Dissecting Behavior

Dogs, Science, and the Biology of Behavior

Tag: dogs

Bad Science: Quadrants of Operant Conditioning

People become dog trainers for various reasons. Often, these individuals will talk about a dog’s “performance,” yet this undoubtedly has a variety of interpretations. After all, what is performance? Is it speed? Strength? Accuracy? Reliability? Chat up a few trainers involved in any professional sport (canine or human) and you will see that there are numerous beliefs both for which methods produce the best results for the desired performance as well as for what reasons. Should our toes be pointing straight ahead or at an angle when doing a squat? Should we stretch before or after an activity? With dogs though, the question is even more convoluted because here the concerns are not just about performance: they are also about welfare.

Animal welfare is a vast topic and one that cannot be approached from A-Z in a single sitting. Many philosophers and scientists devote their entire lives to traversing the quagmires of non-human animal welfare issues and so I am not going to put all of my roulette chips down on 28 black and defend my choice in the never ending spin of the animal welfare debate wheel. In a perfect world, conversations are always productive. In the actual world, this is often a rare occurrence. But to the point, the conversation that might be the least productive in dog welfare is the assertion that techniques which use positive reinforcement and negative punishment are ethical; while techniques which use positive punishment and negative reinforcement are unethical. This issue is so emotionally charged and emblazoned in the industry that often the supporting evidence for a claim about the ethical nature of a technique revolves solely around the interpretation of what quadrant of operant conditioning the technique relies on.

Skinners-box1-277x300Common illustration of basic learning concepts in a 2×2 grid often called “the Quadrants.”
(note, while often attributed to B.F. Skinner, this is a false attribution)

For example, many trainers claim that a technique called Behavior Adjustment Training (BAT) is unethical because they see it as negative reinforcement. For those unfamiliar, BAT removes a stimulus (which a dog finds threatening) at a distance great enough for the dog to remain calm and not show signs of being overly agonistic (such as growling, snarling, barking, etc.) [note: typically it is the dog that is moving, not the scary stimulus].  Because you repeatedly remove something (in this case, the thing the dog doesn’t “like”) to reinforce calmer behavior, many trainers label this type of training as negative reinforcement—and because negative reinforcement is claimed to be unethical, BAT must therefore be unethical.  Problematically, BAT was designed to steer owners away from using harsh punishments and the method itself creates no signs of undue harm on the dog; so, if the interpretation of the quadrants of operant conditioning cause trainers to conclude that BAT is unethical, then there is a serious problem with the convention because calling BAT unethical is like calling Mr. Snuffleupagus from Sesame Street a serial rapist.

Since 1975, various scientists have pointed out that learning events can rarely, if ever, be labeled solely as positive or negative (e.g. Michael 1975, Baron & Galizio, 2005; Baron & Galizio, 2006; Tonneau, 2007). For example, imagine a rat in a black box at freezing temperature. They have a lever which activates a heater for a short period of time. As the rat stays in the box, an increase (reinforcement) in lever-pressing is noticed over time. Here is the paradox: does lever-pressing increase because of the addition (positive) of heat or the cessation (negative) of cold? The answer is yes.

[This example is paraphrased from an actual experiment conducted by Weiss & Laties published in Science in 1961]

In the physical universe, the addition of one stimulus is always met with the removal of another stimulus. Regardless of what type of matter (energy) this stimulus is, energy cannot be created or destroyed, and so within any closed system you have to remove something to add something and you have to add something to remove something. This is a fundamental property of the universe and is analogous to the idea that two opposing baseball teams cannot win the same game: in order for one team to win, another team has to simultaneously lose.  This prompts us to ask two questions: 1) are the quadrants of operant conditioning mutually exclusive?; and 2) if they are not mutually exclusive, then are we able to stipulate that they are not occurring at the same time during a learning event?

Most examples of what dog trainers consider positive reinforcement rely significantly on negative reinforcement elements (e.g. the removal of hunger). Food is great, but as a motivator we are removing hunger (negative reinforcement), however it is also positive reinforcement for the obvious reason that we are adding food.  This might seem unimportant for the lives of most dogs who are fed to the point of obesity, however in behavior research, most animals are deprived of food before reinforcement begins in learning paradigms, therefore the contingency of food as positive reinforcement is being given to an animal deprived of enough food prior to testing to cause a 15% decrease in body mass.  For perspective, imagine a 180-pound male losing 27 pounds before being handed a cheeseburger as reinforcement and you might appreciate how removing deprivation is not only perhaps a better description of the actual science of reinforcement but also a significant motivator for a rat to start pressing levers in their black box.

A classic example used popularly in psychology textbooks is the example of an aspirin as a negative reinforcement. The idea is that the removal of a headache might increase future aspirin-taking behavior, thus the removal of the aversive headache could be said to increase the frequency of the behavior—or more concisely, the aspirin is negatively reinforcing aspirin-taking behavior. However, we are adding aspirin to the system, so what do we say about the addition of a stimulus that causes the removal of another stimulus that overall causes a consequence which increases or decreases the frequency of the antecedent behavior? Vis-à-vis “aspirin-logic,” the addition of food that removes the feeling of hunger would have to be negative reinforcement as well.  By now it should be clear that there is no mutual exclusivity to the reasoning behind the popular interpretations of the quadrants of operant conditioning, and therefore any conclusion that relies on such a demarcation is neither logical nor scientific.  Simply put, analyzing behavior with a system that relies on the Tweedledee-Tweedledum characterization of reinforcement and punishment (Marr, 2006) in a universe that is beholden to the conservation of energy is a product of improper, massive oversimplification.

It should be appreciated that the difficulty of negotiating positive versus negative effects within a system is common to science.  For example, biologists that enjoy old-fashioned terminology will describe the movement of an organism in relationship to a stimulus a “taxis;” positive taxis is therefore movement toward a stimulus, while negative taxis is movement away from a stimulus. If the reference point for the behavior is the change to the environment (e.g. the appearance of a prey animal) then naturally we would instinctively describe the motion of a predator towards the prey as positive taxis. However, let us instead change the animal to an herbivore like an elk. Imagine a large group of elk munching away on some delicious savory grass. Overtime, the elk wear down the presence of grass in the area they are feeding and they then move toward another area which has more grass present. Are the elk moving toward an area of more food to forage on or away from an area of less food to forage on (i.e. is it positive taxis toward new grass or negative taxis away from no grass)?

