Culture: Science & History
Village dogs’ genetic code may hold clues to canine evolution and health
Like classic twin studies that investigate the interplay of nature and nurture, comparing the genome of village dogs to modern dogs may help disentangle the long-term evolutionary effects of genetic and environmental influences.
Mastiff to Min-Pin, Corgi to street cur: all dogs share the same set of roughly 20,000 genes. What makes one dog different from another—or, in the case of purebreds, almost the same— is how the genes are expressed and restricted from being expressed, and how they communicate with one another. Therefore, it may be safe to say that each of the world’s 800 to 900 million dogs is a distinct combination of different versions of the same genes. Or maybe not. At least, that’s what some scientists suspect, and they think they’ll find answers in the DNA of the ubiquitous, free-ranging canine outcasts that populate developing countries throughout the world.
While village dogs were being socially shunned, modern dogs—a subpopulation that likely split off from village dogs thousands of years ago—were serving society. So tightly woven into the fabric of our lives that we rarely think of them as human-engineered, dogs have been refined for increasingly specialized tasks such as hunting, transportation, protection, warfare, ornament and companionship. As a result of rigorous artificial selection over a long period of time, many of their ancestral gene variants are suppressed. Some have disappeared altogether, creating a fragile homozygous genome that has little diversity.
In contrast, village dogs are barely tolerated by society. Although considered a domestic species, they are the products of thousands of years of natural selection. Consequently, their heterozygous genomes are robust and extremely diverse. In addition, it’s possible that long after modern dogs branched off from the family tree, some village dog populations may have developed new gene variants that protect their immune systems.
Evolutionary biologist Adam Boyko, assistant professor in the Department of Biomedical Sciences at the Cornell University College of Veterinary Medicine, is confident that comparing and contrasting the two branches of the domestic canine family tree will provide answers to some of the mysteries that continue to surround the evolution of the domestic dog: When and where were dogs domesticated? What were the global migration paths of humans and dogs? What genetic changes occurred when wolves became dogs? Which genes are responsible for extreme size, shape and behavior differences? What are the underlying causes of genetic diseases? And how do parasites have an impact on canine well-being?
As a postdoctoral student at Cornell, Boyko worked under the tutelage of Carlos Bustamante, now professor of genetics at the Stanford School of Medicine. Curious about how the underappreciated and even less-studied village dog genome might reframe our current understanding of canine evolution and domestication, Boyko and Bustamante persuaded Ryan and Cori Boyko (Boyko’s brother and sister-in-law, who were then both graduate students in anthropology at the University of California, Davis) to add a few side trips to their otherwise romantic African honeymoon. Their instructions were to catch semi-feral, uncooperative village dogs and draw blood samples, then ship the samples back to the lab for analysis. Information from the preliminary DNA samples indicate that the researchers are on the right track. I asked Dr. Boyko about his research, and if it has future application to invigorating the health of our companion dogs.
Jane Brackman: How will mapping the genome of the village dog help us understand the mechanisms of traits in modern dog breeds?
Adam Boyko: Geneticists have spent a lot of time looking at purebred dogs. When something is selected for, either by natural or artificial selection in a population, geneticists can tell because of the patterns that are left in the genomes of individuals in those populations. In humans, for example, we can clearly see that lactase persistence, the ability to digest milk into adulthood, was selected for in some populations.
When we look for these patterns in purebred dogs, we find that things like ear f loppiness and tail curliness are driving these patterns, or short legs or small/big size. Basically, we find the effects of artificial selection by humans for breed standards. If we did a similar scan for selection in village dogs, perhaps some of those same genes would show patterns of selection, but I think we’d also see a new class of genes showing patterns due to natural selection.
For example, maybe there was a lot of selection in early dogs for genes in certain metabolic pathways because there was such an extreme dietary shift from wolves to dogs. Or maybe new parasites and pathogens caused selection at genes influencing the immune system. Or maybe we’ll see selection around genes that influence behavior and temperament.
