Wellness: Food & Nutrition
A vet speaks out on genetically modified pet food.
Most dogs now dine on some type of genetically modified (GM) food, often in the form of corn and soy in their kibble. As these ingredients increasingly enter the food supply, we have one more reason to wonder if our shopping choices might be harming our pets.
More animal feeding studies are needed, experts say, and a recent long-term, peer-reviewed report points out why. It found that a diet of GM corn and soy led to higher rates of severe stomach inflammation in pigs, which are physiologically similar to dogs.
Robert Silver, DVM, a Boulder, Colo., holistic vet, tackled the issue earlier this year when he presented his paper, “Genetically Modified Food and Its Impact on Pet Health” at the American Holistic Veterinary Medical Association conference in Kansas City, Mo. Why did he choose this controversial topic, one that few vets even acknowledge?
Silver—a pioneer in the field of holistic veterinary medical practice—says he was inspired by a seminar he attended in Boulder on GM foods and human health. The speakers included Don Huber, a Purdue University professor, and activist Jeffrey Smith, who discussed problems, including reproductive difficulties, that have occurred in livestock fed GM crops.
“I found this seminar mind-opening,” says Silver, the lone vet in attendance. “I had always believed the PR about GM foods—that they are going to feed the world and are a good outcome of our genetic technology.”
The Food and Drug Administration, which regulates the safety of GM crops consumed by humans and animals, considers most GM plants “substantially equivalent” to traditional plants and “generally recognized as safe.” Their regulation involves a voluntary consultation process with the developer before products are brought to market.
Smith, founder of the Institute for Responsible Technology, disagrees. On its website (responsibletechnology.org), he warns that “nearly all GM crops are described as ‘pesticide plants.’ They either tolerate doses of weed killer, such as Roundup, or produce an insecticide called Bt-toxin. In both cases, the added toxin—weed killer or bug killer—is found inside the corn or soybeans we consume.”
Silver says that while “allergies, GI problems, increased risk of cancer, neurodegenerative conditions” and other ills could all be, in part, related to GM foods, “there is no objective evidence of this yet” in dogs. “However, all vets will agree that there has been an uptick in [these diseases] in the past 10 to 20 years.” The advent of GM foods in the 1990s “fits into this timing of disease increases,” he says.
His presentation referred to studies that raise doubt about the safety of biotech crops, such as one reported in 1996 in the New England Journal of Medicine, which found that genes inserted into crops can carry with them allergenic properties.
Silver says that genetic modification introduces foreign proteins that may encourage allergies, and the widely planted Bt corn, which makes its own insecticide, “could possibly cause leaky gut, the gateway to chronic disease.” Corn is a major component of most commercial pet foods. “The big problem with commercial foods is that they are manufactured at high temperatures and pressures,” which alters them and makes them “potentially more allergenic.” And commercial foods contain industrial ingredients that are “more likely to contain GM and herbicide contaminants.”
A study published last year found that GM crops engineered to withstand the toxic herbicide Roundup must now be doused with even more herbicide, since weeds have also developed resistance to it. Residues of these chemicals on crops can find their way into pet food.
A 2013 study published in the science journal Entropy reports that the heavy use of Roundup could be linked to Parkinson’s, autism, infertility and cancers. It goes on to report that residues of Roundup in food can interact with, and enhance, the damaging effects of other environmental toxins. “Negative impact on the body is insidious and manifests slowly over time as inflammation damages cellular systems throughout the body,” the study’s researchers say.
According to Silver, heightened sensitivity to dietary ingredients “is probably what we are seeing with GM foods. It is of concern that this may be driving the increase in GI problems in pets.” Although gluten probably does account for some problems with grain consumption, “I think that grain-free diets, if they are also soy free and contain protein from animals not fed GM crops, can help many dogs, due to being GM free—and not due to some allergy or gluten issue.”
To a holistic doctor, food is medicine, and Silver strongly recommends home meal preparation from individually sourced ingredients to avoid feeding GM ingredients, especially to pets who have other health problems. “I am truly a holistic practitioner in that I believe an ounce of prevention is worth a pound of cure.”
Benbrook, C.M. 2012. Impacts of genetically engineered crops on pesticide use in the U.S.—the first 16 years. Environmental Sciences Europe 24: 24.
Ordlee, J., et al. 1996. Identification of a Brazil-nut allergen in transgenic soybeans. The New England Journal of Medicine 334: 688–692.
Samsel, A., and S. Seneff. 2013. Glyphosate’s suppression of cytochrome P450 enzymes and amino acid biosynthesis by the gut microbiome: Pathways to modern diseases. Entropy 15 (4): 1416–1463.
Good Dog: Studies & Research
How to approach future research
“Yes, that’s just how it is with my dog, too!”
“Everybody knew that before reading about it.”
“I figured I wasn’t the only one who felt that way about my dog.”
These are common responses to stories about the many research papers investigating the relationship between people and dogs. Most of us read the latest scientific findings with a great sense of happiness and validation. Our relationship with dogs is very much like our relationship with our children? Yep. Our dogs consider their guardians to be extra special and emotionally important? Whew, thought so. Our attachment to our dogs provides us with many benefits? Duh. Being a helicopter parent does not cause the damage to fur kids that it can to human kids? Yay! Gazing into our dog’s eyes can enhance the feelings of true love between us? Awww.
It’s exciting that there has now been enough research into attachment between people and dogs and the bonds they have for one another to prompt a review paper to suggest where to go from here. The recently published “Measuring dog-owner relationships: Crossing boundaries between animal behaviour and human psychology ” summarizes what we know and discusses what should be studied next as well as how. That means we can all happily anticipate more revelations that will further confirm the many details about what we know: Humans and dogs are close in wonderful ways that benefit us both. In the introduction to the paper, the authors say, “In this review, we propose that the next step in anthrozoology [study of interactions between humans and other animals] research is to use all the potential information within attachment theory, to reveal whether or not different types of relationship styles exist among different dog-owner dyads and how they might be identified. Furthermore, we give suggestions for which factors may contribute to the development of different attachment styles in dogs, hence deserving more attention in future studies of the dog- human relationship.” What this means is that there is a wealth of information about relationships between humans and the styles of connection that people have with one another that can be used to inform future research on the ways that dogs and people forms bonds to one another.
Some suggestions that these authors have are to focus on both dogs and people simultaneously rather than just one side of the relationship. They also recommend investigating physiological as well as behavioral responses to situations (such as separation and reunions) that are often the focus of attachment studies. They encourage addressing both the attachment style of individual dogs and the caregiving style of individual people to help pairs avoid any conflicts that have plagued them in the past and to help them form the best, most positive relationships in the future.
What are you most interested in knowing about the science of your relationship with your dog?