It is important to remember that much of what we use to categorize nature are simply conventions, and sometimes their creation is no more sophisticated than what one person decided while reading the latest issue of Science while sitting on the can. One of my favorite illustrations of the sometimes arbitrary nature of conventions is in the way physicists describe torque motions. In physics, a torque that generates movement counterclockwise is notated with a positive force and a torque that generates movement clockwise is notated with a negative force. Why? Because if you replicate the motion of an object moving counterclockwise with your fingers on your right hand, your thumb is pointing up, and if you replicate the motion of an object moving clockwise with your fingers on your right hand, your thumb is pointing down. For this reason it is called the thumb rule.

ImageDespite the overwhelming issue, research papers and essays are still frequently published describing events that are “positive reinforcement” or “negative reinforcement,” therefore this is by no means just a dog industry issue.  Furthermore, responses to these criticisms fail in addressing the issue head on, are unable to provide sound counterarguments, and/or fall back on the pragmatic argument: “well, we don’t have anything better so it is better than nothing.” There are a couple problems with the pragmatic argument. First, define what is “better?” Quadrants create a paradigm view that cannot be supported without the existence of quadrants, so if “better” requires a convention that maintains the theory-laden beliefs of operant conditioning then I would say the pragmatists are correct, just like creationism cannot exist without a God who created the universe as the central hypothesis.  If “better” requires only the need to describe learning events then the pragmatists are definitively wrong because the concepts of reinforcement and punishment are descriptive enough in and of themselves as positive/negative distinctions always have to be clarified further with methodological explanation.

But all of this side steps the heart of the issue: harsh punishment creates the negative and deleterious results we are familiar with because of the threat it presents to the organism.  The ethics here are measured through actual harm, not through the way an animal learned something. Indeed, many dogs might not learn much of anything that is objectively quantifiable in an operant classification after being swung around on a choke chain in a helicopter swing or kicked in the ribs, thus we couldn’t say these events belong to any quadrant because we have to first establish the learned behavior that is operating on the environment.

Ethics does not have a quadrant. It is a complex web of issues that are rarely cut and dry and conversations about dog training through positive and negative quadrant distinctions only obfuscate the discussion at hand. Kicking a dog is unethical because it is harmful and cruel: not because it is “positive punishment.” Dangling a dog in the air as it suffocates is unethical because it too is harmful, cruel and abusive. You cannot design an experiment to show that the Yankees won is true but the Red Sox lost is false in the same way it is impossible to falsify whether it is the addition of a treat or the removal of hunger acting during a learning event. Pragmatists will say “oh, whatever, it’s not a big deal because I know the difference.” Problematically, it’s not only unhelpful to the conversation but it is also unscientific. Science is falsifiable, if it is not, it is not science.

ImageReferences:

Baron, A., & Galizio, M. (2005). Positive and negative reinforcement: Should the distinction be preserved? The Behavior Analyst / MABA, 28(2), 85–98.

Baron, A., & Galizio, M. (2006). The distinction between positive and negative reinforcement: Use with care. The Behavior Analyst, 29(1), 141.

Marr, M. J. (2006). Through the Looking Glass: Symmetry in Behavioral Principles? The Behavior Analyst, 29(1), 125.

Michael, J. (1975). Positive and Negative Reinforcement, a Distinction That Is No Longer Necessary; Or a Better Way to Talk about Bad Things. Behaviorism, 3(1), 33–44.

Tonneau, F. (2007). Behaviorism and Chisholm’s Challenge. Behavior and Philosophy, 35, 139–148.

Weiss, B., & Laties, V. G. (1961). Behavioral Thermoregulation. Science, 133(3464), 1588–1588. doi:10.1126/science.133.3464.1588

Are dogs and wolves the same species?

The question of whether dogs and wolves are members of the same or different species is a controversial one.  To begin with, species classification is a convention used to help aid in our ability to organize nature and it is anything but definitively objective.  This should not decrease the importance of classifying species, but before we begin to try and understand the question, we will benefit from understanding that the nature of the question is very philosophical.  Always keep in the back of your mind that the personal preference of an individual will always be influential in subjective conclusions.  Therefore, to try and be objective about the conversation I would like to discuss the big picture, and in biology, the big picture is always evolution.

Evolution is often described as cumulative processes so slow that they take between thousands and millions of decades to complete (e.g. Dawkins, 1986).  This is only part of the picture.  We certainly have an in-depth archeological fossil record that shows gradual changes in species over millennia (such as the development of feathers in dinosaurs or the eye-migration of flatfish), however biological changes can also happen in the wink of an eye—at least compared to traditionally conceptualized evolutionary timescales.  Most simply, evolution can be defined as change over time.  But what kind of change?  Does any change constitute evolution? Does any duration sufficiently qualify for “time?”  These are important considerations because whatever definition is chosen will create a first premise assumption from which any arguments will flow from—like the way the lens of a camera manipulates light before entering the camera body and forming an image, so too can a first premise assumption influence our perceptions so that our observations fit a desirable theory instead of the natural phenomenon.

Some evolution happens very slowly (such as the previously mentioned examples of feathers in dinosaurs and the eye-migration of flatfish); however, these changes arose most probably due to mutation and sexual selection, not because these changes condoned a functional advantage in evading hazards or finding food.  Most examples of evolution are due to a change in the characteristics of a group that enable it to survive, thus evolution can be viewed in this light as a response to changes in the environment.  Typically, environments change very slowly and significant changes often ride on the back of natural disasters.  The evolution of dinosaurs into birds was due to a two-fold catastrophe.   Approximately 200 million years ago, atmospheric oxygen declined nearly 20% causing one of the largest extinction periods in Earth’s history (Berner et al., 2006).  This killed off an unprecedented amount of land dwelling animals and threatened aquatic living organisms as well.  For example, some species of fish such as tuna evolved ram-air induction (whereby swimming at high velocity forced water across the gills at a higher speed to ensure maximum oxygen diffusion from water).  As if global suffocation wasn’t bad enough, to add insult to injury, an asteroid the size of Manhattan slammed into Mexico just a few millennia later.  These two factors meant that the only dinosaurs which survived were small and could fly—what we call birds.  Predominantly, it is important to remember that changes to the environment are what drive these kinds of selection processes, especially when these changes create significant mortality rates—a concept I will return to later.

The controversy over the classification of dogs and wolves can be seen on numerous levels, but one that stands out for me is the way in which many wolf-dog hybrid enthusiasts are very passionate that the correct term is not “hybrid” but “wolf dog”—since both the dog (Canis lupus familiaris) and the wolf (Canis lupus lupus) are according to some scientists taxonomically sub-species of Canis lupus.  While this is a relatively recent distinction (originally, Carl von Line classified the dog as Canis familiaris, a different species than the wolf) the taxonomic nomenclature does not determine whether the mating of two animals qualifies as a hybrid.  Hybridization is the interbreeding of individuals from genetically distinct populations, regardless of their taxonomic status (Stronen & Paquet, 2013).  Wolves and dogs may be amazingly similar in their genetics, however they are clearly genetically distinct populations (e.g. vanHoldt et al., 2011).