Basically, there are all sorts of theories about how dogs became domesticated and what makes a dog a dog. When we look at purebred dogs, the main thing we are able to see is what makes certain dog breeds look and behave one way versus another. Maybe by looking at village dogs, which are much less influenced by the strong and recent artificial selection taking place in breed dogs, we’ll be able to see patterns of selection that occurred earlier in dog history.
JB: Might your findings have application for the future? For example, if you were to come across genes influencing the immune system, would breeders be able to use that information to revitalize the pedigreed-dog immune system?
AB: It is certainly true that my research may find a new MHC-type immunity gene [the major histocompatibility complex mediates the immune system’s white blood cells] that has been lost in many purebred dogs and which could reinvigorate their immune diversity. Or perhaps it will find variants associated with diet, and make us start considering a dog’s genetic makeup when making dietary recommendations. But I’m really not comfortable speculating, since I’m likely to be quite wrong in these predictions.
For example, I would have never guessed that deliberately infecting patients with intestinal parasites [Helminthic therapy] would cure ulcerative colitis, but that seems to be the case, and signatures of selection in the human genome help explain why.
But having said that, I think looking at the genomes of village dogs will be extremely useful. For example, we could get a better picture of the kinds of traits that were selected for in natural dog populations, including disease resistance, which might give us useful insights into diseases we diagnose in our pet dogs.
Conversely, as veterinarians and geneticists find more mutations that cause disease or unique traits in dogs, we can look at the genomes of diverse village dogs to see when and where these mutations arose, and whether they are also found in any other village or purebred dog populations.
It’s a really exciting time to be a canine geneticist, as we have all these new genetic tools at our disposal and many, many purebred and free-ranging populations that have yet to be characterized genetically.
JB: Some populations of village dogs, such as those you’re studying, have been isolated for many thousands of years, evolving under pressures that the stem parents of modern breeds were never exposed to. Is it possible that these dogs have “new” gene variants that don’t exist in the genome of modern breeds?
AB: It’s certainly possible, and it’s something I’m very interested in. For example, my lab is looking at free-ranging dogs in the highlands of Peru to see if they have any genetic adaptations for high altitude. Perhaps more importantly, some village-dog populations might harbor disease-resistant variants for parasites or pathogens that are prevalent in their area, but these variants might not have made it into modern purebred dogs, since those breeds were mostly founded elsewhere.
JB: How urgent is it that we learn more about these ancient dog genomes?
AB: We know how quickly pre-Columbian Native American breeds were lost when Europeans brought dogs with them to the New World, and we see that it will happen like that very soon in other remote parts of the world. So we’re working as fast as we can to get the data before the dogs are gone.
JB: What’s going on in your lab now?
AB: We’re collecting DNA samples and the genetic information we need so we can start piecing together what’s going on in these interesting but largely neglected free-ranging dog populations. We are seeking insights into dog population history to discover patterns of selection around certain genes that can then become the basis of further study. Our work is very hypothesis-driven. We have certain hypotheses about how dogs evolved, and we try to collect the right samples to test these hypotheses.
As geneticists learn more about how genetic variation controls complex traits in purebred dogs, we find it’s quite different than what we see in humans. Why? There are at least two competing hypotheses, and by gathering data from free-ranging dogs, we can start testing them to figure it out. Some of this gets into technical discussion about genetic architecture, recombination, epistasis and pleiotropy and such, so I’ve avoided getting too academic. But I also don’t want to be dismissive of it since those technical, hypothesis-driven aspects of the project are the bread and butter of my lab in terms of student training.
JB: In longitudinal studies such as the Morris Animal Foundation’s Golden Retriever Lifetime Study, researchers gather information from participants’ DNA and then match what they find to traits the test dogs may display over a lifetime. Will you have an opportunity to see how, for example, an immunesystem mutation affects a village dog’s health as it ages?