News: Guest Posts
Well, it looks like recent research into prehistoric Japanese graves proves, at least, that dogs were indeed our long-time hunting companions. In this fascinating study written by Angela Perri recently published a fascinating study that proves just this. This line of inquiry started when she was a grad student at Durham University in the UK. As David Grimm writes in Science:
“She wanted to get a sense of how dogs may have aided early humans in taking down game, so she did her best to approximate the activity: In 2011, she joined a group of Japanese businessmen on a wild boar hunt in a dense forest near Hiroshima. ‘It was terrifying,’ says Perri, now a zooarchaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. ‘The boar sound like a train. They’re very aggressive, and they have big tusks. At any moment, one could come charging at you.’”
But the biggest takeaway she got was just how impressive the dogs were during this hunt. Not only did the 5 Bloodhounds and Shiba Inus help to track down the prey, but they also warned the humans when the boars were nearby.
That got Perri interested in investigating Japanese research papers for anything about dogs and the Jōmon culture—hunter-gatherers from 16,000 to 2,400 year ago. They lived in the northern islands with a cold climate filled with large terrestrial megafauna of the Pleistocene, like Naumann’s elephants and Yabe’s giant deer. But during the Holocene, 10,000 to 12,000 years ago, there was a climatic warming displacing the larger animals with smaller, quicker ungulates like sika deer and wild boar. As Perri notes in the Antiquity paper, “This environmental shift … led to the creation of new exploitation niches for Jōmon foragers, including important variations in plant availability, coastal resources and terrestrial prey species.”
Perri’s research has involved studying dogs as “hunting technology,” and as she noted, “A hunting partnership between dogs and humans has long been postulated in the archaeological literature, with some researchers suggesting that such a collaborative alliance was the basis for the initial domestication of dogs. She points out that, “Dogs are an important, and in some cases indispensable, hunting aid for many modern forager groups, as they probably were for foragers in prehistory.” And explains that, “Injured deer often run, leading hunters on long chases, and wild boar can be aggressive and quickly learn to evade capture. Hunting dogs mitigate these factors by tracking blood trails, forcing game into vulnerable positions (e.g. in water) and holding prey until the hunter can make the final kill.”
Perri was familiar with the significance that dogs had with many ancient cultures, and how the ethnographic record has confirmed their importance and the revered status many of the dogs obtained, which often was displayed in the manner they were buried in “remarkably human-esque ways, often with grave goods and markers.”
She performed a comprehensive survey of Japanese archaeological literature, and found that the Honshu Jōmon did bury their canine hunting partners in shell middens, same as they did with humans. And found over 110 canine burials from 39 archaeological sites. “They were treating their dogs the same way they treated their human hunters.” And, “Like people, the dogs (which may have resembled Shiba Inus) were placed singly and appear to have been arranged in particular postures. ‘They looked like they curled up and went to sleep,’ Perri notes. Some had suffered what appeared to be hunting injuries—broken legs and teeth—and many of their bones had healed, suggesting people had taken care of them. Some were also found with grave goods, like shell bracelets and deer antlers.” Their ages ranged from newborn to over 12 years old. While the prehistoric puppies weren’t certainly valued as hunters, she noted that “the ethnographic record shows that puppies in hunter-gatherer groups are often valued for their potential as future hunting partners.”
Along with the burials themselves, Perri found that the “importance of hunting dogs in this region is also demonstrated by the numerous dog-shaped clay figures (dogu), including a set that features a dog barking at three wild boar.” Or, “One Yayoi representation of dogs is found on a ceremonial bronze bell (dotaku) depicting a number of scenes, one of which is a boar surrounded by a hunter and a pack of dogs.” As shown here:
A 2500-year-old bronze bell depicting a Jōmon hunt with dogs. Image courtesy of Tokyo National Museum (http://www.tnm.jp/)
Perri concludes that while dogs were an integral part of the ancestral forest hunting culture, once an agricultural subsistence culture took over, the dog burials stopped as well.
As Grimm noted in his article and quotting Melinda Zeder, an archaeozoologist at the Smithsonian Institution National Museum of Natural History, “it may be a disparity in loyalty. “Humans were a bit of a fair-weather friend—we were not as reliable as they were,” she laughs. “We could do to be a little more doglike.” We couldn’t agree with that sentiment more.
Good Dog: Studies & Research
The influence of each species’ feeding ecology
Humans tend to be risk-averse, which is often illustrated by our decision when offered either $100 or the opportunity for a 50-50 shot at receiving either $200 or nothing. In general, humans go for the sure thing. We are not, as a species, risk-prone, or we would gamble on the shot at getting the bigger payoff.
It turns out that a number of studies across a broad range of species have shown that how a species responds to risk is predictable based on their feeding ecology. Animals who depend on erratic, ephemeral food sources, such as meat that they hunt or fruits that are patchy and only ripe for a brief time, tend to be risk-prone. They are willing to gamble on the big payoff. Species that eat diverse types of food or food that is more reliably available, such as vegetation, are risk-averse.
Some of our primate relatives are like us, and some are the opposite. For example, bonobos and lemurs (who both eat a very diverse diet that is mainly vegetarian) are risk-averse like us, choosing a sure thing of lower value over a chance at something better. Chimpanzees and capuchin monkeys—both meat and patchy fruit eaters—are different, being risk-prone and choosing the option that may yield a big reward but could leave then empty-handed. This pattern has appeared in closely-related species birds, too, where those who eat insects are risk-prone, while species who eat seeds are risk-averse.
Scientists haven’t fully explored how widespread this pattern of feeding ecology predicting risk-taking behavior is, but wolves and dogs are an interesting test case. These two species diverged quite recently in an evolutionary sense, but their feeding ecologies differ greatly. Wolves are primarily hunters and dogs are mainly scavengers. Hunting has a high failure rate, but the rewards of a big kill are enormous. In contrast, the source of food for the vast majority of dogs worldwide is human refuse, which tends to be available far more regularly.
In a recent study called “Exploring Differences in Dogs’ and Wolves’ Preference for Risk in a Foraging Task” scientists investigated whether wolves and dogs conform to the pattern seen across so many other species. Based on their different feeding ecologies, they predicted that compared with each other, wolves would be risk-prone and dogs would be risk-averse. The study was done at Wolf Science Centre in Austria, using dogs and wolves who were raised and live at the facility and have had the same overall experiences there.
The subjects of the study were trained to choose either a bowl that contained a dry pellet of food or a bowl that had a fifty percent chance of containing a piece of meat and a fifty percent chance of holding a stone. After each choice, the subject was given the contents of the bowl. All the wolves and dogs in the study were subject to tests to confirm that they understood the choice they were making and also to confirm that they preferred the meat to the dry food pellet.
