Inside of a Dog: What Dogs See, Smell, and Know (7 page)

From results like these comes the notion that there is a cognitive difference between wolves and dogs: usually, that wolves are insightful problem solvers, and dogs simpletons. In actual fact, historically theories have oscillated between claiming dogs to be more intelligent, or wolves to be the smarter of the two. Science is often contingent on the culture in which it is practiced, and these theories reflect the then-prevailing ideas about animal minds. The accumulated data of dog and wolf behavior, though, leads to a more nuanced position. Wolves seem to be better at solving certain kinds of
physical
puzzles. Some of this skill is explainable by looking at their natural behavior. Why did wolves readily learn the rope-pulling task? Well, they do a lot of grabbing and pulling on things (like prey) in their natural environment. Some of the difference can be traced to dogs' more limited requirements for living. Having been folded into the world of humans, dogs no longer need some of the skills that they would to survive on their own. As we'll see, what dogs lack in physical skills, they make up for in people skills.

There is a final, seemingly minor difference between the two species. This one small behavioral variation between wolves and dogs has remarkable consequences. The difference is this: dogs look at our eyes.

Dogs make eye contact and look to us for information—about the location of food, about our emotions, about what is happening. Wolves avoid eye contact. In both species, eye contact can be a threat: to stare is to assert authority. So too is it with humans. In one of my undergraduate psychology classes, I have my students do a simple field experiment wherein they try to make and hold eye contact with everyone they pass on campus.

Both they and those on the receiving end of their stares behave remarkably consistently: everyone can't wait to break eye contact. It's stressful for the students, a great number of whom suddenly claim to be shy: they report that their hearts begin to race and they start sweating when simply holding someone's gaze for a few seconds. They concoct elaborate stories on the spot to explain why someone looked away, or held their gaze for a half second longer. For the most part, their staring is met with deflected gazes from those they eyeball. In a related experiment, they test gaze in a second way, verifying our species' tendency to follow the gaze of others to its focal point. A student approaches any publicly visible and shared object—a building, tree, spot on the sidewalk—and looks fixedly at one point on it. Her partner, another student, stands nearby and surreptitiously records the reactions of passersby. If it's not rush hour and raining, they report finding that at least some people stop in their tracks to follow their gaze and stare curiously at that fascinating sidewalk spot: surely there must be
something.

If this behavior is unsurprising, it is because it is so human: we look. Dogs look, too. Though they have inherited some aversion to staring too long at eyes, dogs seem to be predisposed to inspect our faces for information, for reassurance, for guidance. Not only is this pleasing to us—there is a certain satisfaction in gazing deep into a dog's eyes gazing back at you—it is also perfectly suited to getting along with humans. As we will see later in this book, it also serves as a foundation for their skill at social cognition. We not only avoid eye contact with strangers, we rely on eye contact with intimates. There is information in a furtive glance; a gaze mutually held feels profound. Eye contact between people is essential to normal communication.

Hence a dog's ability to find and gaze at our eyes may have been one of the first steps in the domestication of dogs: we chose those that looked at us. What we then did with dogs is peculiar. We began designing them.

The label on her cage said "Lab mix." Every dog in the shelter was a Lab mix. But surely Pump was born of a spaniel: her black, silky hair fell against her slender frame; her velvet ears framed her face. In sleep she was a perfect bear cub. Soon her tail hairs grew longer and feathery: so she's a golden retriever. Then the gentle curls on her underbelly tightened; her jowls filled a bit: okay, she's a water dog. As she ages her belly grows until she has a solid, barrel-like shape—she's a Lab after all; her tail becomes a flag needing trimming—a Lab/golden mix; she could be still one moment and sprinting the next—a poodle. She is curly and round-bellied: clearly the product of a sheepdog who'd snuck into the bushes with a pretty sheep. She's her own dog.

The original dogs were mongrels, in the sense that they didn't come from a controlled lineage. But many of the dogs we keep, mutts or not, emerged from hundreds of years of strictly controlled breeding. The consequence of this breeding is the creation of what are nearly subspecies, varying in shape, size, lifetime, temperament,* and skills. The outgoing Norwich terrier, ten inches high and ten pounds strong, is but the weight of the calm, sweet, enormous Newfoundland's head. Ask some dogs to retrieve a ball and you get a puzzled look; but a border collie doesn't need to be asked twice.

The familiar differences between modern breeds aren't always the result of intentional selection. Some behaviors and physical features are selected for—retrieving prey, smallness, a tightly curled tail—and some just come along for the ride. The biological reality of breeding is that the genes for traits and behaviors come in clusters. Mate a few generations of dogs with particularly long ears and you might find that they all share other characteristics: a strong neck, downcast eyes, fine jowls. Coursing dogs, bred to gallop swiftly or long, are leggy—their leg length matches (in the husky) or surpasses (in the greyhound) the depth of their chests. By contrast, dogs who track on the ground (as the dachshund) wound up with legs much shorter than their chest is deep. Similarly, selecting for one particular behavior inadvertently selects for accompanying behaviors. Breed dogs who are very sensitive to motion—who probably have an overabundance of rod photoreceptors in their retinae—and you may also get a dog whose acute sensitivity to motion leads to their being temperamentally high-strung. Their appearance might change, too: they may have large, globular eyes for seeing at night. Sometimes what comes to be desirable in a breed is a trait that first appeared inadvertently.