AB: Our project is a huge undertaking, and there’s a ton of data we’d love to gather on each dog but just simply aren’t able to since, at this point, we’re focused on sampling as many dogs from as many populations as possible to maximize the amount of diversity we can analyze. I really don’t want to overstate what we’re able to do in one visit to check out a dog and draw blood, which is limited to looking for genetic signatures in the genome of these dogs showing signs of selection and/or local adaptation.
But, since we have a fairly good idea of what genes do in modern dogs, at least in a rough sense, if we see a genetic signature in village dogs for positive selection around a gene we know is involved in immune function (for example), that’s a big discovery.
JB: At the risk of oversimplifying, say you’re looking at a region that you know to be linked to a negative trait and you see that the switch is turned off in the village dog DNA and turned on in modern dog DNA—would you feel that you’d found a “smoking gun”?
AB: It’s possible. Then, of course, as you allude, we would want to go back, look at dogs carrying that mutation versus other dogs, and see if there are different health outcomes. Perhaps [dogs with the mutation] are more resistant to intestinal parasites or perhaps they are more prone to autoimmune disease or something. Until we find the mutations, it’s a bit speculative to make predications about what exactly the findings will mean to owners. This is certainly “basic research” in the purest sense.
JB: In people, size is determined by hundreds of genes, each with a small effect. In purebred dogs, body size can be regulated by a single gene. Is this unique to dogs?
AB: It depends. There are other traits in other species controlled by a couple of loci [location of a gene on a chromosome]. I would argue that yes, it’s pretty unique. Whether or not dogs are special in that there is something about their genome that predisposes them to this type of diversity, or perhaps because humans worked so hard at creating them, we don’t know. This debate is still raging in the literature. It is definitely the case that genes have many, many effects. Rather than being a blueprint in which each gene is responsible for just one part of building the whole organism, the genome is more complicated, with each gene taking on different roles at different times or in different tissues.
JB: Do multiple-trait relationships also show up in village dogs?
AB: I think this would also occur in village dogs if the mutations were in those populations. The difference is that selective breeding has actively promoted these large-effect, diversifying mutations in dog breeds, making them relatively more common. Natural selection usually selects against such large-effect mutations in natural populations. You won’t see a short-legged wolf because it couldn’t hunt.
In fact, most of these large-effect mutations probably first arose in village dogs. The difference is that these mutations aren’t usually beneficial to village dogs, but the ones that aren’t too detrimental might persist at low frequency long enough for humans to start trying to promote breeding of that trait. Take achondrodysplasia [a type of dwarfism]. It almost certainly arose in village dogs, but to a free-ranging dog, super-short legs and all that comes with them probably aren’t much of a selective advantage. But once folks started looking for dogs to turn their spits, they found these super-short dogs to be useful, and eventually that genetic variant made its way into a whole host of modern breeds.
For the specific achondrodysplasia mutation, I don’t know if that is the exact story, but I do think this is likely to be the case for many large-effect mutations. Depending on how early in dog evolutionary history the mutation arose, it could be found in most regional village dog populations, or it could be restricted to certain populations that are close to where it first arose. Lots of research still left to be done!
JB: As a lifelong dog lover, you must find it difficult to see the deplorable conditions in which some of these dogs live.
AB: There’s so much disease in these high-density populations. As these communities become more urbanized, dogs are living like rats and pigeons. Getting DNA on these populations is not enough of a reason to allow the animals to exist like this. Life on an urban street is rough existence.
JB: If you adopt a village-dog puppy and raise it in a typical Western environment, what kind of dog will you have?
AB: Adopting the dogs is not part of our project, but we know people who have done this. They can be great dogs. They don’t have some of the aggression issues you might see in some of our dogs, because they are culled for aggression, or for eating a chicken. There are some things that aren’t tolerated. So you might say that people in the villages impose a form of selection. The dogs are smart and resourceful. They seem to adapt.