The researchers found that the pattern of risk-taking seen in other species also applied to wolves and dogs. As expected, wolves were more risk-prone than dogs. However, there is more to this study than that simple conclusion. Wolves learned the system faster than the dogs, and the researchers acknowledge that they may have understood it better than the dogs. Additionally, dogs’ preference for the meat versus dry food pellet was not as strong as it was for wolves. Therefore, the risk of losing out and getting nothing for the chance to get something only a little better than a food pellet may not have been worth it to dogs. There was greater variation among individual dogs in risk-taking strategy compared with wolves, who were more similar in their choices, so it’s possible that there are dogs who are risk-prone as well as dogs who are risk-averse. (Dogs made the risky choice from 38 to 76 percent of the time, while wolves took the risky option 70 to 95 percent of the time.)
Overall, despite the conclusions made from the data in this study, direct comparisons of the choices made by these two species may require further study. It would be very interesting to learn more about decisions to take risks by dogs and wolves in a study with more than seven of each species, though I realize possible subjects for a study such as this are limited. It would also be fascinating to know about the decisions foxes and coyotes would make if presented with the same choices. Comparative research that include dogs as one species among many allow us to learn a great deal about how their evolutionary history and ecology have affected their behavior. It’s one of many ways that we can deepen our understanding of the animals who share our homes and live in our hearts.
Are We Smart Enough to Know How Smart Animals Are?
In Are We Smart Enough to Know How Smart Animals Are? Frans de Waal presents a fascinating history of the study of animal behavior and cognition. De Waal, who says his love of animals dates to his childhood, is a worldrenowned primatologist and ethologist and director of the Living Links Center at the Yerkes National Primate Research Center. We asked him to shift gears and give us his take on the canine mind.
Bark: Konrad Lorenz (co-founder of your field) wrote Man Meets Dog in 1954. And while it is still one of the best, if slightly flawed, books on canine behavior, why did it take so long for ethologists, and other researchers, to to study dog behavior?
Frans de Waal: Dogs were (and are) considered imperfect subjects of study because they are “unnatural.” Many ethologists, including Lorenz, feel that natural behavior under naturalistic conditions is what we should focus on, and the dog is a product of artificial breeding. Lorenz liked all animals, however, and so couldn’t resist describing his dog stories, and we should all be grateful.
Clearly, the dog is a mammal with many typical mammalian tendencies, so now scientists are finally seeing that the fact that they are domesticated also has advantages. For example, they are eager to work with us, they are generally not dangerous, they are smart, they have empathy. Lots of great things can be done with them. And they are easier to work with than other large mammals, such as apes and dolphins.
Bk: Can you give an example of how other species, including dogs, demonstrate empathy?
FdW: American psychologist Carolyn Zahn-Waxler sought to determine at what age children begin to comfort family members who sobbed or cried “ouch.” It turns out that children do so at one year of age. In the same study, Zahn-Waxler accidentally discovered that household dogs react similarly. Appearing as upset as the children by the distress-faking family members, the dogs hovered over them, putting their heads in their laps with what looked like great concern. This work has recently been repeated in different studies, more focused on the dogs themselves, and it is clear that these animals show empathic concern for humans.
The ancestor of the dog, the wolf, probably behaves the same. If “man is wolf to man,” as Thomas Hobbes liked to say, we should take this in the best possible way, including a tendency to comfort the whimpering and help the needy. This insight, of course, would undermine much of political philosophy based on Hobbes’ dog-eat-dog view of nature.
Bk: Do you think human bias has played a part in some of the canine cognitive studies?
FdW: At first, dogs were rated as more intelligent than even apes and wolves because they followed the direction of human pointing (at a bucket with food), whereas apes and wolves ignored human directions. Then it was found that wolves raised in a human home will act more like dogs, following human pointing, suggesting that the earlier failures with wolves were probably due to lack of bonding and attention. The same probably applies to the apes. Now, dogs are seen not just as smart but rather, as finely in tune with the species that bred them.
They have a special bond with us, as also reflected in the oxytocin studies, which show that human-dog contact increases this “cuddle” hormone in both. The dog is perhaps the only animal that performs at its peak when tested by humans, whereas many other animals are not so into us, hence need to be tested in different ways. This is yet more proof that cognitive testing of animals always needs to take into account what kind of animal we are dealing with: we need to find the most species-appropriate way.
Bk: In contrast to behaviorism’s reward/ punishment model, ethology views animals as “seeking, wanting and striving.” Why do you feel the latter is a more productive way to look at animals?
FdW: The behaviorists (followers of B. F. Skinner) totally overlooked natural animal tendencies. Trying to explain all behavior on the basis of reward and punishment, they could not explain why you can train a dog to fetch, but not a rabbit or a goat.
Predators are obsessed with small moving objects, which we see every day in our dogs as well as cats. Their interest sets up a learning situation where they are going to absorb many lessons about how to catch these moving objects, how to trick them, how to outsmart them. Dogs eagerly learn all of those things.
Reward and punishment are only small parts of the story; their natural hunting instinct is, in fact, the driver of the process. This is where behaviorism failed. It had some good ideas, many of them applicable to animal training, but its perspective was far too narrow as it lacked attention to natural tendencies and the evolution of behavior.
Bk: Why do you think Darwin used dogs to illustrate emotional continuity?
FdW: Darwin was a dog lover, and he knew that to get his message across about the continuity between human and animal emotions, the dog would be the easiest way to communicate. Darwin mostly worked on the expression of emotions (it’s hard to know what animals feel, but we can at least document how they signal various states, such as fear, submission, anger, affection). Of course, the dog is very expressive with its postures, facial expressions, tail-wagging, growling and so on. Darwin knew that most people could relate to all of this, and would have more trouble if he described other species that people have less exposure to.
Bk: In terms of an evolutionary advantage, how important is it for a species to have self-awareness, or theory of mind?
FdW: These capacities require large brains. In terms of recognizing oneself in the mirror or understanding what others know, the champion species are apes, dolphins, elephants and perhaps also the corvids (crow family). This doesn’t mean that dogs lack them. They probably have similar understanding, but not as fully expressed.
The more complex the societies of a species, the more demands there are on cognition, and perhaps canines do not need social understanding at the level of an ape or dolphin. I feel we need to judge animals on what they are good at and what they need to know to survive. In this regard, canines have lots of specialized skills, often related to their sense of smell, their pursuit of prey, their need for tight cooperation and so on. This is where we should test them out, and probably find remarkable skills.
Bk: Clearly, emotions are important to the understanding of behavior; how do they relate to and inform one another?
FdW: In my book, I left emotions out on purpose because I felt it would muddle things. But there can be no studies of cognition without attention to the emotions, and vice versa. The two go hand in hand. In our famous capuchin monkey experiment with the grape and the cucumber, for example, you can see not only that the monkeys judge what they get relative to what others get, but also their strong emotional response. You cannot study the one and ignore the other.
Good Dog: Studies & Research
What you say and how you say it both matter
Humans use both words and the intonation of speech to decipher the meaning of language, and it turns out that our dogs do, too. In a research paper called “Neural mechanisms for lexical processing in dogs” scientists investigated how dogs process the meaning of language. They found that dogs’ brains have even more in common with humans’ brains than previously thought. (It’s not clear when we will collectively stop being surprised by this, but I hope we always remain excited about new evidence to explain why we feel that dogs are kindred spirits.)
