Human races are not like dog breeds

If you googled for information comparing race in humans to dog breeds, we wrote this open access, peer-reviewed article specifically for you. There is even a glossary at the end of the main text, and some of the sources we cite are also open access. Thanks for reading.

Human Races Are Not Like Dog Breeds: Refuting a Racist Analogy

https://evolution-outreach.biomedcentral.com/articles/10.1186/s12052-019-0109-y

Are human races like dog breeds? No.

Are human races the same as dog breeds? No.

Are human races just like dog breeds? No.

Are human races basically dog breeds? No.

 

Such a good boy, Elroy

We lost a beloved friend yesterday. Our dog Elroy. He made many appearances on The Mermaid's Tale over the years, and he even visited a few classrooms, both in fur-person and via the lesson plan he helped create for Berkeley's Understanding Science website. But far beyond all he inspired, he was just pure goodness and we're grateful to have been loved by him and to have loved him in return. Such a delightful, clever, and utterly adorable friend will live with us forever.

Such a Good Boy, Elroy

He never stole a thing. Not from us, not from Murphy. We could leave a cheeseburger on our plate and leave the room and it’d be there when we returned.

Murphy was the sneaky one, the dog’s dog. Not Elroy. We thought he was so smart. To obey our rules while we were gone! Little did we realize until many years later that he just had a different dog’s strategy. Just take the food while we're looking, willing. Sometimes right out of our hands, sometimes right off our plates, sometimes right out of our mouths, even.

He never stole a thing, until today. Today he stole a whole day of living. He’d be dead already if Dr. Roy hadn’t taken today off.

Instead of dying, Elroy hung out with me. Mostly I lorded, and we quarreled some. He wanted to chew off his toes. I didn’t want him to chew off his toes. I refitted him with a tube sock each time he gently slid it off with his teeth. I’d get up to get a snack and by the time I was back, the sock would be off, blood would be spilled, I’d put on a new sock, and sit with my hand on his paw until he stopped nipping at the sock, panting, waiting.

Wearing just this one white sock, he’s suddenly naked.

And it’s like this, after hours of morning tube sock standoffs, that he and I are lounging this afternoon under the mulberry tree in the backyard. Not at all what we could have done if Dr. Roy hadn’t taken the day off to do whatever it is that he had to do today instead of be in his office to take our meek, phlegmy phone call this morning.

And this place? Back in the far corner near the compost pile and the bucket we use to collect dog turds? Yes. This place.

We're nestled down with five bare feet under the shade of this mulberry tree, pressed up against the grasses that grew purple irises in May, in this spot, in the berried dirt, that he chose, and he’s forgotten all about his tumor and his toes. 

We’re letting spiders crawl all over our skin and fur, and licking the blood that had splattered onto his good leg, and sniffing the blood that just squashed onto my fingers when I smashed a mosquito, and panting and drooling, and interpreting the crows perched in the tops of the pines, and humming with the lawnmower across the street, and smelling, through the snot that’s filled my face for days, the gentle gusts that rustle the tall grasses and the leaves and that push the mulberried branches and the puff clouds northwards up in the sky.

We spot our first hummingbird. We watch a bee chase a sparrow while Murphy herds the cars that travel the lane that circles our yard.

And I worry whether this fetus can tell that I’ve been crying so hard and for so long and whether doing this to him, on the heels of that electric Beck concert on Saturday night, is good parenting. He’ll never get to grab a chubby little handful of Elroy’s neck fur.

And I can’t get the needle to jump past, “These are the wo-oooords we use to say good-by-yyyyyyyye.”

And I’m reminded of another time I sat for hours with another kind of orange beast, fascinating her with the contents of my luggage, unpacked and repacked, over and over and over again.

And I wonder whether this vantage, under the mulberry tree, is where my lovely orange friend would like to be buried. And I start to cry again. So I stroke his cashmere ear some more.

And I think I’m sitting here for Elroy, but I know he’s sitting here for me.

Elroy Beefstu Stacey (2003-2014)

The Mismeasure of Dog

When you see a study that claims to predict behavior variation with cranial variation your anthropology radar might start pinging. If your anthropology radar's especially sensitive, it will ping regardless of the organism. And when that organism is the domestic dog, you might be tempted to ready the torpedoes before you've even read the abstract.

That's because, for one, people often like to compare human races to dog breeds. Conversations rooted in eugenics or racism often involve judgments of blood purity, much as American Kennel Club members and Westminster Dog Show contestants owe their worthiness to their pure bred ancestors. This isn't a perspective that many anthropologists abide.

And, secondly, there's a long history of measuring human heads, divvying them up by race, showing that they're distinct by race, and then explaining differences in behavior at the race-level in the general or specific context of those race-level differences in the head. Another practice that few anthropologists abide.

We're going to cover some ground on human heads before getting to the dogs'. So please... Sit... Stay... And if you do, we'll get to the dogs in just a second.

Brain size, or cranial capacity, has long been a favorite measure by folks interested in human variation. The cephalic index (CI) has too. These have been used in the name of science by racists, racialists, and folks who are neither. CI might be a favorite because not only does it appear to separate race categories and even populations within them, but it's easily, cheaply, and noninvasively obtained from live humans, while it also avoids phrenological subjectivity.

How phrenology-free is CI? It's not completely clear because, to my knowledge, no one has linked CI to behavior any better than they can with a lumpy left parietal. Remember, however, that many CI uses have not, and are not, for explaining behavior. CI's often measured to study human variation between or within populations, and maybe relatedness, and maybe change over time (evolution).

In anthropology, CI involves the ratio of the breadth to the length of the cranium.

Superior view of a human cranium. Red lines show the two parts of the cephalic index (CI = breadth/length x 100). (photo source)

People even created terms for different CIs: wide, broad skulls are brachycephalic and narrow, long ones are dolicocephalic. CI is influenced greatly by genes (accumulated in ancestry through any number of evolutionary mechanisms). The trait is complex and polygenic, sharing genes that affect other traits. For example, stature is linked to skull length: the taller a person the more dolicocephalic they might be. Environment also contributes to a person's CI which might explain apparent changes at the population-level seen between parents and offspring:

Depicting Franz Boas's CI data collected from 13,000 European-born immigrants and their American-born children in the New York area. (Figure 10.12 from Human Variation: Races, Types, and Ethnic Groups, 6th ed. by Stephen Molnar)

Notice how the changes in the American born children weren't all the same sort of change. That's probably one of the reasons that Corey Sparks and Richard Jantz wrote, "A reassessment of human cranial plasticity: Boas revisited." Boas's big classic dataset had long been used to demonstrate the strength of environmental effects on cranial variation. But with Sparks and Jantz's new consideration of the data, it looks like foreign born and American born people with similar ancestry have more similar head shapes to one another than foreign born compared to American born, regardless of ancestry.