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Principal component analysis of all wolf-like canids for the 48K SNP data set: PC1 represents a wild versus domestic canid axis, whereas PC2 separates wolves (n=198) and dogs (n=912) from coyotes (n=57) and red wolves (n=10). Result shows dogs and gray wolves are genetically distinct (Fst=0.165). PC2 in this analysis of the data demonstrate a geographically based population hierarchy within gray wolves and coyotes (vanHoldt et al., 2011)

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Plots show ancestry blocks and their assignments for representative individuals of canid populations with average size of blocks, percent ancestry, and number of generations since most recent admixture (t) indicated. Two-ancestor (coyote, A; gray wolf, B) analyses are presented for a Great Lakes wolf from Minnesota (C), a captive red wolf (D), and an Algonquin wolf (E). Three-ancestor analyses (coyote, A; gray wolf, B; dog, F) are presented for a Northeastern coyote from Vermont (G), a Southern coyote from Louisiana (H), and a Midwestern coyote from Ohio (I) – (vanHoldt et al., 2011)

The supposedly infallible “fact” that dogs are descended from wolves took the world by fire with research into mitochondrial DNA and a publication which appeared in Science titled “Multiple and Ancient Origins of the Domestic Dog” (Vila et al., 1997).  In this paper, the authors concluded that dogs were 135,000 years old—a conclusion which is sheer nonsense (Larson, 2011; Larson et al., 2012).  Over the last decade, geneticists have published paper after paper pointing at different dates and different locations for domestication with very little consensus but most supporting the conclusion that dogs are direct descendants of the wolf.  One important reason for this is because the methodology behind examining mitochondrial DNA (mtDNA) has a very debilitating first premise assumption: that the rate of mtDNA mutation is constant in dogs and wolves despite a massive wolf population bottleneck and an exploding dog population.  This is a problem because both of these population effects cause genetic drift.  Imagine if you take a population and reduce it to a mere handful.  How do you tell whether you are looking at the first members of a new species or the surviving members after a population endangerment?  Likewise, imagine taking two dogs and deciding you will start your own breed.  If your new breed goes through a population explosion, then their DNA will make up a unrepresentative sample of the historical population (this is called the “founder effect”).

Genetic research is awesome, don’t get me wrong, and it cannot be underappreciated that innovations in genetics have opened up wildly exciting new scientific avenues of investigation into organisms.  However, genetic analysis is relatively new to the question of speciation in the animal kingdom and some insight to the Canis lupus dilemma can be gained by looking at the overall ecology of dogs and wolves instead of just their sequence of nucleic acids.  Research that examines genotypes, high-density single nucleotide polymorphisms, epigenetic methylations, mitochondrial DNA, etc., is literally a whole new world, but it is not the whole picture.  The expression of a plant or animal’s DNA is what creates its phenotype (from morphology to behavior), and it is the phenotype that is thus selected for in the environment and we can learn lots by simply examining the phenotype in and of itself.

As previously mentioned, when two genetically distinct species reproduce the offspring is called a hybrid.  However in animals, hybridization is a pretty big deal.  When sperm meets egg, a zygote is formed, thus ecologists look at both prezygotic (before reproduction) and postzygotic (after reproduction) barriers that make hybridization difficult.  Examples of prezygotic barriers include: habitat isolation (where two species are geographically isolated, sometimes living in the same area but rarely meet), behavioral isolation (where two species do not recognize the signals/mating cues of each other or employ different foraging strategies), temporal isolation (where one species might breed in the spring while another breeds in the fall), mechanical isolation (where the “wedding tackle” of one species doesn’t fit in the “hoo-ha” of another species), and genetic isolation (where the sperm and egg of two species are unable to form a zygote).  Postzygotic barriers include reduced hybrid viability (where hybrids fail to develop or reach sexual maturity), reduced hybrid fertility (e.g. mules are hybrids of horses and donkeys and are all sterile), and hybrid breakdown (where the offspring of hybrids have further reduced viability and/or fertility).

The behavioral isolation of dogs and wolves is astronomical because behaviorally there are almost no commonalities between them.  In fact, leaving dogs aside for a moment, very important behavioral distinctions exist just between different groups of wolves that affect their offspring viability (postzygotic barriers).  For example, one of the most important criteria for mate preference in wolves comes down to hunting strategies: wolves with similar hunting and foraging strategies are more likely to mate and teach these strategies to their offspring.  Foraging behavior is a phenotypical characteristic that plays a major role in determining the ecological niche of a species—so much so that wolves who employ different foraging strategies also display different types of social relationships.

Very few dogs hunt for food.  Even in societies which still use dogs for hunting (such as the indigenous Mayagna people of Nicaragua), dogs rarely make the kill.  Their role in the hunt is to bring an animal to ground and make a loud ruckus until the humans can find it and make the killing blow with their machete.  In this capacity, dogs are pound for pound as efficient as a rifle in bringing in meat for the indigenous people of Nicaragua, and the dogs benefit by being given leftovers (Koster, 2008).  It is certainly true that some dogs (some) opportunistically take down and on occasion eat small animals such as rats, possums, cats, etc.  However, dogs like other scavengers fill an important role in the grand ecological picture regarding the flow of biomass (Wikenros et al., 2013).

Hunting in the wild is simply not an available strategy for dogs to survive.  One important reason for this is that the energy dogs would expend to take down and eat small prey animals would be much greater than the energy gained by hunting them.  This is illustrated with African wild dogs (Lycaon pictus), who pound for pound hunt, kill, and consume more meat than any other predator in Africa—this is not because they are greedy, this is because of their metabolic needs.  When you look at African wild dogs, small prey like African hares make up only an average profitability of 0.6kg per hunt (4.8kg per kilometer chased), whereas Wildebeest weighing approximately 100kg make a profitability of 35.2kg per hunt (51kg per kilometer chased).  African Wild dogs not only make significantly more meat off of larger prey animals, but they also have a higher success catching them than they do small animals like African hares (38% success versus 31%) (see Creel & Creel, 1995 for Lycaon pictus data).  If humans were to go extinct tomorrow, dogs could never fill the role of these kinds of predators.  Simply put, dogs are more likely to try and play with a deer than to try and kill it.