In this study, dogs who have been trained to remain still while their brain activity is recorded listened to recordings of their trainers talking. There were four types of recordings: 1) words of praise spoken with intonation typically associated with praise, 2) words of praise spoken with a neutral intonation, 3) neutral words spoken with intonation typically associated with praise, and 4) neutral words spoken with a neutral intonation.
Researchers analyzed the brain activity of the dogs in response to each of the recordings, and came to several conclusions about the way that dogs respond to words and the intonation of human speech. The dogs processed the vocabulary in the left hemisphere of their brains, which is where humans also process the meaning of words. The dogs processed the intonation of the words separately, in a different region of the brain. Just as humans do, dogs processed the intonation of human speech in the right hemisphere of their brain. Dogs also process sounds that convey emotion without words in this same region of the brain’s right hemisphere.
Dogs process both words and the intonation of human speech to decipher meaning. Just as humans do, they process these two aspects of speech separately, then integrate them to determine the full meaning of what was said. Only the praise that was spoken like praise—higher pitched than normal speech and with more variation in pitch—activated the reward centers of dogs’ brains. Though they may understand words of praise said in any manner, it only makes dogs happy to hear us praise them when we do it with proper feeling.
This research does more than reveal yet another similarity in the way that human and dog brains process information. It also suggests that the ability to connect a word to a meaning did not develop with the evolution of spoken language. Rather, it is a more ancient ability that can be made use of in the context of the human-dog relationship to link specific sounds to specific meanings.
The take away messages from this research are that dogs process two parts of spoken language—words and intonation—the same way that humans do and if you want to make your dogs happy, you have to praise them like you mean it!
Good Dog: Studies & Research
Beliefs do not substitute for data
Watching dogs play is very exciting, and there has been a lot empirical research on how and why dogs (and other animals) engage in this activity with boundless zeal. A number of people have asked me to comment about dog play after reading this section in a new book by Raymond Coppinger and Mark Feinstein called How Dogs Work. So, I decided to do so.
The authors begin their chapter 9 on play by claiming, “Hundreds of scientific papers have been written on the subject of ‘play’ behavior—an activity for which dogs are, of course, famous.” Recognizing that there is a solid and growing literature on play—there’s really no reason to put the word play in square quotes—I assumed that what followed would be a detailed review of this research, but rather, what I discovered was a disjointed discussion of play and not an in-depth review of the scientific literature. Instead, the authors offer their own unpublished observations and the results of unpublished student projects, all of which are impossible to assess.
Do dogs and other animals actually play? Coppinger and Feinstein write that they put the word play in scare quotes because “in spite of the fact that people feel like they know it when they see it, it’s not at all obvious that play is a unitary ‘thing-in-itself’ that can easily be characterized, let alone explained in evolutionary terms.” No one I know who has spent years studying play would argue that play is a “unitary ‘thing-in-itself’,” nor would they agree that play cannot be explained “in evolutionary terms.” Indeed, some of the references the authors include show there are a number of highly plausible evolutionary explanations (and the University of Tennessee’s Gordon Burghardt, who has studied comparative aspects of play for many years and wrote The Genesis of Animal Play, provided the Foreword for Coppinger and Feinstein’s book).
Why do animals play? Briefly, various theories have been offered about why animals play, and there’s no one explanation that fits all examples of animal play. Detailed comparative data show play is important in social development, physical development, and cognitive development. And, neurobiological research strongly suggests play can be pleasurable and fun and animals may simply play because it feels good, “for the hell of it.” Indeed, many researchers are taking fun seriously, and the 25th anniversary issue of the journal Current Biology was devoted to the biology of fun with many play researchers weighing in on the topic. Coppinger and Feinstein write, “We agree that there is good reason to believe that animals derive pleasure from play - indeed they do from all of their motor activities.” (my emphasis) While animals might derive pleasure from play, eating, and sex, it’s difficult to argue they feel good running from competitors or predators, but the necessary research has not been done.
Based on an extensive review of available literature, my colleagues Marek Spinka, Ruth Newberry, and I proposed that that play functions as training for the unexpected by increasing the versatility of movements and the ability to recover from sudden shocks, such as the loss of balance and falling over, and to enhance the ability of animals to cope emotionally with unexpected stressful situations. To obtain this training, we suggested that animals actively seek and create unexpected situations in play and actively put themselves into disadvantageous positions and situations.
Comparative data from a wide range of species support this hypothesis. And, while it is difficult to test these ideas in the field, a study of mountain goat kids by Rachel Théoret-Gosselin, Sandra Hamel, and Steeve D. Côté called “The role of maternal behavior and offspring development in the survival of mountain goat kids“ showed that “play behaviors could enhance the emotional resilience to stress not only for unpredicted events but also in stressful group situations because play could reduce aggressiveness in gregarious species.” More field data are needed and this study is an excellent example of what needs to be done.
The play bow: Are dogs really confused when they play and what does this mean?
The authors also dismiss the detailed work that has been conducted on the play bow, a highly ritualized and stereotyped action by which animals signal their intention to play (please see accompanying image). When dogs and other animals bow they crouch on their forelimbs, raise their hind end, and occasionally wag their tail and bark. Coppinger and Feinstein write, “But we wonder if the so-called play bow in fact really has any adaptive, let alone cognitive, significance.” A good deal of very detailed research has been conducted on the bow by my research group and also by Barbara Smuts and her students that clearly supports the claim that bows are adaptive and have cognitive significance (please also see along with Mechtild Käufer’s excellent book called Canine Play Behavior: The Science of Dogs at Play and a comprehensive review essay by Elisabetta Palagi and eight other play experts called “Rough-and-tumble play as a window on animal communication“). The abstract for this excellent evidence-based and extremely significant up-to-date essay reads: Rough-and-tumble play (RT) is a widespread phenomenon in mammals. Since it involves competition, whereby one animal attempts to gain advantage over another, RT runs the risk of escalation to serious fighting. Competition is typically curtailed by some degree of cooperation and different signals help negotiate potential mishaps during RT. This review provides a framework for such signals, showing that they range along two dimensions: one from signals borrowed from other functional contexts to those that are unique to play, and the other from purely emotional expressions to highly cognitive (intentional) constructions. Some animal taxa have exaggerated the emotional and cognitive interplay aspects of play signals, yielding admixtures of communication that have led to complex forms of RT. This complexity has been further exaggerated in some lineages by the development of specific novel gestures that can be used to negotiate playful mood and entice reluctant partners. Play-derived gestures may provide new mechanisms by which more sophisticated communication forms can evolve. Therefore, RT and playful communication provide a window into the study of social cognition, emotional regulation and the evolution of communication systems.