Figure 1 from Sparks and Jantz (2002)

Sparks and Jantz make this point by extending the comparison:

"In America, both Blacks and Whites have experienced significant change in cranial morphology over the past 150 years but have not converged to a common morphology as might be expected if  environmental plasticity plays a major role (29).

We send out our genes wherever our genes may go and that includes, apparently, how our offsprings' adult heads will be shaped, roughly, regardless of where their heads live.

In conclusion, Sparks and Jantz discuss the context a hundred years ago:

"We also must consider the attitude of Boas toward the scientific racism of the day. Evidence of Boas’ disdain for the often typological and racist ideas in anthropology have been reviewed previously (45) and are evident also in his later publications (46–48). Boas’ motives for the immigrant study could have been entwined in his view that the racist and typological nature of early anthropology should end, and his argument for dramatic changes in head form would provide evidence sufficient to cull the typological thinking. We make no claim that Boas made deceptive or ill-contrived conclusions. In
Fig. 1 it is evident that there are differences between American and European-born samples. What we do claim is that when his data are subjected to a modern analysis, they do not support his statements about environmental influence on cranial form."

Acknowledging the strong possibility that genes are more powerful determinants of head shape than environment isn't offensive to many of us today, even those of us who are sensitive about these sorts of data because of their past uses or their potential for future abuses.

But maybe the environment affects different head shape genotypes differently? Why assume that similar environment will result in similar phenotypes if the underlying genotypes are different to start? Isn't the change in phenotype enough to show environment matters enough to consider it important? Perhaps Boas's data aren't sufficient for answering these questions.

And maybe humans just don't have very varied head shapes in the grand scheme of things, in the big picture of whatever "variation" is, and our perception of such typological differences is just what we're good at doing with things like human heads.

But humans and our variation and how we explain and perceive it aren't the main reason we're here today! 

I've introduced human CI, human cranial shape variation in general, and the history of typological race studies linking human head shape and human behavior, because...


One of the main findings of a paper recently published in PLOS ONE is that CI predicts some dog behavior:

link to article

[Now do you see what I meant by my opening paragraph? If not, there's a whole literature out there. Brace's Race is a Four-Letter Word is where you might start.]

For brevity, we're going to ignore the height and weight stuff in this paper and stick to the skull shape parts. But I recommend reading the paper for yourself.

The authors cite some papers to establish that skull shape might be linked to behavior.

One "noted that the morphology of working dogs' heads clustered according to their breed's original purpose. This observation was later supported by a series of studies focused on cephalic index."

"CI is correlated with a tendency for retinal ganglion cells to be concentrated in a form of an area centralis rather than a visual streak. This feature of short-skulled dogs means that they have more visual acuity in the centre of their visual field but less in the periphery."

And this is hypothesized to be linked to their being,

"more likely to follow a human pointing gesture, suggesting that the arrangement of retinal cell may link with aspects of canine social cognition."

Also, they cite a study of dog brain MRIs, linking skull shapes (particularly CI) to,

"progressive pitching of the brains, as well as with a downwards shift in the position of the olfactory lobe." 

This established their premise that differences in head shape reflect differences in brain organization and that,

"CI may be associated with changes in the way dogs perceive stimuli and possibly process information."

It's hard to write this through my insane jealousy, but they traveled to dog shows to collect their metric data. Photographs of the superior view of dogs' heads were taken and then used to measure CI.

They stuck to pure bred animals. Then they looked at a dog behavior survey called C-BARQ to see if CI predicted anything in the same breeds there. The survey's owner-reported, but of course, the author's explicitly acknowledge this source of bias that they can't do anything about (except not use it for science).

And lo and behold, CI predicts a few things:

Self-grooming, chasing, dog-directed aggression, allo-grooming, stranger-directed fear, persistent barking, compulsive staring, stealing food. 

All aren't exactly the kinds of behaviors that have been used to describe human races and populations, but some are.

Anyway, that's not what I really want to talk about. I want to talk about CI and its use for predicting behavior.

Here's how they measured it in the dogs:

Dog CI: "The length was measured from the fingertip to the tip of the nose, and the width was measured from each zygomatic arch, which was displayed by the tape placed around the widest part of the dog's head." (Figure 1 from McGreevy et al., 2014 with my blue lines added)

That's fine as a measure of something like the head. What're you gonna do otherwise at a dog show?

But how's that getting at brain shape? Remember, if the behavior's at all going to be about inbred biology as the premise of the paper sets us up to ask...

That is, if the behavior's not due to conditioning based on how the animal looks to humans and other environmental factors influencing behavioral development which are rightly acknowledged in the paper...

And if changes in behavior during life don't matter (which I don't believe are acknowledged in the paper but is obvious to anyone who's lived with a dog)...

Then we've got to be getting somehow at genes or brain shape or something with CI in order to use it to predict behavior.

But look at what their CI measures:

Boxer cranium with anthropology's CI (left; compare to human at top of post) and with McGreevy et al.'s CI (right). photo source 

Anthropology's CI gets at brain shape much better than McGreevy et al.'s. In fact, their measure isn't getting at brain shape any more than it's getting at meat helmet thickness (all that space between the zygomatic arches and the braincase) and snout length.

With this metric, the paper could be entirely rewritten to discuss not brain shape but meat helmet size as a predictor of behaviors instead.

There are many ways to take this discussion beyond merely pointing out that this measure of brain shape isn't. And I'll wrap-up with a few of those here.

First of all. I'm not an expert on the dog literature but it did stick out that they didn't cite a nice paper in American Naturalist from just a couple years ago--"Large-Scale Diversification of Skull Shape in Domestic Dogs: Disparity and Modularity" by Drake and  Klingenberg--that lends some support to their approach to dog head variation, by breed, and whether it's linked to behavioral variation by breed:

"The amount of shape variation among domestic dogs far exceeds that in wild species, and it is comparable to the disparity throughout the Carnivora. Moreover, domestic dogs occupy a range of novel shapes outside the domain of wild carnivorans."