Culture: Science & History
"Though in their deep heart’s core, there is a commonality of origin, spirit, emotional intelligence and empathetic sensibility, the wild wolf looks through us, while the dog looks to us. "
Of all the myriad members of the animal kingdom, the domesticated dog (Canis lupus familiaris) is closest to us. With individual exceptions in other species, this canine species is the most understanding, if not also the most observant, of human behavior—of our actions and intentions. This is why dogs are so responsive to us, even mirroring or mimicking our behavior. And it is why dogs are so trainable.
Fear in unsocialized and abused dogs interferes with their attentiveness to and interpretation of human behavior and intentions. This is one reason wild species like the coyote and wolf, even when born and raised in captivity, are difficult to train. The wolf “Tiny,” whom I bottle-raised and intensely socialized during her formative early days, never really lost her fear and distrust of strangers.
Tiny did not start mirroring human behavior until she was close to nine years old. At this point, she began to mimic the human-to-human greeting grin, revealing her front teeth as she curled her lips into a snarly smile. In my experience, dogs who can do this do so at a much earlier age, even as early as four to six months.
In comparing socialized (human-bonded) wolves and dogs in terms of how they have related to me as well as to my family members, friends and strangers, I would say that the main difference between the two species is the fear factor. Differences in trainability hinge on this; as I theorize in my new book (Dog Body, Dog Mind), domestication has altered the tuning of the dog’s adrenal and autonomic nervous systems. This tuning (which dampens adrenal fright, flight and fight reactions and possibly alters brain serotonin levels), is accomplished through selective breeding for docility, and by gentle handling during the critical period for socialization.
According to the earlier research of my mentors—Drs. John Paul Scott and John L. Fuller of the Jackson Laboratory in Bar Harbor, Maine—pups with no human contact during this critical socialization period (which ends around 12 to 16 weeks of age) are wild and unapproachable.
When we peel off the wolf’s innate fearfulness and put it on the dog, we turn the dog into a feral facsimile of a wolf. But a human-socialized wolf without fear could be an extremely dangerous animal, even attacking a human perceived as a pack rival. This happened to me in the 1970s during the filming of the NBC documentary, “The Wolf Men.” An alpha male wolf, along with his female cagemate who was in heat, had been released into a large wooded compound belonging to my friend, the late wildlife illustrator and conservationist Dick Grossenheider. Earlier that memorable morning, the she-wolf had greeted and solicited me, a total stranger, when I had visited the two wolves in their enclosure. (I am not saying that a male dog would never react to me in a similar way under comparable circumstances; I was once urinated on by the alpha male lead sled dog of a well-known racing pack in a similar situation.)
Canine Evolution and Human Needs
We see many things in our dogs’ eyes, the windows of their souls. They are also mirrors of the human soul, since every pair of dog’s eyes reflects—for better and for worse—how well that dog has been treated by our own kind. Dogs read our eyes and are attentive ethologists of human behavior, action, emotion and intuition. A change in tone of voice can make a dog tremble in fear or dance and yap for joy. Such ability to read human behavior, intentions and emotions was naturally selected for as dogs domesticated themselves and adapted to life with Homo sapiens, the “killer ape.”
Civilizing the Killer Ape
These half-human killer apes were never to be fully trusted, however, since when they were very hungry, or warring between themselves, they would often engage in cannibalism, as today, people still kill and eat dogs for sustenance and “good medicine.” (See James George Frazer’s The Golden Bough.).
Just as not every dog is fully domesticated, in that some can still turn feral, and others turn on their masters, so the wolf has failed to fully domesticate and civilize the killer ape. We still wage war with our own kind, and ignore the biological wisdom and prescience of such injunctions as do no harm, resist evil and treat others as we would have them treat us. All good dogs know this, and show it in their eyes and behavior. (But they have not forgotten how and where to bite!)