The so-called play bow. Based on an unpublished student project in which “Border collies were confronted with normal and drugged roosters”, Coppinger and Feinstein believe that the “so-called play bow” is a posture assumed by an animal confused by its next move. They write, “... the play bow occurs when an animal is in a temporarily indeterminate state ... In short, the ‘playing’ animal is in conflict about its next move - and the play bow in fact looks just like a combination of multiple conflicting behavioral shapes.” The authors ignore detailed research that shows how play bows are extremely stereotyped (they are what ethologists call a modal action pattern), they vary in shape and duration depending on where they are performed in a play bout, and they allow a dog to perform a wide variety of movements from this posture. There are no data that support their belief and the student’s data are impossible to assess. And, it’s not clear at all why they refer to the “so-called play bow,” when many researchers have studied it and concluded, based on substantial data, that it is indeed used almost exclusively in the context of play both as a play invitation signal and also to maintain the play mood.
Let’s briefly think about what it means when a dog or other animal is confused, because every definition I can find indicates that there have to be cognitive and emotional underpinnings. In the case of dog-dog play, a simple view would be that Harry (a dog) wants to play with Mary (another dog) and that Harry isn’t sure what to do so he carefully pays attention to what Mary has done and is doing, and tries to factor this information into what she is likely to do in the future. In essence, Harry is pondering if he chooses to do “X” or “Y,” what will Mary do (and, of course, vice versa). Because play is indeed a hodge-podge of various actions, a kaleidoscopic behavior, on the authors’ view, Harry is confused, and to overcome his confusion he performs play bows.
There are no data that support the belief that dogs are confused when they play, however, there are data that show that there is a good deal of rapid of thinking and feeling on-the-run based on what Harry thinks and feels Mary is likely to do during the on-going interaction (and vice versa). These sorts of interactions make it clear that play is also a good place to observe and to study what researchers call a “theory of mind,“ because Harry and Mary need to pay very close attention to what each has done and is doing, and how that will influence what she or he is likely to do in the future (for further discussion please see Alexandra Horowitz’s essay called “Attention to attention in domestic dog (Canis familiaris) dyadic play“). There is a good deal of mind-reading going on here as Harry and Mary make careful and rapid assessments and predictions of what their play partner is likely to do.
The cognitive and emotional underpinnings of “being confused” are rather rich, and do not lend themselves to simple mechanistic explanations that are favored by the authors. Available and ample data for a number of different species show there are predictable rules of play that cross species lines, namely, ask first, be honest, follow the rules, and admit you’re wrong. This is why play is so exciting to engage in and also so much fun to watch and to study. And, this is also why play among young and old dogs only rarely escalates into injurious aggression, although the authors recall an instance when play among four-week-old Border collie littermates was fatal and use this observation to claim that play “can itself cause significant harm” (p. 165). Indeed, Shyan, Fortune, and King (2003) reported that fewer than 0.5% of play fights in dogs developed into conflict, and only half of these were clearly aggressive encounters. Their data agree with our own observations on wild coyotes and free-running dogs at play.
Behavioral variability. Another example of a claim that is countered by available data centers on behavioral variability in young dogs and wolves. Coppinger and Feinstein write, “When we observe wolves, we see a similar picture. Wolf puppies are often noticeably more robust and varied in their play routines than dogs of the same size and age. This means, according to our hypothesis, that they should have more available motor patterns than the dogs do. That is in fact the case.“ (my emphasis) However, they offer no data.
Along these lines, years ago Robert Fagen, another play expert and author of the classic book Animal Play Behavior, analyzed the sequential variability of play and aggression in young dogs (beagles), wolves, and coyotes using data my students and I collected, and discovered that social play in the beagles was more variable than social play in wolves and coyotes of the same age (and coyote play was more variable than wolf play). These data were published in an essay I wrote with John Byers (“A critical reanalysis of the ontogeny of mammalian social and locomotor play: An ethological hornet’s nest,” in K. Immelmann, G. W. Barlow, L. Petrinovich, and M. Main, Eds., Behavioral Development, The Bielefeld Interdisciplinary Project. New York: Cambridge University Press, pp. 296-337, 1981) that the authors list in their reference section. And, we also found that young beagles and wolves shared the same basic ethogram and number of motor patterns. Perhaps working dogs such as Border collies are different from beagles and other dogs, but we really don’t know if this is the case.
The way in which the authors routinely dismiss a wealth of detailed research on animal play is characteristic of much of their book, that is essentially a tapestry of criticism using stories and unpublished projects in lieu of published data. It’s easy to see how one might walk away feeling that just about everyone else is wrong about dog behavior, cognition, emotions, and consciousness, and much of the research that has been done can be tossed into the garbage because it’s merely debris.
All in all, the one-sided assault on the ever-growing literature in the growing field called cognitive ethology (the study of animal minds) fails. How Dogs Work does not really tell us how dogs work, but rather provides an extremely narrow view of mainly working dogs as machines. I find the topic to be of great interest and am always eager to learn more about why some people favor reductionist and mechanistic accounts to explain the behavior of complex sentient beings (see, for example, Sara Shettleworth’s book, Fundamentals of Comparative Cognition). However, How Dogs Work doesn’t convince me that the authors’ over-arching views are tenable. Beliefs don’t substitute for data that have been reviewed by peers, and there are plenty of data that are readily available.
All in all, we really know far more than the authors offer, and for numerous wide-ranging and critical discussions of many different aspects of dog behavior I suggest Domestic Dog Cognition and Behavior: The Scientific Study of Canis familiaris edited by Alexandra Horowitz, Adam Miklosi’s Dog Behaviour, Evolution, and Cognition, The Social Dog: Behavior and Cognition edited by Juliane Kaminski and Sarah Marshall-Pescini, and Mechtild Käufer’s Canine Play Behavior: The Science of Dogs at Play. For more on play I highly recommend the excellent and comprehensive review article by Elisabetta Palagi and her colleagues called “Rough-and-tumble play as a window on animal communication“ and (in addition to the references above) Sergio Pellis and Vivien Pellis’ The Playful Brain: Venturing to the Limits of Neuroscience.
What’s so incredibly exciting about the study of play behavior and the cognitive and emotional lives of dogs and other animals is how much we’re learning about how individuals negotiate challenging and complex social and non-social situations by carefully analyzing what’s happening and by using hard-wired actions when needed (for example, when they need to do the right thing instantaneously or the first time they are faced with a specific situation and there’s no room for error), along with behavior patterns that require careful thought and flexibility motivated by what individuals are feeling about the situation in which they find themselves.
Please stay tuned for more on dog behavior, cognition, and emotions, because there is a lot of research being done by research groups around the world, and we still have a lot to learn. Dogs are amazing sentient beings who challenge us in many different ways.
I thank a number of people for help with this essay.
Note: In a number of email messages I've been asked if I knew what happened to the 1000’s of sled dogs dogs for whom Dr. Coppinger was responsible. On page 25 we’re told, “Some four thousand dogs ‘went through the yard’” when “Ray spent fifteen years breeding and training dogs that pull sleds.” I have no idea what happened to these dogs, but according to some people I consulted, this is an incredibly large number of dogs, an average of around 267 a year.