Look at all the morphospace that dogs' heads are taking up! (from Drake and Klingenberg, 2010)

But Drake and Klingenberg's study also discovers and raises some really important issues that were not considered by McGreevy et al in PLOS ONE:

"The disparity among companion dogs substantially exceeds that of other classes of breeds, suggesting that relaxed functional demands facilitated diversification. Much of the diversity of dog skull shapes stems from variation between short and elongate skulls and from modularity of the face versus that of the neurocranium. These patterns of integration and modularity apply to variation among individuals and breeds, but they also apply to fluctuating asymmetry, indicating they have a shared developmental basis. These patterns of variation are also found for the wolf and across the Carnivora, suggesting that they existed before the domestication of dogs and are not a result of selective breeding."

So we're left wondering why this paper didn't even attempt to deal with genetics and development, that is, the phylogeny of dog breeds. If head shapes vary according to phylogeny, but within those clusters we see variation in behavior, then there's not such a strong link.

I think that phylogeny's ignored because it's not yet worked out. I just went back into the paper and found they do at least bring it up: "A cluster-based analysis of full genomes of these different breeeds may prove helpful in this domain."

It doesn't look like we're very far in dog breed phylogenetics according to (one of my oft go-to pieces for teaching examples of "simple" genetics) Parker, Shearin and Ostrander's review of dog genetics.

"An unsupervised cluster analysis of dogs and wolves. Using clustering algorithms with more than 43,000 single-nucleotide polymorphisms (SNPs), 85 dogs, representing 85 different breeds, along with 43 wolves from Europe and Asia, were assigned to 2–5 populations (inner circle to outer circle, respectively) based solely on genomic content. Each column represents a single individual divided into colors representing genomic populations. Blue indicates a wolf-specific signature, and red indicates a dog-specific signature. Note that the majority of crossover lies between ancient dog breeds and Chinese or Middle Eastern wolves. Figure originally published in Nature (158)." (Figure 1 from Parker et al., 2010)

That's not resolved well enough to be useful for McGreevy et al. (But I could be behind the times.). And granted, the figure I pasted there is aimed at seeing which dogs are most primitive or most like wolves and, maybe then, most like the earliest dogs. But domestic dog breed relatedness must be better worked out than this, given the things Wisdom Panel (using Ostrander's dog breed markers!) can do to pinpoint the breed ancestry of mutts like my pals Elroy and Murphy. (And here's where I learned from the horse's mouth what this test does.)

It does make one wonder, though, whether the dogs that have more wolf-like heads behave more like wolves. That kind of evidence would go a long way to support interest in linking domestic breed heads to their non-wolf-like behavior. But it's not in McGreevy's paper as far as I can tell.

But again, if you've got sensitive anthropoogy radar, it's pinging. First of all, isn't asking about which dogs are most like wolves the same as asking which humans are the most like chimps? Uh, no. But, yeah, kind of. And I'm in no state of mind to expound on that one here today given the trolled-up comment thread that would surely ensue.

But, second, it's troublesome that papers with easy measures and hypothetical (at best) or false (at worst) correlations between anatomy and behavior are published so far in advance of the best sort of data to answer their questions (e.g. a fully resolved phylogeny, let alone mapped genes for the brain shape or the genes for the behavior, etc etc...).

A deterministic and scientifically impatient (to be kind) approach to variation is what still haunts us about the history of physical anthropology. And to see it potentially playing out in other organisms like dogs need not raise any of our politically correct hackles, but I hope it arouses our scientifically critical ones.

Whooza good gurrrrrl? Whoozmai bayyyy-bee boy?

I think we should stop feeling sheepish about treating our dogs like kids. After all, blurring the line between dogs and people is not exactly new to just the sickos of our modern world.

One of these sickos with @ElroyBeefstu

Many cultures, across space and time, made wolves and dogs the stars of their origin myths. Their human origin myths. Canids weren't just nursing the infant founders of Rome, they were actually part of some peoples' conception too. [For more check out a great read by Marion Schwartz.]

Sure, sometimes the same people that lifted dogs up chowed down on them too. Long the fate of Chow Chows, dog meat's been a big hit on myriad ancient menus. We could even make the case that Paleo Dieters should put Spot on a spit. [Aside: Paleo Dieters should also try second harvest if they're earnest, but that's even less likely to catch on than literal hot dogs.]

Anyhow, this dog-crazed world that's gone to the dogs, head over heels for the dogs, didn't just poof out of the blue.

Without a legacy of dog obsession we wouldn't have them as they are now. Even if the first tens of thousands of years of their domestication was mostly unintentional, our enduring relationship with dogs was a natural precursor to this:

source

Evolving right alongside the pop culture popularity of dogs is the flourishing scientific interest in them. Part of that has to do with the simple fact that they're built to cooperate with human experimenters, like with this dog swimming study going swimmingly. And this reminds me of a story I read a while ago (not here but this is where I relocated it) in which a dog that's so eager to please lifts her paw to shake with the human carting her off to be vivisected.

Aw. Sorry. Let's pause and shake out those bad thoughts....

source, with so many more

OK. Much better.

It's thanks to the enthusiastic dissemination of the increasing amount of dog research that, for example, I could learn about the dog visual spectrum when I was curious and googled for it:

Source and here too. 

See? All those red chew toys for Rover are much more visually appetizing to the primates who purchase them.

Also, not too long ago, I learned via Twitter...

"defecation (1,893 observations) & urination (5,582 observations)" in dogs: evidence for magnetic field sensitivity http://t.co/cqf1y2KlA6 …
— John R. Hutchinson (@JohnRHutchinson) January 1, 2014

... that when the magnetic fields aren't obscured by clouds, pooping dogs seem to align with the north and south poles. Creates a great opportunity to use "polar vortex" on a daily basis.

It's the behavioral studies that seem to get so much play in the media, especially the cognitive ones and the ones that speak to our relationship with dogs. And I'm a sucker for all those but I'm an even bigger sucker for the evolutionary ones. The ones that do all that but also try to help tell our co-evolutionary tale.

And one of these that really sucked me in is, "Paedomorphic Facial Expressions Give Dogs a Selective Advantage" by Waller et al.

It's such a well-written piece and so simple... too simple, perhaps, but they acknowledge it well and they don't overstate their findings.

The group of researchers wanted to know whether dogs make faces* that are more or less attractive to humans. They were particularly interested in any facial expressions that might enhance the already paedomorphic faces of many dogs--a trait traditionally blamed on selection for cuteness and selection against aggression that's supposedly genetically linked to dog face, head, and ear morphology.

They developed a tool to objectively observe doggie facial musculature changes on film, based on one already in use for humans (FACS --> DogFACS). To collect the data on their dog sample, they stood fairly neutrally outside each enclosure at an adoption shelter and filmed each animal under these conditions for two minutes. To minimize the confounding effects of vastly different dog breed craniofacial morphology, they stuck to one group: the bulls and bull mixes. This was probably also the breed group with the biggest sample size at the shelter. Just a hunch.

