The Canidae family of wolf-like creatures has been around for over 30 million years, while the subspecies of dog (canis lupus familiaris) has only been with us for around 20,000 years, so most of a dog's being and behavior is wolf-like.  The sight of a nearby squirrel when on a walk is often enough to pierce the thin veil of domestication and reveal the wolf-like nature of your canine friend.   In this chapter we'll look at the dog senses, behaviors and sense of time that derive from their wolf cousins.  Next week we'll look at those behaviors and abilities unique to dogs that have arisen and been selected for through their relationship with people.

This chapter and the next borrow heavily from two books:

The Genius of Dogs: How Dogs are Smarter Than You Think by Brian Hare and Vanessa Woods.  Brian Hare is one of the country's leading expert in canine cognition and is a professor in Evolutionary Anthropology, and Psychology and Neuroscience at Duke University.

Inside of a Dog: What Dogs See, Smell, and Know by Alexandra Horowitz.  Horowitz heads the dog cognition lab at Barnard College.

Canine Senses

Smell

We tend to anthropomorphize animals, interpreting their behavior through the lens of human behaviors.  But in doing so, we blind ourselves to the incredible world that other animals inhabit. Humans live in a world dominated by vision; by contrast, dogs live in a world dominated by smell.  Dogs have around 40 times the number of olfactory receptors than humans: six million cells in humans spread over an area the size of a postage stamp as compared to 300 million for a beagle spread over an area the size of a handkerchief.  The olfactory lobes in a dog's brain make up about one eighth of a dog's brain, proportionately more than the vision centers of the human brain.  To what purpose do dogs use their prodigious sense of smell?  John Bradshaw, in his book In Defence of Dogs, says "Smells are very important to dogs, much more so than they are to us.  Dogs use odor not just to decide what to eat and what not to: odor is their primary means of identifying people, places and other dogs.  Smell is their dominant sense, the one they use in preference to all their other senses, whenever they can."  Wolves use their sense of smell to identify and track their prey.  Wolves and dogs also use scent as a primary method of communication: marking territory and advertising their presence to other canines.

The dog's sense of smell is truly remarkable.  Dogs can detect the odor of a single fingerprint on a piece of glass that was left outside for a week.  Trained dogs can detect the unique smell from people with skin, colorectal, breast, lung and prostate cancers.  Dogs can smell seizures in epileptics before they happen, they can detect dropping blood sugar in people with diabetes, and they can detect covid.  

When wolves or dogs track prey, they crisscross an area until they pick up a scent, then they follow the combination of air scent and ground scent.  Since scents fade with time, dogs can detect the time and direction that their prey was moving by following increasing concentrations of odors.  People and animals under stress give off distinctive odors, which help the dog track the specific prey being chased.

The wet nose of a dog may help them capture scent molecules which travel to their vomeronasal organ, which, as in the cat,  specializes in identifying pheromones and specialized scents from other dogs.

It used to be thought that dogs marked with urine to outline their territory.  However, it appears that male or female urine marking is used to give information about female sexual readiness and male social confidence.  As Horowitz says, "marking seems to leave information about who the urinator is , how often he walks by this spot in the neighborhood , his recent victories , and his interest in mating . In this way , the invisible pile of scents on the hydrant becomes a community center bulletin board , with old , deteriorating announcements and requests peeking out from underneath more recent posts of activities and successes . Those who visit more frequently wind up being at the top of the heap : a natural hierarchy is thus revealed . But the old messages still get read , and they still have information — one element of which is simply their age."  

Scat also provides a unique olfactory signal identifying the owner through secretions from dogs' anal sacs.  The vigorous scratching with back feet that dogs sometimes do may add a visual cue and perhaps an additional odor from glands on the pads of the feet.

Scent signaling is part of the social behavior of dogs and wolves.  If no other dogs are around, male dogs will stop lifting their legs and both male and female dogs will void their bladders without bothering to deposit just a small amount.