Wellness: Healthy Living
Toxic chemicals also found in dog food
A long-term study conducted in Britain has found that male dogs are losing fertility, and that exposure to environmental chemicals (ECs) that have leached into the environment may be to blame.
The dogs—Labradors, Border Collies, German Shepherds and Golden Retrievers bred to aid the disabled—made an ideal group to explore the larger question of a decline in human semen quality that has been occurring since long before this study.
This twenty-six year long study, 1998-2014, was conducted by Richard Lea and colleagues at Nottingham University’s school of veterinary medicine. They collected annual samples of semen from dozens of dogs, all from the same breeding program, all healthy and well cared for. Each year, the same problem recurred; a 2.4 percent dip in sperm motility, that is the ability to swim in a straight line. In addition to monitoring semen quality, they analyzed health records, finding an increase in cryptorchidism, a condition in which the testicles fail to extend normally to the scrotum. Over the same years, fewer male pups were born than females, also there was an increase in fetal and prenatal female mortality.
And, lurking in the samples of semen and testicles of dogs obtained from neutering, it found ECs—chemicals that tamper with hormones. The chemicals include polychlorinated bisphenol (PCB), a compound banned in 1977, and diethylhexyl phthalate (DEHP). PCBs don’t readily break down while phthalates are common in a wide number of products, from cosmetics to detergent. Both chemicals are associated with fertility issues and birth defects.
In human babies, exposure to chemicals has been linked to faulty development of semen quality and cryptorchidism. According to the study, such reproductive problems often cluster in geographical areas, and so are suspected of having a common cause; exposure to hormone-disrupting chemicals is “thought to be the initiator.” To explore the same possibility in dogs, chemicals were measured in canine testes and semen taken from the same geographical area where the study took place.
Both chemicals “perturbed sperm viability, motility and DNA integrity in vitro.” The researchers concluded that the direct effects of chemicals on sperm “may contribute to the decline in canine semen quality” that parallels that in humans.
“Why the dog?” said Dr. Lea. “Apart from the fact that it is a great population of animals to work with, dogs live in our homes, they sometimes eat the same food, they are exposed to the same environmental contaminants that we are, so the underlying hypothesis is that the dog is really a type of sentinel for human exposure.”
The same ECs were found in a range of commercially available dog foods. DEHP and PCB153, “were detected in adult dog testes and commercial dog foods at concentrations reported to perturb reproductive function in other species.”
While the brands were not named, they are reported to be both wet and dry forms sold worldwide. The scientists don’t know how the chemicals made it into the food, but since they are not deliberate additives, they may have leached from the packaging or processing sources.
These overall findings are troubling, but they also noted that: “Amongst the dry dog food samples, one sample designed for puppies (1 to 24 months of age) had higher concentrations … relative to the other samples tested.”
Plus, while the researchers cannot say the dog food is a direct source of the ECs, the New York Times reports that "Dr. Lea said it was probably a major one."
What is known is that the chemicals wound up in dog’s testicles, where they messed with sperm motility and viability. “This may be a way by which environmental chemicals directly affect male fertility.”
While the dogs in the study were still able to reproduce, it’s hardly reassuring that, once more, the dogs who share our homes also share our diseases, unwittingly, acting as the “canary in the mine” for us.
Good Dog: Studies & Research
Studies on dogs following gestures.
AT TWO WEDDINGS, darling ring bearers paraded down the aisle proudly holding the prized objects. They couldn’t have been more than six. When they suddenly stopped—as six-year-olds tend to do—to look at something on the ground, guests leaned into the aisle and pointed toward the beaming faces ahead. Smiles filled the crowd as they continued on their way.
At one wedding, the ring bearer was a little boy, and at the other, a dog.
If we’ve spent any time with companion dogs, we aren’t surprised when a dog stops to check out the ground. It also shouldn’t surprise us that a dog might go where we point. Pointing is about social communication, and it often feels like dogs are right there with us, sometimes even more than members of our own species.
In the last 20 years, dogs’ attention to our communicative gestures—particularly this thing we do with our arm and finger—has attracted enormous attention from researchers around the globe. In fact, the pointing gesture is so fundamental that seemingly no article on the canine mind is complete without a sentence such as “dogs read our gestures, like pointing, more flexibly than any other animal” (New York Times), or—more boldly in Time—“While chimps and even wolves lack an innate ability to understand what pointing means, dogs come by the knowledge naturally.”
These statements tend to produce any number of reactions in dog owners, from “Obviously,” sometimes accompanied with a side of, “Why do they bother to do this research anyway?” to the flip side: “My dog doesn’t do that … what are they talking about?” Or even the more nihilistic view: “Sure they do, but who cares?”
Here’s why we care: this one little gesture, in all its complexity, could be a core feature of the intimate bond we share with dogs.
Since the late 1990s, researchers have tried to uncover why and how dogs pick up on our cues. Initially, key questions focused on whether their ability to follow the pointing gesture arose from our long-standing co-evolutionary history or, alternatively, if they learned the behavior over the course of their individual lives.
Pointing Is About Us
Pointing is something we humans do as part of our social communication, and it is useful only because we all agree on how it should be interpreted. Imagine if your point were perceived as, “Hey! Check out my fingertip. No dirt under my nail. Wonderful, huh?” Not exactly useful for communication. Fortunately, we understand that pointing creates a shared experience beyond our fingertips; pointing draws someone’s attention past our outstretched index finger to something out there in the world.
This cooperative gesture serves us well. Yelling, “Look out!” is only somewhat informative, but yelling, “Look out!” and pointing can help a fellow human locate and respond to a Frisbee sailing in at head level or Godzilla rampaging down Fifth Avenue. Communication achieved.
Despite our mothers’ reminders that pointing is rude, it has a function: it reflects our ability to hold shared attention with others, which could also indicate that someone else is aware of the same thing that we are. Pretty meta. Joint attention can thus be associated with an ability to infer others’ mental states, which is considered an important social capability in humans.
At about six months, children start following the gaze and gestures of others. We start pointing around our first birthday and become increasingly point-savvy as we age. When toddlers see something of interest and point at it, they become excited when we also look. They will also point when seeking something or to provide information (I want that. You dropped something). Regardless of how it’s used or understood at any given age or moment, pointing intrinsically aids our communication with one another.
Do Dogs Get the Point?
It shouldn’t come as a surprise that much of the academic interest in the canine mind that blossomed in the late 1990s was actually largely about us, investigating to what extent dogs responded to our communicative gestures— notably, our pointing. In research labs around the world, it has been a pointing party ever since.
Watch any program covering research into the canine mind and you’re bound to hear mention of studies involving a dog, two cups and a pointing human. The experiment, commonly referred to as the object-choice task, follows some variation of this procedure: a dog first learns he can get a treat for approaching either of two identical cups. He then watches as a person points to one of the cups. Will the dog follow the point to the cup?