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Trophic diagram of organisms in relation to predators since reintroduction (Freeman et al., 2013)

As if there is very little difference, dogs are frequently labeled carnivores like their wolf cousins (implying a predatory nature); however ecological foraging models are much more nuanced than simply whether or not the food consumed is animal or plant-based.  Dogs are detritivores (i.e. scavengers—animals which live off of dead food sources).  Whether it is the kibble we drop in the bowl, the dump which feral dogs scavenge at, or even raw meat or table scraps being tossed from the table, dogs do not kill their food.  Whether feral or companion pet, the dog’s niche relies on their ability to live in close proximity to humans—a quality which is typically severely impacted by interbreeding with wolves.  Dogs utilize a very different and elongated socialization period that enables them to develop interspecies social bonds much easier (Lord, 2013), and thus the viability of hybrid offspring between dogs and wolves is severely impacted through both prezygotic and postzygotic barriers.  Quite simply, just because two animals are capable of interbreeding, claiming they are the same species does not make sense in light of almost all aspects of their phenotype outside of morphology (and even then, calling a Chihuahua a wolf is simply absurd).

Thinking about the foraging strategy of the dog as more closely related to fungi, archaea, worms, and dung beetles as opposed to the apex predator wolf might seem rather unglamorous, however in truth it highlights their ecological and evolutionary success.  All life is built on the need for energy and nutrients.  Energy needed for life comes from the sun, regardless of the species.  Plants use the energy from photons to produce sugar, which is natures way of storing energy from the sun.  For this reason, plants are termed “producers” because they create available energy and nutrients for other organisms (such as hydrogen, carbon, nitrogen, oxygen and phosphorus—among other nutrients).  Through nutrients, organisms manipulate the stored energy and use it to produce proteins that enable the organism to survive and reproduce.  The availability of these resources on a large scale is quantified in ecology as Net Primary Productivity (NPP).

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Data: NASA
Image: Freeman et al., 2013

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Image: Freeman et al., 2013

NPP is essentially a quantification of the available resources organisms need to survive.  If you look on the map above, you will see that NPP is highest in the tropics and lowest in the tundra.  The niche of the wolf, compared to the tropics, is in regions of the world where NPP is strikingly low—emphasizing their need to hunt and kill large prey.  Humans appropriate 24% of the NPP of the entire planet.  Think about that for a moment… nearly one-quarter of all available energy on the planet, yet we are just one of thousands if not millions of species cohabitating this blue ball in our corner of the solar system.  We can appreciate that with the laws of the conservation of energy, large consumption leads to large waste, waste that is still rich with hydrogen, carbon, nitrogen, sulfur and phosphorus.  While dogs most certainly share a common ancestor with the wolf, their emergence as a species is due to the tremendous advantage of having proximity to the largest appropriation of nutrients on the planet.  Coppinger has long emphasized the difference between “domestic” (living amongst humans) and “domesticated” (made to live amongst humans).  With no evidence that humans were ever sophisticated enough to establish breeding programs to artificially select for tame qualities like the silver fox experiment, it is not logical to believe that dogs could have emerged through careful pup selection.  Even today, it is extremely difficult to create human-socialized wolves (who still behave nothing like dogs) and inbreeding is an enormous issue within current populations—how would humans have overcome these issues when we still hadn’t become sophisticated enough to harness agriculture?

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Data: Vince, 2011
Image: Freeman et al., 2013

It is hard to imagine that sometimes we forget just how much we have changed this planet.  If the consumption of nearly 25% of the planet’s NPP doesn’t make you think for a moment, then consider that 90% of all mammalian biomass on the planet consists of humans and domesticated animals.  10,000 years ago, this number was approximately 0.1%.  While rambling around since approximately 200,000 years ago, human population did not reach one billion until 1804.  By 1927, human population reached two billion.  1960: three billion.  1974: four billion.  1987: five billion.  1999: six billion.  By the year 2011, human population reached seven billion (population data and biomass percentages taken from Vince, 2011).  In parallel with increasing human population, it is estimated that there are approximately one billion dogs around the world now, whereas wolves are on the brink of extinction.  At this rate, it is only a matter of time before human population will exceed the appropriable NPP of the planet and very few undomesticated species will exist outside of detritivores feeding on human waste as the human population crashes into unsustainability.

The story is very romantic: man and wolf, hunting and foraging together.  Unfortunately there is simply no evidence; and if I’m being charitable, the probability that dogs evolved directly from grey wolves is extremely unlikely.  While many similarities are perceived to exist between dog and wolf, upon closer examination, the similarities are almost impossible to find.

References:

Berner, R. A., VandenBrooks, J. M., & Ward, P. D. (2007). Oxygen and Evolution. Science, 316(5824), 557–558. doi:10.1126/science.1142654

Brucker, R. M., & Bordenstein, S. R. (2012). Speciation by symbiosis. Trends in Ecology & Evolution, 27(8), 443–451. doi:10.1016/j.tree.2012.03.011

Creel, S., & Creel, N. M. (1995). Communal hunting and pack size in African wild dogs, Lycaon pictus. Animal Behaviour, 50(5), 1325–1339.

Freeman, S., Quiliin, K., & Allison, L. (2013). Biological Science (5th edition.). Benjamin Cummings.

Koster, J. M. (2008). Hunting with Dogs in Nicaragua: An Optimal Foraging Approach. Current Anthropology, 49(5), 935–944. doi:10.1086/595655

Larson, G. (2011). Genetics and Domestication: Important Questions for New Answers. Current Anthropology, 52(S4), S485–S495. doi:10.1086/658401

Larson, G., Karlsson, E. K., Perri, A., Webster, M. T., Ho, S. Y. W., Peters, J., … Lindblad-Toh, K. (2012). Rethinking dog domestication by integrating genetics, archeology, and biogeography. Proceedings of the National Academy of Sciences, 109(23), 8878–8883. doi:10.1073/pnas.1203005109

Lord, K. (2013). A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris). Ethology, 119(2), 110–120. doi:10.1111/eth.12044

Rousset, F., & Solignac, M. (1995). Evolution of single and double Wolbachia symbioses during speciation in the Drosophila simulans complex. Proceedings of the National Academy of Sciences, 92(14), 6389–6393.

Stronen, A. V., & Paquet, P. C. (2013). Perspectives on the conservation of wild hybrids. Biological Conservation, 167, 390–395. doi:10.1016/j.biocon.2013.09.004

Vince, G. (2011). An Epoch Debate. Science, 334(6052), 32–37. doi:10.1126/science.334.6052.32

vonHoldt, B. M., Pollinger, J. P., Earl, D. A., Knowles, J. C., Boyko, A. R., Parker, H., … Wayne, R. K. (2011). A genome-wide perspective on the evolutionary history of enigmatic wolf-like canids. Genome Research, 21(8), 1294–1305. doi:10.1101/gr.116301.110

Wikenros, C., Sand, Hã¥., Ahlqvist, P., & Liberg, O. (2013). Biomass Flow and Scavengers Use of Carcasses after Re-Colonization of an Apex Predator. PLoS ONE, 8(10), e77373. doi:10.1371/journal.pone.0077373

Blogging Down Our Brains

“By giving us the opinions of the uneducated, journalism keeps us in touch with the ignorance of the community.” – Oscar Wilde

Anyone interested in furthering his or her knowledge of a subject is faced with a depressing enigma: the amount of bad information outnumbers the amount of good information.  As a person who lives life trying to acquire a deeper understanding of the world, bad information really pisses me off.