The secure, well-loved and understood dog is more often an extrovert than an ambivert wary of strangers. Secure, well-loved and understood wolves, in contrast (with few exceptions, some of whom become more easy-going around new people and in new places as they grow older, as did Tiny in her early teens), are more often ambiverts or introverts. They are fearful when meeting unfamiliar people. Differences in individual, breed and species autonomic tuning (as mentioned earlier) also account for differences in disease resistance, temperament and learning ability.
The Canid Conscience
Good dogs can see and respond to our own deep heart’s core of love and devotion because it is from this center of our own being that we embrace and celebrate theirs. That is what Franz Kafka in his essay, Investigation of a Dog, meant, I believe, when he wrote: “All knowledge, the totality of all questions and all awareness, is contained in the dog.” And this is why the ancient Egyptians believed that dogs were our guide in the afterlife—they were such good guides and loyal companions in real life. Embodying finer qualities of feeling and sensibility than the relatively irresponsible and emotionally challenged average human, dogs are worthy of being looked up to with awe and gratitude. We should help others of our own kind feel and know that in the deep heart’s core of all good dogs and wild wolves lies the source of an abiding affection that we, in moments of grace and communion, may share.
Since this core is as evident in a wolf as it is in a Toy Poodle, it is clear that neither domestication nor wildness has altered their true natures. In the heart of every dog is the spirit of the wolf that embodies the finer qualities of human nature that we call love and devotion.
There is a really interesting article posted on The Atlantic site today about the popularity of large dogs in China. As the author Damien Ma notes, “Most Americans will likely have a preconceived notion of the Chinese relationship with dogs. When a developing country can barely take care of all its own people, animal rights tend to sit very low on the totem pole. But the reality is much more complicated, especially with a burgeoning dog culture associated with the rise of young urban elites with disposable income. “
Ma then interviews an American filmmaker who is making a film Oversized Dogs: Chinese Dog Laws and the People Who Break Them. The director, who remains nameless for now, has been interviewing Chinese dog lovers who, similar to many dog lovers in other countries, find laws pertaining their pets onerous at worst, and turning many into scofflaws . But this isn’t a simple examination of a rising middle class pleasure in having dogs and their attachment to pets, it really does say more about how societal attitudes in China are evolving. As the director remarks: “From this, I realized that Chinese individuals casually break laws everyday, and this constitutes a very subtle and interesting side of dissent.” Read the whole interview and find out more about this Chinese “secret dog society” and what it might portend for the future of dogs in the world’s most populous country.
News: Guest Posts
I had watched the dog origin wars as a chronicler of the dog-human relationship for several decades when in 2009 I was approached a young editor The Overlook Press about writing a book on the origins of the dog. I readily agreed, and the result was How the Dog Became the Dog.
Pondering the conflicting dates, places, and theories associated with the emergence of the dog, I concluded that as soon as our forebears met wolves on the trail they formed an alliance of kindred spirits, and the process began. Their basic social unit was a family with ma and pa at the head and young ones of varying competency. They worked and hunted cooperatively. They were consummately social but capable of prolonged solo journeys.
It made sense that the Middle East, if not North Africa, was where this all started because that would have been the region of first contact. But because of their natural affinity, wolves and humans got together wherever they met. Some of the resultant “dogwolves”—my phrase for doglike wolves or wolves that act like dogs—created lineages that survived a while then fizzled out; others endured.
I identified several hotspots for early dogs across Eurasia and a group of humans that at least according to genetic evidence might have made its way through the cold of the last Ice Age from the Persian Gulf oasis, then a fertile land, to the Altai Mountains of Central Asia, a region that also hosts the headwaters of the Amur River, still famous for its wildlife. This group’s dogwolves mixed and matched with others along the way, especially the big mountain dogs of the Caucasus. This group of hunters and foragers gathered in the Altai around 40,000 years ago and from there ultimately took the New World.* They also went with their dogs, I calculated, south and east into China, Korea, and Japan and west again with their giant dogs, now mastiffs.
I based that conclusion in part on the types of dogs found in the New World. It made more sense that the possibility for the phenotype was present even if the phenotype itself was not manifest than that it was introduced later.