Human children are quite good at this task, and numerous studies confirm that dogs are, too. From an early age, dogs are highly responsive to this gesture. Dogs do well when a person points with a foot, or bows or nods. They’ll also respond to what’s commonly referred to as a “momentary” point, in which the person points and then lowers his or her arm before the dog makes a choice. They will follow the point even when a person stands by one cup and points at the other. Although we all know smell is a major player in the canine world, it doesn’t appear to factor greatly into dog performance; when food is hidden under one cup and nobody points, they don’t do so well. Some researchers describe their performance as “remarkable” and “outstandingly flexible.”
Not all species catch our communicative drift. A bee that flies into your car will never be aided by your outstretched arm pointing toward the open window. Given dogs’ long history with us, researchers wondered whether canine sensitivity arose through the domestication process—in which case, wolves, their closest relative, might be less adept in this task—or, on the other hand, whether it’s a product of learning and dogs’ individual life experiences. Or maybe the reality is not so black-and- white. What underlies their highly flexible ability?
Wolves do not follow our gestures as flexibly as dogs. Nor do chimpanzees, our closest relatives. This isn’t to say that wolves (or chimpanzees) can’t or don’t do it. Extensively socialized wolves and enculturated chimps—those highly familiarized with human behavior— can follow our points, but dogs generally respond more readily and easily, and wolves need more exposure to perform similarly. In 2002, Brian Hare of the Duke Canine Cognition Center pulled together then-current research on dogs, wolves and chimpanzees and, in an article in Science, concluded, “Dogs’ social-communicative skills with humans were acquired during the process of domestication.”
Both Nature & Nurture Point to Success
More immediate genetic influences, like artificial selection, could also influence dogs’ skills. Márta Gácsi and colleagues at the Family Dog Project in Budapest found that while all dogs tested followed the point better than chance would predict, dogs bred for cooperative work (like gun dogs) performed better than those bred for independent work (like guard dogs). All the dogs in the study were living as pets and none had received special training, implying that genetics plays a role at some level in enhancing dogs’ ability to follow our gestures.
At the same time, individual life experiences could also contribute to a dog’s responsiveness. For example, the reactions of shelter dogs to our pointing gestures vary widely, and a small group of intensively socialized lab-raised dogs did not fare well in the task.
Lucia Lazarowski of the Comparative Cognition Laboratory at Auburn University, one of the investigators in the lab-raised dog study, saw their challenges first-hand. But when she later adopted Captain, a study participant, and informally examined his responsiveness to pointing, she found he performed much better in her home: “He actually looked in the direction I pointed and sniffed in the area I was pointing to. During the test, however, he was one of the more non-responsive dogs. Now, we like to play a game where I toss small treats around the room for him to hunt, and if he can’t find them, sometimes I’ll point to them, so he probably has picked it up from that.” Captain’s transition to canine pointfollower highlights that learning and life experiences can factor into the skill.
The person behind the point can also affect dog performance. Amy Cook, CDBC, CPDT-KA, conducted a study on the topic at the University of California, Berkeley; reporting in Animal Cognition, Cook noted that when owners and strangers were pitted against one another (in what I hope was described as a “point-off”), dogs tended to follow their owners, even when they received no reward (i.e., the point did not lead to the dog getting food). As Cook explains, “Dogs make decisions by attending preferentially to social signals from humans with whom they have become more familiar.” Many of us think it’s all about us, and our dogs might agree.
If dogs respond to the pointing gesture based on whose finger is doing the work, then again, it looks like life experiences could be controlling the switches. But not so fast: Cook suggests that this unique spin on the issue— dogs being more attentive to a familiar person—could have been shaped by evolutionary pressures to bond with a caretaker. Attachment relationships between dogs and their humans are well documented and, as Cook says, going with your person could be “a successful strategy in the long term.”
Isn’t it nice when everyone can be right? Dog responsiveness to our communicative gestures could be a product of their evolutionary history plus their ability to learn rapidly once in a human environment. In a 2009 article in Behavioural Processes, Pamela Reid, CAAB and vice president of the ASPCA’s Anti-Cruelty Behavior Team, reflects on what’s behind canine responsiveness to our social cues: “Dogs are too skilled for it to be pure trial-and- error learning. Yet it is improbable that a versatile behavior like this would be largely innate.” She suggests that what we see in dogs is an adaptive specialization of learning. “In essence, they come with a built-in head start to learn the significance of people’s gestures, in much the same way that white-crowned sparrows acquire their species-typical song and ducklings imprint on their own kind.” This fits in well with what is understood of instinctual or innate behaviors. As Jack Hailman explained in his inf luential piece in Scientific American in 1969, “How an Instinct Is Learned,” species-specific behaviors require some amount of experience and development.
When Patricia McConnell, CAAB, mulled over the pointing research on her blog, “The Other End of the Leash,” she agreed that dogs could be “predisposed to learn to follow a pointing gesture.” McConnell also highlights something you might have seen yourself: present a very young puppy with an outstretched finger and that puppy is going to approach your fingertip, not follow it to a distant location. McConnell’s point is that point-following in puppies is not automatic, although they learn it very easily.
To this, Reid adds, “Just because a skill appears early in development does not preclude learning. It does, however, demand that puppies be highly attentive to the actions of humans, a tendency that has been confirmed in studies of dog-human attachment.”
What Do You Understand, Dog?
What do dogs think of all this? What does it mean to be a dog who “understands” our pointing gesture?
A 2013 article by Ádám Miklósi and József Topál of the Family Dog Project in Trends in Cognitive Sciences concludes by highlighting that “dog social competence [appears] sometimes ‘infant-like’ or ‘human-like,’ but, importantly, the underlying mental mechanisms may turn out to be quite different.”
It’s hard enough for us to figure out if, for example, our boss is merely suggesting that we do something or telling us to do it. The same is true for dogs and the pointing gesture. Do dogs see pointing as an imperative—“You. Go there.”—or as simply providing information or a helpful suggestion—“I recommend that you go there.”—a subtle yet meaningful difference. A 2011 article published in Applied Animal Behaviour Science by Helene Pettersson and colleagues found that, like children, dogs are more likely to follow a point when it is accompanied by a cooperative tone of voice as opposed to a prohibitive tone. At the same time, dogs sometimes follow the point to an empty container, leading some to wonder whether, under certain circumstances, dogs might perceive the gesture as a command.
Like humans, dogs seem to distinguish when communication is—or is not—intended for them, although they could be relying on a more limited set of cues. Numerous studies find that initiating eye contact and using high-pitched vocalizations help dogs understand that the communication is for them. Setting is also important. In a 2011 study reported in PLoS ONE, Linda Scheider and colleagues found that if a person points to a location where a dog has never experienced reinforcement, the dog is not as likely to follow as he would be if he had previously received reinforcement there (making me wonder whether the ring-bearer dog would spontaneously follow the point to the altar).