Recently, a blog was published titled “5 Incredible Ways Dogs Can Read Your Mind” (Emery, 2013).  In it, the author presents several claims to support the premise that dogs can read our minds.  Formally, this is referred to as Theory of Mind, which Emery defines as the “understanding that other beings have different perceptions, and that those perceptions can be valuable” (Coren, 2011a).  This is wrong.  To be fair, even scientists do not always define it accurately, however choosing a blogger to reference who actually took the time to read the conclusions and discussions of the studies they were reviewing might have been a beneficial start.

The correct definition:

Theory of mind is the ability to make accurate inferences to understand the behavior of other animals because of abstract (theory-like) representations of the causal relationship between unobservable mental states and observable behavior (Premack & Woodruff, 1978, as cited in Penn & Povinelli, 2007—emphasis my own).

More concisely, theory of mind requires the ability to know that the behavior of another animal is a product of their cognitive state—this is distinctly different from responding to environmental factors, including that of an animal’s behavior (Udell & Wynne, 2011).  While many authors have described theory of mind as dated and potentially no longer useful (e.g. Horowitz, 2011), the goal of this blog isn’t to provide alternative evidence as to whether or not theory of mind is a valid concept in non-human animals such as dogs—best to let that war rage on in the academic community.  Instead, this blog is two-fold: 1) to correct the dirge of fallacies that went viral with Emery’s blog and 2) to use it as a model for understanding how important the source of information is.  With that as our base, let’s start at the top.  If you haven’t read the blog I am referring to yet, here is the link.

Note: the titles of each section below correlate to the paragraph titles of Emery’s blog and are here to give sign posts regarding what statements I am pulling apart: they are not claims I am making.

#5: Dogs are Capable of Empathy

“Yawning is a phenomenon directly connected to empathy, and as such has only been found to occur in species capable of empathizing (i.e. humans, and other primates), and only then within a single species.” (Emery, 2013)

First, yawning behavior is widespread and believed to be common to ALL vertebrates: including mammals, birds, fish, amphibians and reptiles (Baenninger, 1997).  Second, there are EIGHT different hypotheses regarding the function of yawning, if it is indeed even functional, and so the communication (empathy) hypothesis is just one of several ‘stabs’ at why animals yawn (Guggisberg et al. 2010).  Problematically, the communication hypothesis is not unilaterally supported and the studies that do support it are plagued with a lack of controls to rule out competing hypotheses that would be direct confounds to the results.  Even if we accepted that contagious yawning as a function of empathy was viable and true, researchers employing more stringent methods have been unable to conclude that dogs show signs of contagious yawning behavior (Harr et al., 2009).

“So obviously dogs have an uncanny ability to read our emotions … but how? Well, it’s because all humans, whether right- or left-handed, display our emotions predominantly on the right side of our faces.” (Emery, 2013)

You’d think with a 50/50 chance she might have gotten this one right merely by dumb luck—but no, humans display their emotions predominantly on their LEFT side, not their right (Borod et al. 1997).  Regardless of problems between lefts and rights, associative learning is an alternate explanation for any gaze bias observed in dogs.  However, perhaps ironically, it could even be argued that if dogs could read our mind, then they wouldn’t need to check in with the more emotional side of our face to know if we are just slightly angry about the Christmas ham getting eaten, or really angry.  Empathy is an equally hot topic as theory of mind and definitions historically have tended to overlap—often stressing the importance of “cognitive perspective taking” (Davis 1983).  Despite the sticky separation of these concepts, empathy refers to the ability of one individual to infer and share the emotional spectrums of another (Gallese, 2003; Völlm et al., 2006).  Thus, regarding whether or not non-human animals have empathy, gaze research simply cannot possibly answer the question.

#4: Dogs Understand That Your Visual Perspective Is Different from Their Own

Yes, they do, but does this constitute evidence that they possess theory of mind?  Opponents to the “perspective taking” element supporting theory of mind make a compelling counterargument: simply that all animals learn.  If a moose walks into a tree, they do not turn around and walk the other way because at some point in their life they learned they could walk around it.  A group of gazelles foraging and scanning the environment have learned to scan for predators because being eaten by a cheetah sucks.  A prey animal thus wouldn’t survive very long without some knowledge of potential threats in the environment.  Knowing this, if a gazelle stops eating, freezes, and looks across the field, the fact that all the gazelles are likely to stop foraging and check for danger does not prove the presence of theory of mind, because alternatively they could be responding due to empirical knowledge that it is in their interest to keep a look out for hungry kittens.

If you’re walking along the street and you see someone looking up, we are likely to look up as well.  The novelty of seeing someone looking up is a pretty strong stimulus to evoke our social facilitation (looking up as well), just like the gazelle and their knowledge that the environment contains dangers to be aware of, we understand that pianos or stock brokers falling on our head is also likely to put a dent in our afternoon.

Many researchers have demonstrated how dogs and wolves have varying abilities to search around visual barriers (e.g. Bräuer et al., 2004; Range et al., 2011; Virányi et al., 2009); however, ultimately here is what you have to decide for yourself:

  1. The dog is reading your mind and knows that you are looking at an object around the corner
  2. The dog notices that your eyes are looking somewhere to their right or left (an observable behavior) and is curious to investigate – oh there is a barrier?  Hmmm, let me walk around that

I think this research is interesting, but even so, this does not constitute evidence for theory of mind because it does not rule out competing hypotheses; such that a dog could be simply taking information from a visual environment—not attenuating to the cognitive states to understand the causal relationship between unobserved mental states and observed behavior.  Just my opinion, argument 2 seems much more practical and is further supported by our understanding that dogs are extremely sensitive to gazing since it is one of the most common signals they use in agonistic (conflict) behavior.

More egregiously though, Emery continues and states that dogs will abandon all morality and go for a piece of food the second you close your eyes, or turn your back, or place a barrier between you and the food, and this is a complete misinterpretation to the research done on this phenomena and thus absolute gibberish.  Leaving a food item alone is trainable.  Browse around YouTube and you will find plenty of videos where a dog is told to wait before his or her dinner bowl is set down, and then the owner walks out of the room, or even the house, before returning to release the dog to eat the food.  Honestly, a solid ‘leave it’ is one of the easiest behaviors to train, so this kind of research has to be interpreted very carefully regarding what it actually means, if anything, for the lives of our dogs.