Then, they waited to see how long these dogs had to wait to get adopted. That was the measure of human preference or "selection." It's not perfect; one could think of many things that could factor into the time a dog stays in a shelter. But the authors make a strong case for how this is as close to a proxy for selection in our co-evolutionary history as we might get as humans interested in reconstructing that history. We're talking about all that history where we weren't actively breeding short-legged corgis, but instead just co-existing with dogs.

Lip pucker, lip corner puller, nose wrinkler, eye closure, blink, mouth stretch, jaw drop: These are some of the expressions they captured but none so much as the inner brow raiser. It's the face you make when you flex your medial frontalis and that a dog makes when flexing its levator anguli occuli medialis. This trait was the focus of the paper. The authors say that by raising the inner brow, a dog's eyes appear larger which is more puppylike, more paedomorphic. This simple maneuver also reveals their white sclera--tissue that's long been assumed an important signal for non-verbal communication among our kind.

Elroy's doing it more, but we're both raising our inner brows and showing our sclera.
Therefore, you want to adopt us. 

The code for inner brow raise is AU101 and here's how the data per dog plot out.  X-axis shows AU101 frequency during filming and y-axis is the length of time on the adoption market.

Figure 2 from Waller et al.
"Relationship between frequency of AU101 and days before re-homing in the dog shelter.
Curved line shows the power estimation."

A quick glance shows an apparent pattern in which dogs that make this facial expression more frequently are adopted faster. And that could be the case, but with this small sample it's not a strong case. If we remove only those five dogs in the blue circle that I slapped on there, it's not much of a relationship at all. Still, the paper acknowledges this in so many ways and the whole paper just makes so much sense I can't even be mad about the sample size.

You might not be mad either if you ever adopted a dog from a shelter or if this passage from the end of the article speaks to you:

In humans, the equivalent facial movement to AU101 is AU1(inner brow raiser), which features heavily in human sadness expressions [20]. It is possible, therefore, that human adopters were responding not to paedomorphism, but instead to perceived sadness in the dogs looking for adoption.

Guilty as charged. This is the sad, pensive face I saw standing behind the bars at the shelter. All the other dogs were hurling themselves towards me and this little girl stood back and did this:

My sweet sad-faced Murphy.

Sure I could have been homing in on her paedomorphic expression and only overlaid my perception of her sad, thoughtful nature which was also so appealing, but they could be all part of the same phenomenon.

Here's the rest of that paragraph from the paper, to round out the discussion about other explanations besides a preference for straight-up cuteness or paedomorphy with this facial expression:

However, it is also possible that the human sadness expression is itself derived from paedomorphism, and that sadness is attributed to this specific facial movement because it enhances paedomorphism and thus perceived vulnerability. Another possibility is that humans are responding to the increase in white sclera exposed in the dogs as the orbital cavity is stretched through AU101 action. Visibile sclera is a largely unique human trait [27] (which likely contributes to our extensive gaze following abilities) and people are more likely to cooperate or behave altruistically when exposed to cues of being watched [28], [29]. It is unclear, however, whether it is the sclera specifically or simply the presence of eyes per se which has such a powerful affect on human behavior and attention, and so this is more a complimentary hypotheses as opposed to an alternative.

So her white sclera guilted me into taking her home. Maybe that's what it was. The Eckleberg Effect.

Something tells me I'm using this symbol wrong here. But forgive me, I didn't read this with a teacher to tell me how to interpret it.

Whatever it is, it worked then and she still looks like this and it still works on me. 

In closing, I'm wondering whether these expressions are simple and genetic, or are enhanced by positive conditioning during life. It's unclear from this paper, but that's a whole other paper (or career). I wish this paper included a survey with the study, asking the humans who adopted these particular dogs, Why? And, of course, the tiny elephant in the room is that all these dogs were taken home by somebody eventually... so is this as good a proxy for selection over evolutionary time as we're tempted to think it is? I'm not sure. I haven't let this sit with me for long enough and clearly I'm way too excited about how it explains my own adoption story, with Murphy, at least with so many related options. I feel psychoanalyzed. It's thrilling! I'm just glad I wasn't asked to review this paper. What a conflict of interest!

On a final note. It's often said that humans are self-domesticated, or just plain domesticated, animals. And within that discussion we talk about how we're cute and have especially cute babies because we preferred them and cared for them and hence they were able to survive and replicate their cuteness. But doing that to dogs, which are without a doubt domesticated, is a bit different from doing that to ourselves don't you think? 

Taking credit for dog cuteness--be it their facial expressions or the way their structures scream squeeee! when they're puppies and into adulthood--seems not unreasonable given what we've  untinentionally and then intentionally done to dogs recently, happily encouraging breeding in some and snippily discouraging breeding in others. 

But to take credit for our own cuteness the way some of the just-so stories answer 'why are babies cute'... that's a little harder for me to fathom. Instead the best explanation for why babies are cute seems to be not that they are inherently so, but that our perceptions of their cuteness are inherently so. If we didn't behold them as adorable, lovable little creatures, we might be in trouble given how long they depend on us before they make cute little adorable creatures for themselves. And it's these perceptions that we can redirect as preferences onto other creatures, spreading our love all over the wild kingdom, but mainly, for now, all over dogs.

source

source

*If you misread "dogs make faeces" here you're not alone. That dog-poop-polar-alignment story really sticks!**

** If you read that as "really stinks!" then you and I need to find the same shrink.

My dogs' evolutionary history. Part 3: Inside scoop and why

Recall that we ordered DNA testing kits for our mutts. First we made predictions, then we revealed the results. Today I want to tell a bit more of the story...

yawn

Remember that time a doctor used a vibrator on my hips because I had a cyst on my knee? I was all into it "for science." It was an opportunistic science sting operation. There was totally gum on my shoe. There was all kinds of pseudoscience that day.

Anyway, I was all psyched up for that sort of Dateline-style, hidden camera intrigue when I called up Mars Veterinary, the people who do the analysis for Wisdom Panel doggie DNA kits, last Friday afternoon. I was all psyched up because, as Kevin said, I needed, "to make sure they're not defrauding people."

Me? I do? Little old me?

That sounds about right. I mean, just because I can see all the educational potential here doesn't mean I should be endorsing it without understanding it better. And while I'm understanding it better shouldn't I make sure they're not entirely full of s--t?