It was with some interest, then, that I read in PLoS One for July 28, 2011, about a 33,000 year old ‘incipient” dog from the Altai Mountains—that is, an early attempt at a dog that went nowhere. The finding was immediately challenged, and the fossil dismissed as a wolf, even if a strange one. So a new team of researchers redid the work in Robert K. Wayne’s evolutionary biology lab at UCLA and on March 7, 2013, published an article in PLoS One confirming that the 33,000 year-old-fossil is that of a primitive dog.
Writing for their colleagues from Russia, Spain, and the U.S., Anna S. Druzhkova of the Siberian Branch of the Russian Academy of Sciences and Olaf Thalmann of Turku University, Finland, state that when compared with other canids, the Altai dog, as it is known, shows closest affinities with New World dogs and modern dog breeds, ranging from Newfoundlands to Chinese Cresteds and including cocker spaniels, Tibetan mastiffs, and Siberian huskies.
Equally interesting from my perspective, the Altai dog does not appear to have been related closely to wolves in its immediate vicinity or to modern wolves. It came to the Altai from elsewhere, probably with people.
The researchers emphasize that there is uncertainty in their findings because they are based on a single region of mitochondrial DNA. But from my standpoint, the work provides one bit of evidence that’s I’ve not been barking up the wrong tree—and that seems worth noting.
*Ted Goebel et al., “The Late Pleistocene Dispersal of Modern Humans to the Americas,” Science, March 14, 2008. Connie J. Kolman et al., “Mitochondrial DNA Analysis of Mongolian Populations and Implications for the Origin of New World Founders,” Genetics, April 1996.
Culture: Science & History
Which DNA test should you choose to settle the “what’s in the mix” question?
For years, you’ve argued with your spouse that the 60-pound, black-and-tan tennis ball–chaser who takes you for walks and sweeps the coffee table clean with his tail is a German Shepherd mix, and that there is absolutely no Doberman Pinscher in there. Finally, in order to end the breed debate once and for all and restore peace to your household, you’ve decided to settle the question with a mixed-breed analysis test.
You’ve heard of the “swab test” and the “blood test” and know that both claim to unravel breed ancestry. With a little more research, you discover that the world of canine heritage tests has expanded since the first tests became available in 2007. Having a choice is great, but how do you go about comparing them and choosing the one that’s right for you?
There are several factors to consider, including the type of sample required, the number of breeds that can be identified, costs, turnaround times and the way the results are reported. Before you commit to a test that will decide the outcome of the German Shepherd/Doberman Pinscher battle, be sure you understand what you’ll be getting.
MetaMorphix Inc. (MMI) Genomics administers the Canine HeritageTM Breed Test, commonly referred to as “the swab test,” and Mars Veterinary provides “the blood test,” the Wisdom PanelTM MX Mixed Breed Analysis. These two companies have been considered the main players in this market, but new contenders are flocking to the scene. The most recent challengers are DNA Print Genomics, which offers the Doggie DNA Print, and BioPet Vet Lab, which recently unveiled the Dog DNA Breed Identification Test. Both use cheek swab samples.
The swab sample has the advantage of a collection procedure that is simple enough to be done by the owner at home. It does have some drawbacks, however, including a risk of contamination and too few cells being obtained for successful testing. To avoid the latter, BioPet Vet Lab includes a card that changes color to indicate that a sufficient sample is present. Blood samples are collected by a veterinarian and the chances of contamination and inadequate sample size are greatly reduced.
Tests also differ in the number of breeds available for comparison. Mars Veterinary interrogates the genetic signatures of more than 130 of the 159 breeds recognized by the American Kennel Club (AKC).* MMI Genomics recently announced the XL version of their test, which has a database of more than 100 breeds. The breed list available for BioPet Vet Lab contains 58 breeds. DNA Print Genomics does not report specific breed matches; rather, “15 elements of dog ancestry” are revealed, and the customer performs a search of the company’s online database to identify matches to particular breeds. Since each test interrogates a different set of breeds, sending your dog’s sample to more than one company may not return identical results.
