapes and pin them down. Human noses have about six million of these sensory receptor sites; sheepdog noses, over two hundred million; beagle noses, over three hundred million. Dogs have more genes committed to coding olfactory cells, more cells, and more kinds kinds of cells, able to detect more kinds of smells. The difference in the smell experience is exponential: on detecting certain molecules from that doork.n.o.b, not single sites but combinations of sites fire together to send information to the brain. Only when the signal reaches the brain is it experienced as a scent: if it is we doing the sniffing, we'd say of cells, able to detect more kinds of smells. The difference in the smell experience is exponential: on detecting certain molecules from that doork.n.o.b, not single sites but combinations of sites fire together to send information to the brain. Only when the signal reaches the brain is it experienced as a scent: if it is we doing the sniffing, we'd say A-ha! I smell it. A-ha! I smell it.

More than likely, though, we won't smell it. But the beagle will: it's been estimated that their sense of smell may be millions of times more sensitive than ours. Next to them 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: two Olympic-sized pools full.*

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. The flesh of the petals, plump with moisture compared to that of the leaf, holds a different odor besides. The fold of a leaf has a smell; so does a dewdrop on a thorn. And time time is in those details: while we can see one of the petals drying and browning, the dog can smell this process of decay and aging. Imagine smelling every minute visual detail. That might be the experience of a rose to a dog. is in those details: while we can see one of the petals drying and browning, the dog can smell this process of decay and aging. Imagine smelling every minute visual detail. That might be the experience of a rose to a dog.

The nose is also the fastest route by which information can get to the brain. While visual or auditory data goes through an intermediate staging ground on the way to the cortex, the highest level of processing, the receptors in the nose connect directly to nerves in specialized olfactory "bulbs" (so shaped). The olfactory bulbs of the dog brain make up about an eighth of its ma.s.s: proportionally greater than the size of our central visual processing center, the occipital lobes, in our brains. But dogs' specially keen sense of smell may also be due to an additional way they perceive odors: through the vomeronasal organ.