At some level, every pointing gesture suffers from a fundamental ambiguity: we might be pointing to a particular object, or we might be pointing to a specific space that happens to be inhabited by a particular object. Usually, we can figure it out without too much cognitive difficulty. Even nine-monthold infants understand when pointing refers to an object as opposed to the place where the object is located.
How about dogs? In a study recently published in the Journal of Comparative Psychology by Tibor Tauzin and colleagues, an experimenter pointed at one of two different toys on either side of him. Before the dog could approach, the experimenter switched the location of the objects in full view of the dog. The researchers wondered whether the dog would approach the object that had initially been pointed at but that was now in a new location, or to the original location of the point. The result? Dogs did not follow the object to its new location. Instead, they approached the old location, which seems to imply that, for the dog, pointing could be more about the location than the pointed-at object.
For those of us who live or work with dogs, much of the value of pointing studies lies in what we do with the results. Despite being unflashy, the pointing gesture is actually rich in dimensions and angles that we can explore with our dogs. As Reid recommends, “Take note of your body gestures. Does your dog attend to your gestures in all cases, or only in certain contexts? Dogs are often way more sensitive than we can grasp. They’re not trying to fool you or trick you, get one over on you or cheat the system. Attending to our gestures is just what dogs do. It’s who they are.”
Cook, A., et al. 2014. My owner right or wrong: the effect of familiarity on the domestic dog’s behavior in a food-choice task. Animal Cognition 17: 461–470.
Franco, F., and G. Butterworth. 1996. Pointing and social awareness: declaring and requesting in the second year. Journal of Child Language 12(2): 307–336.
Gácsi, M., et al. 2009. Effect of selection for cooperation and attention in dogs. Behavioral and Brain Functions 5:31.
Hailman, J.P. 1969. How an Instinct Is Learned. Scientific American 221(6): 98–106.
Hare, B., et al. 2002. The domestication of social cognition in dogs. Science 298(5598): 1634–1636.
Hochman, D. 2014. You’ll Go Far, My Pet. New York Times, April 11.
Kaminski, J., et al. 2011. How dogs know when communication is intended for them. Developmental Science 15: 222–232.
——— and J. Nitzschner. 2013. Do dogs get the point? A review of dog-human communication ability. Learning and Motivation 44(4): 294–302.
Lazarowski, L., and D.C. Dorman. 2015. A comparison of pet and purpose-bred research dog (Canis familiaris) performance on human-guided object-choice tasks. Behavioural Processes 110: 60–67.
Miklósi, A., and J. Topál. 2013. What does it take to become ‘best friends’? Evolutionary changes in canine social competence. Trends in Cognitive Sciences 17(6): 287–294.
Pettersson, H., et al. 2011. Understanding of human communicative motives in domestic dogs. Applied Animal Behaviour Science 133(3-4): 235–245.
Reid, P. 2009. Adapting to the human world: Dog’s responsiveness to our social cues. Behavioural Processes 80(3): 325–333.
Scaife, M., and J.S. Bruner. 1975. The capacity for joint visual attention in the infant. Nature 253: 265–266.
Scheider, L., et al. 2011. Domestic dogs use contextual information and tone of voice when following a human pointing gesture. PLoS ONE 6(7): e21676.
———, et al. 2013. Do domestic dogs interpret pointing as a command? Animal Cognition 16: 361–372.
Tauzin, T., et al. 2015. What or where? The meaning of referential human pointing for dogs (Canis familiaris). Journal of Comparative Psychology 129(4): 334–348.
Udell, M., et al. 2008. Wolves outperform dogs in following human social cues. Animal Behaviour 76: 1767–1773.
Zimmer, C. 2009. The Secrets Inside Your Dog’s Mind. Time, September 21.
Good Dog: Behavior & Training
Differential use of the left and right nostril
The common wisdom that dogs can smell fear doesn’t give dogs full credit to the nuances of their ability to sense emotion through their noses. A recent study titled “The dog nose “KNOWS” fear: Asymmetric nostril use during sniffing at canine and human emotional stimuli” examined dogs’ tendencies to sniff various substances with the right or the left nostril. Exploring this side bias may seem like looking at random details, but the side of the nose used to sniff something tells us a lot about the dog’s emotional reaction to the odor. The use of one side of the body indicates a differential use of one side of the brain or the other, which is a clue to the dog’s emotions.
The left side of the brain processes more positive emotions such as happiness and excitement as well as stimuli that are familiar. The right side of the brain tends to take over when a dog is processing negative emotions such as sadness or fear as well as novel stimuli. In general, the right side of the body is controlled by the left hemisphere of the brain and vice versa. However, the nose is an exception; the right nostril sends information to the right side of the brain to be processed and the left nostril sends its information to the left side. The findings of this study suggest that the pathways used to process various olfactory stimuli are dependent on more than just whether they elicit negative or positive feelings.
Eight odors were tested—four from dogs and four from humans. The four human odors were collected as sweat from donors who were joyful, fearful, physically stressed, or in a neutral situation. The joyful and fearful states were elicited by movies, and the physical stress odor was collected after donors ran for 15-minutes. The four canine odors were collected from dogs who were happy following a play session with the guardian, stressed by isolation in an unfamiliar place, disturbed by a stranger approaching the car, and dogs who were asleep. The dogs who “donated” odors were different from the dogs whose sniffing behavior was studied.
To further explore the phenomenon of side bias in sniffing, the guardians of the dogs in the study filled out a questionnaire related to each dog’s temperament. During the study, dogs were led to a video camera under which was mounted a Q-tip saturated with various odors. The videos captured the dog’s sniffing behavior so that it was possible to determine a laterality index for each dog for every odor based on the amount of time spent sniffing with each nostril. A laterality index of 1.0 indicated exclusive use of the left nostril and negative 1.0 indicated exclusive use of the right nostril. Dogs’ cardiac activity was also recorded during the tests of each odor.
I’m sure it’s the science geek in me, but I got a kick out of reading the sentence, “Results for nostril use are shown in Figure 2.” Three of the odors elicited consistent sidedness in nostril use and five of them did not. Dogs more frequently used the right nostril to sniff the canine isolation odor. They more frequently used the left nostril to sniff the human fear odor and the odor from human physical stress.
There were two ways in which the results of the questionnaire were correlated with the laterality pattern for a particular odor. The higher a guardian ranked the dog’s fear/aggressiveness to other dogs, the more likely that dog was to use the right nostril for sniffing the disturbed canine odor. This suggests that individual differences in emotional arousal and perhaps even in temperament influence asymmetries in sniffing behavior. Dogs with higher scores for predatory behavior used the left nostril more for sniffing the odor that came from physically stressed humans. This makes sense when we consider that it is structures in the left side of dogs’ brains that are involved in predatory behavior.
Dogs’ brains are every bit as amazing as their noses, as research about both of them reveal!
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