Cost and turnaround times vary from test to test. In the past, the cost of the Wisdom Panel MX Mixed Breed Analysis test was determined solely by individual veterinary clinics, but the test can now be purchased online for $124.99, and test results are available within three to four weeks. (Your veterinarian will still have to draw the blood sample.) The swab tests are sent directly to the owners for sample collection, and prices and turnaround times vary: Doggie DNA Print, $199, six to nine weeks; Canine Heritage XL Breed Test, $119.95, four weeks (if you submitted a sample for the original version of the Canine Heritage Breed Test, you can purchase an upgrade to the XL version for $55 online); and the Dog DNA Breed Identification Test, $57.95 to $59.99, two weeks. (Prices current at press time.)
Results are presented as a certificate or report, depending on the company. MMI Genomics provides owners with a Certificate of DNA Breed Analysis. Three breed categories are included in the results: Primary, Secondary and In the Mix. BioPet Vet Lab’s Ancestry Analysis Certificate reports breeds in your dog’s genetic background in order of prevalence; a paragraph about each breed as well as a behavior, health and personality summary are included.
A report from DNA Print Genomics includes genotypes, ancestral population results and 15-N population results. Ancestral population results indicate your dog’s relationship to each of the four most basic branches of the canine family tree—wolf-like, hunters, herders and Mastiffs—while 15-N population results are a set of numbers that compare a sample to groups of breed signatures in the database. Each owner is given an ID and password that are used to query the online database for matches to specific breeds.
The Mars Veterinary report presents images of the breeds present in your dog’s ancestry, with the relative size of the image indicating the prevalence of each breed. An appearance, behavior and history section describes characteristics of each identified breed that might be seen in your dog.
As the companies run more tests and add breeds to their databases, the accuracy of the results may improve. It is also possible that even more companies will enter the canine breed ancestry DNA test field. When deciding where your dog’s sample will be submitted, determine what you want to learn and educate yourself about each of the tests. All of the companies agree that working with your veterinarian will ensure that you get the most out of your results. Who knows, choosing the test that best matches your needs could do more than just earn you a victory in the great German Shepherd/Doberman Pinscher debate!
*None of these tests are designed to identify purebred dogs, and the AKC will not accept test results for registration purposes.
Want to read more about dogs and DNA? Click here.
News: JoAnna Lou
The doomed ship's survivors included three canines
April 2012 marks the 100th anniversary of the sinking of the Titanic. Knowing that only 31 percent of the ship's human passengers survived, I was surprised to learn that three dogs made it safely to New York.
Only first class passengers were allowed to bring dogs on the voyage and many belonged to prominent families. There were 12 confirmed dogs on board the Titanic including a Toy Poodle, a Fox Terrier, a French Bulldog and millionaire John Jacob Astor's Airedale named Kitty. The three survivors were all small enough to be smuggled onto the lifeboats—two Pomeranians, one named Lady, and a Pekinese named Sun Yat-Sen who belonged to the Harpers, of publishing firm Harper & Row.
Most of the dogs did not live in the cabins with their family and instead were cared for by crew members in the ship's kennel. Some of the pets were even insured, but mostly because they were considered property. However, that wasn't the case for all of the dogs aboard the Titanic.
There are many heartbreaking stories that came out of the disaster, but as a dog lover, I'll never forget the one about Ann Elizabeth Isham and her beloved Great Dane. Although many passengers regarded their animals as material possessions, Ann was said to have visited her dog every day at the ship's kennel.
Legend says that when Ann tried to evacuate with her Great Dane, she was told that he was too large. Ann refused to leave without him and got out of the lifeboat. When a recovery ship toured the wreckage days later, the crew spotted the body of a woman holding onto a large dog. It's assumed that the bodies recovered were that of Ann and her Great Dane, but the information is unverified. However, whoever the woman and dog were, one thing is for sure—they were there for each other until the very end.