There is evidence of distinct dog breeds as early as five thousand years ago. In drawings from ancient Egypt, at least two kinds of dogs are depicted: mastiff-looking dogs, big of head and body, and slim dogs with curled tails.* The mastiffs may have been guard dogs; the slender dogs appear to have been hunting companions. And so the designing of dogs for particular purposes began—and continued along these lines for a long while. By the sixteenth century, there were added other hounds, bird dogs, terriers, and shepherds. By the nineteenth century, clubs and competitions sprouted, and the naming and monitoring of breeds exploded.

The various modern breeds have probably all emerged with this proliferation of breeding in the last four hundred years. The American Kennel Club now lists nearly one hundred fifty varieties, grouped according to the purported* occupation of the breed. Hunting companions are distributed into "sporting," "hound," "working," and "terrier" categories; there are, in addition, the working "herding" breeds, the plainly "nonsporting" breeds, and the rather self-explanatory "toys." Even among dogs bred to join the hunt, there are subdivisions, by the very kind of assistance they provide (pointers point out the prey; retrievers retrieve it; Afghan hounds exhaust it); by the specific prey they're after (terriers are ratters, and harriers go after hares); and by the medium preferred (beagles chase on land; spaniels will swim in water). Worldwide, there are hundreds more breeds still. Breeds vary not just by our uses of them but physically: by body size, head size, head shape, body shape, type of tail, coat kind, coat color. Go searching for a purebred dog and you'll confront a new-car-worthy list of specs, detailing everything from the ears to the temperament of your future pup. Want a long-limbed, short-haired, jowly dog? Consider the Great Dane. In more of a short-nosed, rolled-skin, curly-tailed kind of mood? Here's a nice pug for you. Choosing between breeds is like choosing between anthropomorphized option packages. You not only get a dog, you get one who is typically "dignified, lordly, scowling, sober and snobbish" (shar-pei); "merry and affectionate" (English cocker spaniel); "reserved and discerning with strangers" (chow chow); with a "rollicking personality" (Irish setter); full of "self-importance" (Pekingese); having "heedless, reckless pluck" (Irish terrier); "equable" (Bouvier des Flandres); or, most surprisingly, "a dog at heart" (briard).

The dog fanciers will be surprised to hear, perhaps, that the grouping of breeds based on genetic similarity does not result in the same groupings as the AKC. Cairn terriers are closer to hounds; shepherds and mastiffs share much of their genomes. The genome belies most people's assumptions about dogs' similarities to wolves, too: the long-haired, sickle-tailed huskies are closer to wolves than the long-bodied, skulking German Shepherd. Basenjis, who bear almost no physical resemblance to wolves, are closer still. This is yet another indication that, for most of their domestication, the dog's appearance was an accidental side effect of his breeding.

Dog breeds are relatively closed genetic populations, meaning that each breed's gene pool is not accepting new genomes from outside the pool. To be a member of a breed, a dog must have parents who are themselves members. Thus any physical changes in the offspring can only come from random genetic mutations, not from the mixing of different gene pools that usually occurs when animals (including humans) mate. Mutations, variation, and admixtures are generally good for populations, though, and help to prevent inherited disease: this is why purebred dogs, though they come from what is considered "good stock" in that the ancestry of the dogs is traceable through the breeding line, are more susceptible to many physical disorders than are mixed-breed dogs.

One boon of a closed gene pool is that the genome of a breed can be mapped, and in fact it recently has: a boxer's genome was the first, around nineteen thousand genes' worth. As a result, scientists are starting to make an accounting of where on the genome the genetic variations are that lead to characteristic traits and disorders, such as narcolepsy, the sudden and total fall into unconsciousness to which some dog breeds (particularly Dobermans) are susceptible.

Another advantage of a closed gene pool of a breed discussed by researchers is that it feels as though one is getting a relatively reliable animal when one selects from it. One can pick a "family-friendly" dog or one advertised as a skillful house guardian. But it is not so simple: dogs, like us, are more than their genome. No animal develops in a vacuum: genes interact with the environment to produce the dog you come to know. The exact formulation is difficult to specify: the genome shapes the dog's neural and physical development, which itself partially determines what will be noticed in the environment—and whatever is noticed itself further shapes continued neural and physical development. As a result, even with inherited genes, dogs aren't just carbon copies of their parents. On top of this, there is also great natural variability in the genome. Even a cloned dog, should you be tempted to replicate your beloved pet, will not be identical to the original: what a dog experiences and whom he meets will influence who he becomes in innumerable, untraceable ways.

So although we have tried to design dogs, the dogs we see today are partly creatures of serendipity.
What breed is she?
is a question I've been asked about Pump more than any other—and I in turn ask of other dogs. Her mongrelness encourages the great game of guessing her heritage: the resulting hunches are satisfying, even though none could ever be verified.*