But I already know they're not full of s--t because they gave us results for both Elroy and Murphy that made sense. They didn't report crazy results and there are lots of ways they could have... there are 200 breeds on that list, most of which do not look like our dogs or like they've wafted their DNA anywhere near our dogs.

So, they can't be completely fraudulent. Whew. Okay then, less of a burden on me for this interview. But wait. Could it be maybe a little more nuanced, this hypothetical fleecing? After all, they're the ones who saw my blog and reached out to me to have an interview--isn't that a little big brothery? And, after all, their website doesn't tell us what their methods are, not really, not for those of us who have ever operated a PCR machine or run a gel. And they don't tell us what these markers are in our dogs' reports that led them to make the reports. I'm used to having too much information, even, because of 23andMe.

Anyway, there were all kinds of reasons to be professional when I called up the veterinary geneticist. But after she answered my first question so well, I pretty much lost all professionalism and drooled all over her, albeit through the phone.

Here's what I learned. Please bear with me... I didn't take direct quotes because (a) that's hard to do without a hands-free headset (or fancy recording software I don't have because I never needed), and (b) I got a wee bit excited and flailed my arms most of the conversation. 

All questions and answers are my paraphrasing.

Question: Are you using a chip or what? How are you genotyping?

Answer: A chip like 23andMe's isn't cost effective. Yes, there's a chip but it's not specific to the test. They use a sequenom platform. It's PCR markers combined into panels.  They run those PCRs for 321 markers, broken up into several panels, optimized so that they don't interfere with each other clearly and don't have to change primers. They use nested PCR for segmenting around the mutation and then to get the exact SNP they throw the DNA in a mass spec to find the particular A, T, C or G mutation. Each has a different weight, so each can be identified. 

Question: Do you get both alleles from that?

Answer: Yes. They don’t sequence in both directions but they sequence both chromosomes.

Question:  Are those 321 markers for visible or perceptible phenotypes? 

Answer: No. None are visible phenotype. They're ancestry markers/SNPs.

Question:  Have you found any dogs that have none, not one, of those breed markers?

Answer: No. And we don't expect to. But it's not completely out of the question given the spectral nature of variation over space and time. 

Question: How did you validate your mixed breeds family tree methods? Do you have mixed dogs with known parents and grandparents and type them all in the family?

Answer: The pure breed tests validate so well already. And also, yes, they do validate with mixed dogs with known heritage but not many. The methods are built out of Ostrander's research with 85 breeds, 5 dogs from each and 96 microsatellites. She licensed the patent exclusively to WisdomPanel. 

Question: How do your mixed breed reports compare to how people guess based on external cues? Aren't people already good at guessing their mutts ancestries?
Answer: Actually they're not. Ancestry DNA testing is much better. People aren't that good at guessing mutt ancestry based on phenotype, as far as the few studies suggest. (There's one by Victoria Voith that I want to check out and there's one by Levy on pitbulls specifically.)

***

We chatted for much longer than that and she shared all kinds of interesting information about genetics for dogs' visible traits and also lots about their reproduction which I'm keen to learn about. But that right there's all the relevant information regarding our doggie DNA testing experience that I got during the 30 minute phone call. She was completely open with me about everything which is why I'm kicking myself that I forgot to ask why they require the dog's weight when you submit its cheek swabs. I have a hunch, however, that it's got something to do with validating their mixed breed body size estimates given how many people use WisdomPanel on shelter puppies that will be better adopted if their projected size is known. 

So the question remains... If you don't have a puppy or don't care what it will grow up to look like or be like, why do Wisdom Panel? 

The promotional video on the homepage sums up why many people might do it: 

I wasn’t sure what my dog was made up of...Pretty sure she wasn’t just a [breed name]...I wanted to know so I could tell people when they ask me 'what kind is she?'

This is fascinating.

Why do we care where our dogs come from or what kind they are? Same reason we care the same things about humans and ourselves. And it all boils down to the fundamentals of the field of anthropology... and it's complicated.

And finally, why have I titled all three of these posts "my dogs' evolutionary history"? Because evolutionary history is a synonym for family history and for ancestry. And vice versa, all around. And, clearly, I'm trying to make a point about that.

When you type "evolution" into the Wisdom Panel website search, this is what you get:

But that's not going to stop me from using this to teach evolution. I've decided that Wisdom Panel will be a good alternative for students who aren't interested in doing 23andMe in my anthropology courses, so I'm going for it.

Dogs, humans, what's the difference?  A lot and not.

http://evolutionpsa.tumblr.com/

My dogs' evolutionary history. Part 2: Results

Yesterday we made the predictions of the breed signatures we'd find in our dogs' DNA.

If you didn't already, please consider going back to yesterday's post first before reading today's. Predictions are key! It's best if you confirm our guesses and/or add your own. (...what are the reasons for your predictions? Size? Color? Ears? Tails? Fur? Snout? Furnishings?)

Sadly (yes, sadly), predictions are not part of the official Wisdom Panel or 23andMe experiences. When I teach with 23andMe predicting the results is a major assignment early in the semester. Not only is making predictions the best practice for later scientific evaluation of the results, and it's the best way to force yourself to come to terms with how inheritance and gene expression work (and don't work), but guessing the outcome first makes reading the results orders of magnitude more fun ... not to mention how it makes things a lot less nerve-wracking when it's about your own DNA with 23andMe.

Briefly, before I reveal our dogs' results, let's consider a couple important things first...

Dog breed markers are mutations. 
Just like anything else alive right now, all dog breeds, no matter how "pure" or revered, are mutants. All of their dog traits just like all of our human traits, good and bad, started out as new mutations. Even the ones we all share that contain little variation now (like our genes involved in the development of five fingers and five toes), but also the ones that vary among our populations (like our genes that affect our pigmentation).

And mutations aren't just a population thing; each of us has a tiny fraction of our genome that's mutated compared to our parents. As far as we know, mutations occur in the making of all babies and puppies, etc. Most are neutral, some are bad, some are good.

We're all mutants because mutation, perpetual change generation upon generation within a lineage, is constant. Stasis is not.

This constant change in every puppy is fundamental to why we can have hundreds of dog breeds today.

Many dog breed traits are genetically simple.
Dogs seem to be particularly simple kinds of mutants.

The mutated genes that determine the traits that distinguish one dog breed from another are remarkably few and remarkably simple, but that simplicity makes a lot of sense.

Since humans coaxed these breeds out of ancestral dog stocks and also out of other breeds (as they still do today), it's easy to imagine that new simple traits, not new complex ones, had the best potential to be easily and quickly propagated into future generations and eventually into new breeds.