Vision

Compared to humans, canine visual perception is poor, with one poodle's eyesight measured at 20/75.   It's not because they need corrective lenses, it's because their eyes are different from humans.  Among mammals, only primates have a fovea that gives sharp detail to whatever they're looking at.  Dogs have a visual streak with a dense horizontal band of photoreceptors that gives them sharp vision across the center of their visual field, but not as sharp as human sight.   

Like cats, dogs' eyes are optimized for hunting in low light conditions.  They have a wider field of view than humans and their eyes are tuned to detect motion.   I'm often surprised at how my dog will not see a rabbit sitting motionless on our lawn, but if that rabbit starts to move, my dog is off like a shot.  My dog also can't recognize me if I'm outside standing still, but she can tell that it's me by my gait.

Hearing

Again, like cats, dogs can hear much higher frequencies than humans, 45-60KHz vs 15-20kHz.  This, plus their upright, swivelable ears (for those dogs without floppy ears) allow them to localize sounds and hear at about four times the distance that humans can.

Touch

Just as with human infants, the sense of touch is critical to developing puppies to help form emotional attachments with the pup's mother, and as that emotional bond is transferred to the dog's owner, appropriate petting can help maintain the emotional bond.  Like cats, dog's whiskers are a specialized sense organ that help dogs sense air currents and navigate in low light conditions.

Taste

Dogs have an average of 1,700 taste buds, intermediate between 475 of the obligate carnivore cats and 9,000 of the omnivore humans.  Dogs have the same five receptor types as humans (sweet, sour, bitter, salty and umami) but they also have a sixth taste receptor for water, which is on the tip of their tongue which scoops up water when they drink.  It is theorized that this receptor helps drive the thirst reflex to keep their electrolytes in balance, or maybe it just helps them lap up water.

Canine Memory and Sense of Time

I used to think, when I saw my dog staring at me, that she was thinking what a bad owner I was, for not having taken her our to play.  However, after doing some research for this course, I realize that dogs are incapable of thinking like that.  Firstly, dogs don't use language the way we do.  Our brains are full of running monologues, ruminating about the past, the future, what people did and what we're going to eat.  Dogs, and other animals don't have that running monologue; they're little Zen masters; without language their minds are open to experience.

Furthermore, they live primarily in the here and now.  Studies have been made of episodic memory in humans and animals, that is, the ability of animals to remember an arbitrary event without emotional valence.  For example, when humans are given some random words to remember, like Person, Woman, Man, Camera, TV,  those with a good brain can recall that sequence of words, sometimes for hours or even days later.  In a delayed matching to sample test, animals are tested by showing them an arbitrary symbol and then within a short time showing several different symbols.  If they pick the symbol that was shown previously, by perhaps pressing a lever, they get a reward.  Across all animals studied except humans, episodic memory lasts for a very short time, seconds to minutes; dogs' ability to remember an arbitrary event decays to zero after about two minutes while humans can recall for two days or more.   In an interesting National Geographic article, the author of a study said, "The data tell us that animals have no long-term memory of arbitrary events (episodic memory). Based on the new study, we think humans' ability to remember arbitrary events is unique."

This is not to say that dogs or other animals cannot remember anything for any length of time.  Dogs and other animals have excellent associative memories, where they associate situations that have emotional valence with their associated emotions.  For example, when you pick up the dog's leash, your dog gets excited because it anticipates going for a walk.  Or if a person struck a dog with their hand, the dog will experience fear at the sight of that person or at a raised hand.  Dog training harnesses associative memory through operant conditioning: you say sit, and give a dog a treat when she sits, and she'll quickly associate a reward with sitting on command.  However, your dog may be wonderfully trained in the living room and completely forget her training when in the dog park because she associated the commands with the living room, not the dog park.   And if you come home and punish your dog for having had an accident in the house, she'll have no idea why she's being punished because she lives in the here and now and doesn't remember soiling your rug.