#3 Dogs Assume That You Know Something They Don’t

As if I wasn’t already pounding my head against the desk, the author then uses the observation that dogs want to eat what we are eating as support for doggie mind reading abilities.  Unfortunately, this is not a trait unique to dogs (or humans for that matter).  Many social mammals select food preference by their group’s behavior.  For example, rats learn from group members how to determine what to eat and will learn to avoid the smell of poisoned food, a neophobic response—this is one of the reasons why rat poison doesn’t eliminate rat populations (Galef & Clark, 1971).  It is a fascinating behavior, but it does not require mind reading—rather rudimentary social facilitation.

#2 Dogs Understand Pointing

“…but the fact of the matter is that dogs and humans are the only two species currently clinging to our big blue spaceball who understand the point of pointing.”  (Emery, 2013)

Other than wolves (Udell et al., 2008), cats (Miklosi et al., 2005), parrots (Giret et al., 2009), bats (Hall et al., 2011), Jackdaws (Von Bayern & Emery, N., 2009), goats (Kaminski et al., (2005), dolphins (Pack & Herman, 2004), fur seals (Scheumann & Call, 2004), Ravens (Schloegel et al., 2007; for a review, see Udell et al., 2012)… hmm, only two species you say?  Monty Python jokes about the Spanish Inquisition aside, the ability for an animal to learn that they can walk around a tree is no different from the ability to learn that a finger might be directing towards food.  Animals who learn this distinction are socialized to people—period.  Nobody has snatched a dog that has never seen a human, tossed it in a room, pointed at a cup with food inside, and seen the dog dive in and say “thank you master!”  No, it would be shaking in the corner terrified for its life.  Animals who have been socialized to humans respond to pointing and other human communicative gestures (e.g. gazing and pointing with foot): pick your species.  Variance in this skill can be as easily explained by the failure for many animals to follow directions (just ask any school teacher how many times they have to remind students to write their name at the top of a test).

inquisition

#1 Dogs Know When You Like Someone Else More

Finally, Ms. Emery claims that oxytocin is a “love- and jealousy-related hormone” (Coren, 2011b).  This claim comes from a single study involving humans playing a computer game (Shamay-Tsoory et al., 2009), however the conclusions the authors make can be reinterpreted to fit the standard functional understanding of oxytocin (Tops, 2010).  Oxytocin is a mammalian hormone that triggers milk letdown in nursing females and is involved in a wide variety of social behaviors: such as increasing pleasure during orgasm, increasing time of social contact, facilitating memory of sexual partners, protects fetal neurons from injury during delivery, improves navigational strategies, and works with vasopressin receptors to aid pair-bonding (Breedlove et al., 2010).

If you don’t see references: assume the author is an idiot

It should be clear by now that cracked.com might be just about the worst source for dog behavior science, and if you have been following some of the citation trails, Psychology Today might appear as a questionable source as well.  There are more authors writing books and blogging about dogs than there are dogs in family homes and they range from people with high school diplomas to PhDs. Citations and a reference list is an excellent way to begin to decipher the quality of information, however it is not everything either.

While bad information frustrates the daylights out of me, ultimately, the burden falls on the consumer to be sure to examine the evidence. This is one of many reasons why a list of references is so important, and why it is best to assume the author is likely an idiot if they don’t bother to acknowledge the sources of their information in a clear, concise reference section at the end.  If there is no reference list, than be sure to ask yourself whether you believe you are reading an opinion piece or an opinion piece veiled as accurate science.

References:

Baenninger, R. (1997). On yawning and its functions. Psychonomic bulletin & review, 4(2), 198–207.

Bräuer, J., Call, J., & Tomasello, M. (2004). Visual perspective taking in dogs (Canis familiaris) in the presence of barriers. Applied Animal Behaviour Science, 88(3–4), 299–317. doi:10.1016/j.applanim.2004.03.004

Breedlove, S. M., Watson, N. V., & Rosenzweig, M. R. (2010). Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience, Sixth Edition (6th ed.). Sinauer Associates, Inc.

Borod, J. C., Haywood, C. S., & Koff, E. (1997). Neuropsychological aspects of facial asymmetry during emotional expression: A review of the normal adult literature. Neuropsychology Review, 7(1), 41–60.

Coren, S. (2011a). Can Your Dog Read Your Mind? Retrieved September 23, 2013, from http://www.psychologytoday.com/blog/canine-corner/201106/can-your-dog-read-your-mind

Coren, S. (2011b). Do Dogs Feel Jealousy and Envy? Retrieved September 23, 2013, from http://www.psychologytoday.com/blog/canine-corner/201111/do-dogs-feel-jealousy-and-envy

Davis, M. H. (1983). Measuring individual differences in empathy: Evidence for a multidimensional approach. Journal of Personality and Social Psychology, 44(1), 113–126. doi:10.1037/0022-3514.44.1.113

Emery, L. (2013). 5 Incredible Ways Dogs Can Read Your Mind.  Retrieved September 23, 2013, from http://www.cracked.com/article_20572_5-incredible-ways-dogs-can-read-your-mind.html

Galef, B. G., & Clark, M. M. (1971). Social factors in the poison avoidance and feeding behavior of wild and domesticated rat pups. Journal of Comparative and Physiological Psychology, 75(3), 341–357. doi:10.1037/h0030937

Gallese, V. (2003). The roots of empathy: the shared manifold hypothesis and the neural basis of intersubjectivity. Psychopathology, 36(4), 171–180. doi:72786

Giret, N., Miklósi, Á., Kreutzer, M., & Bovet, D. (2008). Use of experimenter-given cues by African gray parrots (Psittacus erithacus). Animal Cognition, 12(1), 1–10. doi:10.1007/s10071-008-0163-2

Guggisberg, A. G., Mathis, J., Schnider, A., & Hess, C. W. (2010). Why do we yawn? Neuroscience & Biobehavioral Reviews, 34(8), 1267–1276. doi:10.1016/j.neubiorev.2010.03.008

Hall, N. J., Udell, M. A. R., Dorey, N. R., Walsh, A. L., & Wynne, C. D. L. (2011). Megachiropteran bats (Pteropus) utilize human referential stimuli to locate hidden food. Journal of comparative psychology (Washington, D.C.: 1983), 125(3), 341–346. doi:10.1037/a0023680

Harr, A. L., Gilbert, V. R., & Phillips, K. A. (2009). Do dogs (Canis familiaris) show contagious yawning? Animal Cognition, 12(6), 833–837. doi:10.1007/s10071-009-0233-0