If a trait arose that was preferred, and it was caused by the kind of genetic mutation that could be simply and somewhat reliably expressed in offspring that inherited it, that mutation and the trait it produced could be increased in future generations by promoting breeding of those new attractive mutant dogs and their offspring.

(source)

If dog breed traits were genetically complex (based on many genes, for example), they would be terribly difficult to produce through controlled breeding of parents with those traits... at all... let alone during one human breeder's lifetime! That's at least partly because there would be far too many puppies without the preferred trait and it would be far too difficult to preserve a trait at an appreciable frequency in a lineage. Of course, inbreeding with very close relatives that share the mutations helps a great deal with this.

Humans have taken advantage of the simple mutations that have popped up in dogs (as they pop up in all living things!), due to sheer feasibility of the breeding outcomes those simple mutations allowed. Like that new coat curl or those new furnishings? Some puppies will have the exact same look. And we're off and running with a new kind of dog...

(source)

I don't know about the genes for Dalmatian spots (and honestly haven't even looked) but I do know about this paper by Cadieu and colleagues from 2009. Apparently you need only three genes (FGF5, RSPO2 and KRT71), each with two alleles (i.e. gene variants; denoted +/- in the figure below) to explain all this coat variation among dogs:

Cadieu et al., 2009

Dog genes are made of the same goop that ours are, and their genomes are very similar to ours because of our shared mammalian ancestry, but they're described as "simple." Evan Ratliff explains some more about why dog genes are simple in "How to Build a Dog:"

The vast mosaic of dog shapes, colors, and sizes is decided largely by changes in a mere handful of gene regions. The difference between the dachshund's diminutive body and the Rottweiler's massive one hangs on the sequence of a single gene. The disparity between the dachshund's stumpy legs—known officially as disproportionate dwarfism, or chondrodysplasia—and a greyhound's sleek ones is determined by another one. The same holds true across every breed and almost every physical trait. In a project called CanMap, a collaboration among Cornell University, UCLA, and the National Institutes of Health, researchers gathered DNA from more than 900 dogs representing 80 breeds, as well as from wild canids such as gray wolves and coyotes. They found that body size, hair length, fur type, nose shape, ear positioning, coat color, and the other traits that together define a breed's appearance are controlled by somewhere in the neighborhood of 50 genetic switches. The difference between floppy and erect ears is determined by a single gene region in canine chromosome 10, or CFA10. The wrinkled skin of a Chinese shar-pei traces to another region, called HAS2. The patch of ridged fur on Rhodesian ridgebacks? That's from a change in CFA18. Flip a few switches, and your dachshund becomes a Doberman, at least in appearance. Flip again, and your Doberman is a Dalmatian. "The story that is emerging," says Robert Wayne, a biologist at UCLA, "is that the diversity in domestic dogs derives from a small genetic tool kit."

So it's this simplicity that allows companies like Wisdom Panel to genetically distinguish breeds and then look for the signatures/markers of those breeds in our dogs' DNA. It's also the recency of most of these breeds (no more than a few to several hundred years at most) that allows us to assume (maybe not rightly but still...) that so much of what genetically identifies a breed today is similar to what the breed was working with all along.

And so... without further ado...

Here are the results of mailing off our dogs' cheek swabs and having 321 markers for 200 breeds analyzed.

For Elroy...
This is his "Breed Ancestry Certificate"

The report notes how Rottweiler and Chow Chow are the only ones with confidence. 

How do they make the pedigree chart? 

What I think they do is estimate what percent of the breed contributes to the dog's ancestry and if it's something like 50%, it's one parent. If it's like 25%, it's one grand-parent and if it's like 12.5%, it's one great-grandparent. Any % less than that is lumped into "mixed breed" ... the details of those are guessed at below.  So those placements on either side of his chart are just best fit in terms of percentage. 

What I'm not sure about is why we must assume that 100% of Elroy's ancestry comes from any breed. But, remember that 100% of the markers in the Wisdom Panel test distinguish breeds. That means, this Breed Ancestry Certificate is missing all the information about Elroy that's not analyzed by Wisdom Panel. 

Non-surprises.
We guessed the breeds that they were confident about! There must be something to this test. Especially since we had seen his litter mates and were told by the adoption agency that he was probably rott/sharpei (and later on we figured he was just as likely chow chow as sharpei). SCIENCE works.

Surprises.
German Shepherd and Collie aren't terribly surprising either. He came from Ohio. Those breeds are abundant enough in the region, are allowed to roam free and probably mated like that too for decades upon decades in those regions. And he's a big boy!

But Westie? Westie is a bit of a head-cocker.

Or is it? Westies had to have had big ancestors, first of all, since they descended from wolf ancestors like all other dogs. But something that distinguishes Westies from other breeds is in Elroy's DNA. That means a relatively recent Westie left a signature in his genome. So was it kamasutra lovemaking between tiny Elroy ancestor and big Elroy ancestor?  Or are we talking about love between mixed breeds and pure breeds and mixed breeds over time? Probably.

Here are their best guesses about what contributed to those "mixed breed" mysteries on his certificate.

Mostly big dogs, some ancient and awesome. The Dogo! (Ugh, don't google it... so many fighting and abuse videos.)

Nothing to really take home from this list because they're far off guesses without even a report of percentage there with the bar graph.

For Murphy...
This is her "breed ancestry certificate"

Akita, German Shepherd and Lab are the only confident ones (as noted in the report). 

And here are the most likely breeds contributing to those "mixed breed" mysteries on her certificate.

Non-surprises.

Shepherd! And Lab is another good one considering friends and relatives see lab in her.
Many of her mix guesses are herders!

Surprises.
Akita? That's phenotypically (and maybe genetically(?) will have to check) close to Husky which is another guess we often hear for her. So this is only a little bit surprising.

French Bulldog? Now that's a real head-cocker.

But again, like with the Westie, it's not noted as "confident" in the report, but on the other hand, why not French Bulldog in her ancestry? It just means this is a marker, like with the Westie, that's not tied to outward appearance/phenotype.*

Not enough information...
I wonder what these markers are then; if Westie and French Bulldog are showing up, why? As the website explains, “Physical features characteristic of certain breeds, such as the flattened face of the English Bulldog or the extremely curled tail of the Pug, seldom survive even the first crossbreeding.”