Part of a dog's sense of time is their circadian rhythm.  If they are on a strict routine they can know when it's time to get up, when it's time to go to bed, what time to eat and when to go out.  We have the same capacity, as long as we're on a strict routine we can anticipate the alarm clock almost to the minute.  But that anticipation is hardwired into our brains, it doesn't take a lot of thinking.

Associative memory is a very powerful guide to getting along in the world.  As Alexandra Horowitz says, "Dogs certainly remember a large amount: they remember their owners, their homes, the place they walk. They remember innumerable other dogs, they know about rain and snow after experiencing them once; they remember where to find a good smell and where to find a good stick. They know when we can’t see what they are doing; they remember what made us mad last time they chewed it up; they know when they are allowed on the bed and when they are forbidden from it. They only know these things because they have learned them — and learning is just memory of associations or events over time."  We can't really know what our pets are thinking, but I think it's best to imagine that they're mindfully always living in the present, reacting to events as they occur.

Canine Behaviors

When trying to understand our dog, it may be helpful to consider that nearly all dog behaviors are derived from their wolf ancestors.  The modern grey wolf is probably different from dogs' (Siberian?) wolf ancestor, but the grey wolf can still give us insights into the origins of dog behaviors.  Grey wolves live in packs, with a mating pair and several generations of offspring.  Typical pack sizes range from four to twenty, sometimes growing in the winter with mostly related wolves to hunt larger prey.   Grey wolves are very social, and divide up the work of hunting, raising younger pups and defending their territory against neighboring wolf packs.  As Alexandra Horowitz says, "wolves do have features that made them terrific candidates for artificial selection. The process favors a social animal who is behaviorally flexible, able to adjust its behavior in different settings. Wolves are born into a pack, but only stay until they are a few years old: then they leave and find a mate, create a new pack, or join an already existing pack. This kind of flexibility to changing status and roles is well suited to dealing with the new social unit that includes humans. Within a pack or moving between packs, wolves would need to be attentive to the behavior of packmates — just as dogs will need to be attentive to their keepers and sensitive to their behavior. Those early wolf - dogs meeting early human settlers would not have benefited the humans much, so they must have been valued for some other reason — say, for their companionship. The openness of these canids allowed them to adjust to a new pack: one that would include animals of an entirely different species."

Dog Kisses

Does your dog jump up and lick you when you come home?  That's instinctive; when wild canid mothers return to the den, the puppies lick her muzzle in order to get her to regurgitate food for them.  Fido probably doesn't care that you never vomit up a piece of rabbit.  As Horowitz says, "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. Mothers not only clean their pups by licking, they often give a few darting licks when reuniting after even a brief time apart. A younger or timid dog may lick the muzzle, or muzzle vicinity, of a bigger, threatening dog to appease him. 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."

Canine Socialization Period

Last week we saw how the period between two and nine weeks of life is critical for a kitten to explore and become familiar with its environment.  Dog puppies have a similar critical socialization period between three and eleven weeks of age where they become familiar with their environment and other animals.  This is a much longer time period than for wolf pups; wolf pups stay in their den until they are three weeks old and then come out and meet the rest of the pack.  Shortly after that they become fearful of all new animals that the wolf pups meet.  The longer socialization period in puppies, and neotenization in general allows dogs to see humans as attachment figures, based on a parent-offspring relationship.  Dogs continue to have a juvenile period through about one year of age, where they are very open to learning about the world and what strategies work best.  As a dog gets older, its ability to cope with change will gradually diminish.

Play

As wolf pups enter their juvenile period, they engage in play with their littermates: pouncing on pretend prey objects and attacking and chasing each other.  Some wolf pups have even been seen playing fetch.  This is a key part of wolf socialization, where they practice relating to each other as well as develop hunting and fighting skills.  Play in wolves subsides as they move into adulthood.  In contrast, dogs continue to engage in play most of their life.  As we'll see next week, research by Alexandra Horowitz has shown that dog play is highly scripted ritualized combat, with great care taken to see that neither combatant gets hurt.  It is also very rewarding to dogs, generating increased dopamine and oxytocin in their bloodstream.