Horowitz, A. (2011). Theory of mind in dogs? Examining method and concept. Learning & Behavior, 39(4), 314–317. doi:10.3758/s13420-011-0041-7

Kaminski, J., Riedel, J., Call, J., & Tomasello, M. (2005). Domestic goats, Capra hircus, follow gaze direction and use social cues in an object choice task. Animal Behaviour, 69(1), 11–18. doi:10.1016/j.anbehav.2004.05.008

Miklósi, Á., Pongrácz, P., Lakatos, G., Topál, J., & Csányi, V. (2005). A Comparative Study of the Use of Visual Communicative Signals in Interactions Between Dogs (Canis familiaris) and Humans and Cats (Felis catus) and Humans. Journal of Comparative Psychology, 119(2), 179–186. doi:10.1037/0735-7036.119.2.179

Pack, A. A., & Herman, L. M. (2004). Bottlenosed dolphins (Tursiops truncatus) comprehend the referent of both static and dynamic human gazing and pointing in an object-choice task. Journal of comparative psychology (Washington, D.C.: 1983), 118(2), 160–171. doi:10.1037/0735-7036.118.2.160

Penn, D. C., & Povinelli, D. J. (2007). On the lack of evidence that non-human animals possess anything remotely resembling a “theory of mind.” Philosophical Transactions of the Royal Society B: Biological Sciences, 362(1480), 731–744. doi:10.1098/rstb.2006.2023

Range, F., & Virányi, Z. (2011). Development of Gaze Following Abilities in Wolves (Canis Lupus). PLoS ONE, 6(2), e16888. doi:10.1371/journal.pone.0016888

Scheumann, M., & Call, J. (2004). The use of experimenter-given cues by South African fur seals (Arctocephalus pusillus). Animal cognition, 7(4), 224–230. doi:10.1007/s10071-004-0216-0

Schloegl, C., Kotrschal, K., & Bugnyar, T. (2008). Do common ravens (Corvus corax) rely on human or conspecific gaze cues to detect hidden food? Animal cognition, 11(2), 231–241. doi:10.1007/s10071-007-0105-4

Shamay-Tsoory, S. G., Fischer, M., Dvash, J., Harari, H., Perach-Bloom, N., & Levkovitz, Y. (2009). Intranasal Administration of Oxytocin Increases Envy and Schadenfreude (Gloating). Biological Psychiatry, 66(9), 864–870. doi:10.1016/j.biopsych.2009.06.009

Tops, M. (2010). Oxytocin: Envy or Engagement in Others? The Striatum, Psychopathy, and Molecular Mechanisms of Addiction, 67(1), e5–e6. doi:10.1016/j.biopsych.2009.08.032

Udell, M. A. R., Dorey, N. R., & Wynne, C. D. L. (2008). Wolves outperform dogs in following human social cues. Animal Behaviour, 76(6), 1767–1773. doi:10.1016/j.anbehav.2008.07.028

Udell, M., & Wynne, C. (2011). Reevaluating canine perspective-taking behavior. Learning & Behavior, 39(4), 318–323. doi:10.3758/s13420-011-0043-5

Udell, M. A., Spencer, J. M., Dorey, N. R., & Wynne, C. D. (2012). Human-socialized wolves follow diverse human gestures and they may not be alone. Int. J. Comp. Psychol, 25, 97–117.

Virányi, Z., Gácsi, M., Kubinyi, E., Topál, J., Belényi, B., Ujfalussy, D., & Miklósi, Á. (2008). Comprehension of human pointing gestures in young human-reared wolves (Canis lupus) and dogs (Canis familiaris). Animal Cognition, 11(3), 373–387. doi:10.1007/s10071-007-0127-y

Völlm, B. A., Taylor, A. N. W., Richardson, P., Corcoran, R., Stirling, J., McKie, S., … Elliott, R. (2006). Neuronal correlates of theory of mind and empathy: A functional magnetic resonance imaging study in a nonverbal task. NeuroImage, 29(1), 90–98. doi:10.1016/j.neuroimage.2005.07.022

Von Bayern, A. M. P., & Emery, N. J. (2009). Jackdaws Respond to Human Attentional States and Communicative Cues in Different Contexts. Current Biology, 19(7), 602–606. doi:10.1016/j.cub.2009.02.062

Stress and learning

The Yerkes-Dodson Law

In 1908, Yerkes and Dodson published findings of a remarkable phenomenon they discovered regarding the relationship between arousal and performance.  The law asserts:

  1. The speed of learning and performance increases with arousal; however, it quickly reaches an optimal intensity where learning and performance then deteriorate.
  2. Both weak stimuli and strong stimuli result in slow habit-formation.
  3. The more difficult the task, the lower the optimal level of arousal for maximum performance.
  4. “A stimulus whose strength is nearer to the [minimum] threshold than to the point of harmful stimulation is most favorable to the acquisition of a habit.”  (Yerkes & Dodson, 1908)

Yerkes-Dodson Law

Hebb's graph of the Yerkes-Dodson Law (image source: wikipedia)

Hebb’s graph of the Yerkes-Dodson Law (image source: wikipedia)

Two things eventually arise from dog training methods that involve prolonged arousal or stress.  First, as cognitive function deteriorates, behavior becomes resistant to extinction.  Thus if our objective is to make a particular behavior diminish or stop, in actuality the stress initially preserves the ineffectual behavior (Schwabe & Wolf, 2011).  As stress continues to move in the “high” range of the graph above, corticosteroids are actively being pumped by the hypothalamo-pituitary-adrenal (HPA) axis to support sympathetic nervous system activity (commonly referred to as “fight or flight”).  When these systems are stimulated excessively—because the physical well-being of an animal is at harm—an animal’s learning for a survival strategy impedes learning of the task/behavior (Joels et al., 2006).  Eventually, as learning and performance come to a halt, a dog enters a state of learned helplessness.

Harsh punishment and the “Hang” – a dog’s fight for survival

In a case study published in the Journal of Veterinary Behavior (Grohmann et al., 2013), a German Shepherd was diagnosed with severe cerebral edema resulting in ischemic brain damage from a training session with its owner.  When the dog failed to perform desirably, the owner “disciplined” the dog by hanging it on its leash with an equipped choke chain for 60s.  Brain ischemia, or cerebral ischemia, is caused when there is a lack of oxygen rich blood flow to the brain causing cerebral hypoxia and brain death—in layman’s terms: death or brain damage by strangulation.  Other presenting conditions included:

  • Anxiety
  • Panting
  • Tachycardic (racing heart beat)
  • Severe disorientation
  • Pleurothotonus (abnormal and sustained involuntary muscle contractions)
  • Blindness
  • Bilateral mydriasis
  • Left-sided facial motor paralysis

Medical differentials for the presenting conditions included diffuse axonal injury, vascular ischemia, increase in intracranial pressure, and hemorrhage.  The dog was euthanized after the diagnosis was made and the owner declined a postmortem examination.