So these markers for unseen traits are fascinating but not explained in the report.  I'm spoiled rotten by 23andMe that tells you everything, down to the A,T,C, or G you have for your allele for whatever gene. I'm guessing that Wisdom Panel keeps all this under wraps because (a) most consumers don't care to know those details and (b) it's in their best competitive and economic interests to keep their methods to themselves.

What's interesting is how some of the hype about these dog tests is similar to 23andMe: They're "for your health!" But unlike with 23andMe, Wisdom Panel says that you're good just going to your vet and saying "she's got Akita in her blood" when you're dealing with health issues.  While 23andMe advocates that you know each and every SNP.  My health is more important than my dog's I suppose, but what's absolutely not clear is how these two very different approaches (ancestry and family history vs. SNP data) are resulting in different health outcomes.

As you might imagine, there's a lot more to say about the evolutionary and anthropological issues these dog tests raise, so please stay tuned. (Here's part 3.)

Kevin and me and our Westie, Elroy, and our French Bulldog, Murphy.

*Or if it is, it's present in only one recessive copy and would require two copies for the visible trait in the Westie or French Bulldog  to be expressed (added June 14)

My dogs' evolutionary history. Part 1: Predictions

[Click here to skip to Part 2 and Part 3]

You might remember Murphy and Elroy from the time we used science to solve the book-eating mystery. Or the time they figured out evolution. (Still looking for puplisher! [sick]) Or maybe you already know Elroy because you follow him (@ElroyBeefstu) on Twitter.

Elroy (I fit in your phone!)

Murphy (awww)

These are the mutts that inhabit our lives, and we theirs.

It's because of our tremendous love for these dogs but mostly because of our tremendous fascination with evolution that we ordered Wisdom Panel kits for each, for my birthday.

What we do

With Wisdom Panel, the process on the consumer end isn't a whole lot different from 23andMe. You purchase the kits online, they arrive at your house, you activate the kits online, you swab your dogs' mouths, pop the kits back in the mail with the postage-prepaid packaging, and wait for an email with the results.

Wisdom panel needs far less of the contents of a dog's mouth than 23andMe requires. And that's not only because the analysis will be far less extensive, but because dogs' lips and face muscles aren't hooked up for spitting into a test tube.

The turnaround was speedy. We sent in the samples on May 28 and got the results June 6.

At this stage in the process, the only red flag is that they require you to submit your dog's weight during online registration. For the love of science, there should be no phenotypic hints required. I hope they don't use weight to discard or confirm dog breeds for their results report.

What they do
Here's what the FAQ says:

Testing your dog with Wisdom Panel® 2.0 begins when you use the cheek swabs to simply collect a small DNA sample from inside your dog’s cheek and send the swabs into the laboratory. Once your sample is received at our lab it is scanned into our database and assigned to a batch for testing. It then undergoes processing to extract the DNA from your dog’s cells which is examined for the 321 markers that are used in the test. The results for these markers are sent to a computer that evaluated them using a program designed to consider all of the pedigree trees that are possible in the last three generations. The trees considered include a simple pedigree with a single breed (a likely pure-bred dog), two different breeds at the parental level (a first-generation cross), all the way up to a complex tree with eight different great-grandparent breeds allowed. Our computer used information from our extensive breed database to fill these potential pedigrees. For each of the millions of combinations of ancestry trees built and considered, the computer gave each a score representing how well that selected combination of breeds matched to your dog’s data. The pedigree with the overall best score is the one which is selected and provided to you in your dog’s individualized report.

This doesn't really cut it for me. I want to know what the methods are and this is all they provide in answers to "Science Based Questions!" This isn't helping much:

Not only does the computer analyze a dog’s DNA for the breeds and their likely proportions in the dog’s ancestry, but it also models which side of a dog’s ancestry each breed is likely coming from.

I'll just have to assume for now that they use something like a chip (because sequencing is still not thrifty) to identify markers that they've already linked to breeds and then they're applying their probability-based analyses to those markers in our dogs in order to provide an estimate of our dogs' ancestry. And what are those markers?

Wisdom Panel only uses what are called autosomal DNA markers, chromosomes that contain most of the genetic instructions for every canine’s body make up (height, weight, size etc.). There are no markers from either the so-called sex chromosomes (the canine X or Y chromosomes). Mitochondrial DNA, or Y-chromosome DNA testing, is rather different as these parts of the genome are passed on intact from mother to child and father to son respectively, but are therefore only representative of either the female or the male lineage. Autosomal DNA is inherited both from the maternal and paternal lineages equally and constantly shuffled by a process called recombination at each successive generation, and therefore is able to give useful information on the breeds found on both sides of a dog’s lineage.
To find the genetic markers that performed best at distinguishing between breeds, Mars Veterinary™ tested over 4,600 SNPs (single nucleotide polymorphisms or genetic markers, where genetic variation has been found between different dogs), from positions across the whole canine autosomal genome from over 3,200 dogs. To further refine the search, Mars Veterinary determined the best 1,536 genetic variations and ran them against an additional 4,400 dogs from a wide range of breeds. This stage of testing resulted in the selection of the final panel of DNA markers that performed best at distinguishing between breeds, ultimately creating the Wisdom Panel genetic database which presently covers over 200 different breeds.

Predicting our results
Both Elroy and Murphy are mixed breed dogs. Here's the list of breeds they say they can detect.  And here's more from the website:

Wisdom Panel® 2.0 breaks down a dog’s lineage in the form of an ancestry tree.  This allows you to see which breeds are present at a parent, grandparent, or great-grandparent level.  Keep in mind that a parent contributes 50% of their DNA to the puppy while a grandparent contributes about 25% of their DNA on average to the puppy.  It follows that a great-grandparent would contribute approximately 12.5% of their DNA to the puppy on average.
Since each of these different levels can contribute different amount of DNA to the puppy, you can see a variety of influence in the puppy’s physical and behavioral traits.  With a parental breed, you are likely to see some physical and behavioral traits from this breed represented unless some of the genes are recessive (requires two copies of the gene variant to show it).  Examples of recessive traits include longhair in most breeds, a clear yellow or red hair coat, a brown or chocolate hair coat, and prick or upright ear set (e.g. like a German Shepherd Dog).  You may see traits from breeds at the grandparent level and it becomes less likely to see physical and behavioral traits from breeds at the great-grandparent level unless those traits are dominant (requires only one copy of the gene variant to show it).  Examples of dominant traits include shorthair in most breeds, black hair coat, black nose, a drop or down ear set (e.g. like a Beagle), and merle/dapple (e.g. like a Australian Shepherd or Great Dane).