Canine Communication: Vocalizations

We've looked at how wolves and dogs use scent to communicate over distances.  Wolves also use vocalizations and body language to communicate amongst themselves.  Wolves growl as an aggressive or defensive warning or to signify dominance.  Wolves howl together, often before or after a hunt, as a statement of pack solidarity.  Wolves yip, whine and wimper, often to signify submission to dominant wolves.  Wolves can kind of bark, although very seldom, and usually as an alarm when they sense danger.   You can hear different wolf vocalizations on this web site.

Dog barking seems to be a by-product of domestication, because domesticated foxes bark while wild ones don't.  Brian Hare describes how dogs use different barks and growls to communicate different things:  "In one experiment, researchers recorded a “food growl” where a dog was growling over food, and a “stranger growl” where a dog was growling at the approach of a stranger.  The researchers played these different growls to a dog who was approaching a juicy bone.  The dogs were more hesitant to approach if they heard the food growl rather than the stranger growl.  In another experiment, researchers recorded “alone barks” of dogs when they were alone, and “stranger barks” when a stranger was approaching .  When researchers played three “alone barks” to different dogs, these dogs showed less attention to each bark.  But when they played the fourth bark, the “stranger bark",  the dogs quickly jumped to attention. They did the same thing when the barks were reversed, showing that dogs could clearly distinguish between the two types of barks. Using a similar test, the dogs also distinguished between the barks of different dogs.

How well do people understand what dogs are saying?  Researchers played a collection of barks to a group of people. Regardless of whether they owned a dog or not, most people could tell from a bark whether a dog was alone or being approached by a stranger, playing or being aggressive.  Unlike dogs, people were not very skilled at discriminating between different dogs. The only time people could tell between different dogs was when they heard the “stranger bark ".   This is the exact moment a dog owner would be most likely to want to understand the meaning of a dog bark, since strangers can mean trouble."

In 1947 Rudolph Schenkel wrote a paper studying the behavior of wolf packs.  He popularized the notion that wolves within a pack fought for dominance, the winner becoming the alpha male.  Wolf researcher David Mech relied on Schenkel's research when he published a seminal book on wolf behavior in 1968.  However, he now regrets helping to popularize the notion of wolf competition and has requested that the book publisher stop printing the book.

The problem with Schenkel's research is that it was done on unrelated wolves which had been captured and kept in a small area under stressful conditions, which led to continued fights between the captive wolves.  It was as if aliens had published a book on the behavior of human families by studying inmates in a Supermax prison.  In  the wild, a pack of wolves will not fight amongst each other.  They consist of a breeding pair of wolves and their offspring; they are a closely related family.  In the videos above, you may have seen displays of dominance and submission, but these are normal behaviors designed to reinforce pack structure and unity, not fights for dominance between members of the pack.  Wolves are extremely aggressive, much more so than their domesticated dog cousins.  At least 60% of wolf deaths in Denali park in Alaska are caused by other wolves, but these are always between wolf packs or attacks by a pack on an outsider wolf.  Displays of dominance or submission between members of a wolf pack are an adaptation to prevent intrapack violence; by reinforcing pack hierarchy.

Unfortunately, the idea that dogs are constantly vying to increase their status within a pack has affected several generations of dog trainers such as Cesar Milan, who promote the idea that human owners must show their dominance over the dogs by forcing them to submit, sometimes using violence and always showing them who is boss.   For an pet that is hardwired to form strong parent-child type attachments, hitting them and forcing submission is analogous to child abuse: it stresses the animal and can lead to more behavior problems.  Horowitz says, "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."  Or maybe we can get them to do things for us because they love us so much.  That's the subject of next week's discussion.

How does this material help inform your view of your dog?  What behaviors do you still find curious?  Please come to class prepared to discuss your personal experience with canis lupus familiaris.