All I can think about when I read stories like this is: what was going through the mind of that poor dog, an emotional and sentient being, as the choke chain cut off blood and oxygen to the brain?

What is dog training

Dog training is literally the act of teaching a dog to perform a certain task—whether it is a sit or to stop lunging on leash—a task which ultimately requires the dog to make a successful decision.  This is a complex physiological process that involves 3 things: the cognitive processing of relevant information, the estimation of relationships between actions and their potential consequences, and use of executive functions to optimize decision-making performance (Mair et al., 2011).

Prolonged and severe stress has deleterious effects on cognitive function, memory formation, and performance (McEwen & Sapolsky, 1995; Yerkes & Dodson, 1908)

Owners and trainers need to abandon confrontational methods and techniques, teach dogs ‘English as a Second Language’, talk to them like a loving parent, learn their cognitive landscape by playing and interacting with them, and enjoy the fact that they are not a robot: they are an individual with complex biological emotions and thoughts.

References:

Grohmann, K., Dickomeit, M. J., Schmidt, M. J., & Kramer, M. (2013). Severe brain damage after punitive training technique with a choke chain collar in a German shepherd dog. Journal of Veterinary Behavior: Clinical Applications and Research. doi:10.1016/j.jveb.2013.01.002

Joëls, M., Pu, Z., Wiegert, O., Oitzl, M. S., & Krugers, H. J. (2006). Learning under stress: how does it work? Trends in Cognitive Sciences, 10(4), 152–158. doi:10.1016/j.tics.2006.02.002

Mair, R. G., Onos, K. D., & Hembrook, J. R. (2011). Cognitive Activation by Central Thalamic Stimulation: The Yerkes-Dodson Law Revisited. Dose-Response, 9(3), 313–331. doi:10.2203/dose-response.10-017.Mair

McEwen, B. S., & Sapolsky, R. M. (1995). Stress and cognitive function. Current opinion in neurobiology, 5(2), 205–216.

Schwabe, L., & Wolf, O. T. (2011). Stress increases behavioral resistance to extinction. Psychoneuroendocrinology, 36(9), 1287–1293. doi:10.1016/j.psyneuen.2011.02.002

Yerkes, R., & Dodson, J. (1908). The relation of strength of stimulus to rapidity of habit-formation. Journal of Comparative Neurology and Psychology, 18, 459–482.

Canis lupus familiaris

Ray and Lorna Coppinger said it most succinctly:

“Behavior is the functional component of evolutionary change.  How well an animal runs is the selective force, not its legs.  Paleontologists study the evolution of hard parts because those are what fossilize.  Studying changes in femur lengths, however, leads to the misconception that it is legs that evolved, rather than running or jumping.  For biologists, the evolution of dog behavior is found in the mechanisms of evolutionary change from the antecedent wolf behavior.”  (Coppinger & Coppinger, 1996)

The biggest pitfall when viewing dog behavior from an evolutionary perspective is when people confuse the words of authors like Ray and Lorna Coppinger and claim that ‘because the dog is a descendant of the wolf, giving our dogs a wolf way of life is what they understand best’.  The first problem is that behavior is phenomenally more complex than simply the order in which genes make proteins.  The subject of behavioral genetics in lay discussion often conceptualizes genetics holding its animal host hostage by allelic gunpoint to bend to its will.  It did not help that for a while, science was still trying to understand the question of ‘nature vs nurture’ and everyone had an interpretation.  We know today that it is neither and it is both–the development of an organism comes down to the interaction of genetic activity, neural activity, behavior and environment (Gottlieb, 1991).

"A simplified scheme of the developmental systems view showing a hierarchy of four mutually interacting components in which there are "top-down" as well as "bottom-up" bidirectional influences." (from Gottlieb, 1991)

“A simplified scheme of the developmental systems view showing a hierarchy of four mutually interacting components in which there are “top-down” as well as “bottom-up” bidirectional influences.” (from Gottlieb, 1991)

The second problem is that the wolves we observe today are not the wolves that our dogs evolved from–they too are also evolutionary decedents.  While many well-respected authors have proposed that domestication occurred somewhere from 30,000 to 135,000 years ago (Vila et al., 1997), other well-respected authors argue instead it was likely somewhere between 8,000 to 10,000 years ago, and the matter is hardly settled (Larson et al., 2012).  Regardless of the exact date, since the domestication of the dog, humans have reduced the estimated worldwide wolf population from over 2 million to less than 200,000.  Not only do the wolves today make up a slim 10% of the population that our dogs evolved from, but our dogs have grown into a worldwide estimated population of 500 million—undergoing genetic selection with each generation.  When given the immense differences in ecological requirements, it would almost defy the theory of evolution–the most empirically supported theory in existence (Coyne, 2009)–if there were no variations.  The tendency to make grand generalizations about the behavior of dogs and wolves is extremely problematic at best and a tremendous amount of care should be taken whenever one does.  Discussing animal behavior from an evolutionary perspective is therefore not akin to saying these two sub-species of Canis lupus–grey wolves (Canis lupus lupus) and dogs (Canis lupus familiaris)–are evolutionary reflections of each other.  Animals evolve to adapt to their ecological niche, and for the dog, that niche is our farms, our cities, our streets, our garbage dumps, and most importantly our homes.

References:
Coppinger, R., & Coppinger, L.  Biological Bases of Behavior of Domestic Dog Breeds. 1996, V. L. Voith and P. L. Borchelt, Eds., Readings in Companion Animal Behavior, Veterinary Learning Systems, Trenton, NJ. pp 9-18.

Coyne, J. A. (2009). Why Evolution is True. Penguin.

Gottlieb, G. (1991). Experiential canalization of behavioral development: Theory. Developmental Psychology, 27(1), 4–13. doi:10.1037/0012-1649.27.1.4

Larson, G., Karlsson, E. K., Perri, A., Webster, M. T., Ho, S. Y. W., Peters, J., … Lindblad-Toh, K. (2012). Rethinking dog domestication by integrating genetics, archeology, and biogeography. Proceedings of the National Academy of Sciences, 109(23), 8878–8883. doi:10.1073/pnas.1203005109

Vilà, C., Savolainen, P., Maldonado, J. E., Amorim, I. R., Rice, J. E., Honeycutt, R. L., … Wayne, R. K. (1997). Multiple and Ancient Origins of the Domestic Dog. Science, 276(5319), 1687–1689. doi:10.1126/science.276.5319.1687