For Elroy (85 lbs)
Our guesses = 50% sharpei or chow chow; 50% rottweiler

Kevin was told he was half sharpei and half rottweiler when he adopted him and all his litter mates were black and looked like rotts. He's got tiny ears and a huge square head and heavy neck relative to his body.

We started to wonder whether he was chow chow instead of sharpei when I checked my best dog reference for another breed with a black tongue.

If he's part chow chow then my envy of his fur is no longer so crazy, since the breed was long made for that... and for dinner too. It makes me chuckle every time I call Elroy's dinnertime, "chow time."

For Murphy (40 lbs)
My guess = 25 % German shepherd; 25 % Border collie; 25 % Hound of some kind; 25% unknown village dog. Kevin's guess = 25% German shepherd; 75% Border Collie

Before her greybeard took over.

Unlike for Elroy, Murphy's behavior came into play for these predictions. Her main occupation is to herd each car that comes down the lane along the edge of our lot. She also stalks squirrels and chases shorebirds. And compared to Elroy, she doesn't have as many breed-specific morphological traits.

Who knows? We could be way off. After all, I just took this Dog Bark Interactive Quiz and failed miserably despite knowing exactly what Elroy and Murphy's vocalizations mean.

Results and analysis, right here, tomorrow...

Dog Eats Book: A domestic application of the scientific method

[July 19, 2013: Now a teacher resource at Understanding Science: http://undsci.berkeley.edu/search/lessonsummary.php?&thisaudience=9-12&resource_id=227] 

We had been on a bike ride to our favorite burger joint and as soon as we opened our apartment door, we knew something was off.

Both dogs—Elroy and Murphy—usually greet us with varying degrees of affection, depending on how sleepy they are and depending on how long we’ve been away.

They express themselves by vocalizing, swishing their tails, jumping up with their forepaws, licking our hands or our faces if we bend down, and sniffing our legs and shoes. But this time, although Elroy was as hyper as ever, Murphy held back, sat down, pressed back her ears pulling her face with them, and hung her head as she stared up at us, weakly wagging the tip of her tail.

She looked guilty.

And her mopey expression was reminiscent of the Great Goose Down Throwdown of 2005 (see photo).

Something was definitely up. So we reluctantly hunted around for evidence of destruction and quickly found it.

The book that Kevin just bought yesterday was naked, the punctured jacket strewn in the corner, the back cover was chewed, and the front cover had two puncture holes. When the jacket is placed back onto the book, the holes line up.

"Who did this?" Yes, we actually asked our dogs, trying not to smile or laugh and accidentally reward anyone.

We decided to get to the bottom of this. Of course we don’t want to punish the guilty party; that’s not effective and we’re not mad. The book’s still readable and even if it wasn’t, it’s just a book. We’re just curious about who shreds magazines, sucks on dish towels, rips twenty dollar bills in half and eats half, etc. when we’re not home and we hope to maybe someday figure out how to stop this behavior. Because we've witnessed Murphy wilt in the presence of Elroy's criminal behavior, we couldn't assume that her emotions were betraying her own crime.

So who dunnit? This chewed up book gave us an opportunity to find out which dog was the perpetrator, at least for this particular caper.

And thanks to the SCIENTIFIC METHOD, we can find out who the culprit is!

Question: Who chewed up Kevin’s book?

Theoretical Orientation - Any biases and a logical, testable, reasonable model(s).

We assume that nothing supernatural is to blame for the maiming of the book. No ghosts or werewolves attacked the book. The book did not bite itself. We exclude the possibility that an intruder broke into our house, terrorized one book on Kevin’s nightstand, touched nothing else, and left without leaving a trace of his/her presence. Since there were two live animals with sharp teeth in the house, we assume either of the two animals are responsible and not an intruding animal with sharp teeth from outside.

Hypotheses - Falsifiable predictions generated from the theory. All possible, testable answers to our question.

Hypothesis 1: We cannot say whether it was Murphy or Elroy who destroyed the book.

Hypothesis 2: Elroy did it.

Hypothesis 3: Murphy did it.

Operationalized Hypotheses - The “recipe” that describes measurement, experiment, observation and how another could replicate the process.

Materials: A measuring device (ruler), the book, Elroy's teeth, Murphy's teeth.

Methods: Measure the distance between the upper and lower canines on both Elroy and Murphy. Measure the distance between the puncture holes on the book.

Hypothesis 1: None of the dog tooth measures match the puncture hole measure. (We cannot say whether it was Murphy or Elroy who destroyed the book.)

Hypothesis 2: The distance between Elroy's upper or lower canines is the same as the distance between the puncture holes in the book. (Elroy did it.)

Hypothesis 3: The distance between Murphy's upper or lower canines is the same as the distance between the puncture holes in the book. (Murphy did it.)

Data Collection - In the laboratory, field, library, kitchen, …

Results:

Elroy upper canine distance - 4.5 cm

Elroy lower canine distance - 4 cm

Murphy upper canine distance - 3.8 cm

Murphy lower canine distance - 3.5 cm

Distance between puncture holes in book - 3.5 cm

Conclusions - These should be cautiously limited because they are only based on the above steps.

Hypothesis 3 is supported (and Hypothesis 1 is not) because Murphy's canine-to-canine distance matches the distance between the puncture holes. Hypothesis 2 (Elroy did it) is not supported because canines that are further apart than 3.5 cm could not have made the holes and Elroy's are further apart.

Based on the distance between canines, we conclude that Murphy and not Elroy attacked Kevin’s book.

Further evidence is needed to determine whether Murphy also chewed up the back cover. However, we predict that if that evidence were available it would implicate Murphy as well. But, because our study focused on canine-to-canine distance, we can only conclude that Murphy made the puncture holes on the front cover.

Repeat/Replicate or Revise Theory

To affirm our conclusions we would have multiple measures, repeated by multiple observers, including perhaps a digitized computer observer. We could also recreate the book destruction by offering books to each dog, having them chew them up, and studying the remains. That could verify and distinguish Murphy's destruction patterns from Elroy's. However, we are satisfied with our study and our results and will not continue to further humiliate Murphy. We will apply these data to evaluate any future puncture holes. We could also use this study to launch a new one into the exhibition of guilt and guilty emotions in dogs!

In no way did our study suggest a revision of our theoretical orientation (i.e. natural, domestic causes versus supernatural forces or intruders). However, we cannot claim that our study falsifies the possibility that either supernatural forces or weird intruders had it in for Kevin’s book.

On the other hand, our study and our application of the scientific method deemed those untestable notions unnecessary.

And there you have it. What would we do without the scientific method?

Elroy is thrilled to be exonerated...