Culture: Science & History
Unraveling the genetic tapestry provides clues to breeds and their mixes
A mongrel dog is like a box of chocolates: You never know what you’re going to get. And therein lies the appeal. What’s more fun than serendipitous unpredictability all bundled up in puppy fur? But when that puppy grows up, we inevitably make assumptions about her ancestry based on how she looks and behaves. Our logic goes like this: “If my pooch is long and low to the ground, and she never barks, she must be a Corgi/Basenji mix.”
But it’s much more complicated. The genes—and there may be hundreds—that work together to make a Corgi look like a short-legged Shepherd may be completely different than those responsible for a Basset Hound’s low-slung carriage. With some exceptions, scientists cannot yet connect genetic dots to specific traits. But they have discovered something tangible that measures some of the differences between breeds: genetic patterns of organization displayed on a scatter graph that answer the question, “What’s the same and what’s different?”
A scatter graph provides a symbolic visualization of DNA, wherein each individual dog contributes one point. The resulting pattern indicates the type and strength of the relationship between individuals. The more the points cluster around each other, the more alike they are.
In addition to simplifying methods used to find markers for breed-related disease, the researchers identified patterns of “breedness” and tracked the history of breed DNA. At the same time, by following mitochondrial DNA, genetic material passed down from mother to offspring without changing, they traced the breed’s journey.
Depending on how much time is attributed to a generation and how many generations are involved, scientists can estimate how much time has passed. Based on this tracking, it has been suggested that it took 5,000 years to develop and refine a handful of the world’s 350-plus breeds, and about 400 years to create the rest.
Research indicates that four distinct breed groups are ancient: (1) Middle Eastern Saluki and Afghan, (2) Tibetan Terrier and Lhasa Apso, (3) Chinese Chow Chow, Pekingese, Shar-Pei and Shih Tzu; Japanese Akita and Shiba Inu, (4) Arctic Alaskan Malamute, Siberian Husky and Samoyed. Although the 13 breeds look different, they are so closely related that they are represented by a single genetic cluster. It’s likely they all originated from the same stem-parent—proto-breed, if you will—who roamed the Asian continent.
As humans migrated from one place to another, this ubiquitous proto-breed trotted along, bringing with her the ingredients needed to cook up all the breeds we’re familiar with today. Her offspring performed work unique to each geographical region, such as hunting, hauling or guarding. Isolated and mating only with each other, “accidental” breed types exhibiting consistent shape, color and behavior emerged.
No matter what historians might claim—scent hound to sight hound, bird dog to bad dog—evidence produced through genetic research indicates that all remaining breeds have been concocted in the last 400 years. Although closely related to one another, they can be identified as distinct based on the way their DNA separates.
How They Do It
“We look at ’breedness‘ among dogs. Our canine database is built with 10,000 samples of 108 breeds. We ran 400 markers to identify the best markers for a ’breedness‘ test against 38 breeds. We created a panel of 96 pieces of DNA that split dogs into their identified pure breed. In our preliminary test, we found that individual purebred dogs cluster with other purebreds.” Initially, MMI chose 38 AKC registered breeds from their database, selected for their popularity based on number of registrations. Recently, as DeNise notes, they increased the number to 108 breeds. This jump in breed recognition required testing thousands of markers to identify the just over 300 markers that characterize these 108 breeds.
Breeds are created a number of ways. In simple terms, when breeders interfere with natural reproduction and rigorously select for traits favored by humans, specialized breeds like Retrievers, Spaniels, Hounds and Terriers are the result. Saving spontaneous mutations in a litter of dogs, repeating the breeding to get more of the same mutation, and breeding those dogs back to one another has resulted in the English Bulldog, Chinese Crested and Inca Hairless. More recent breeds, such as the Airedale, Australian Cattle Dog and Doberman, are the result of crossing older breeds to make new ones.
When kennel clubs closed gene pools in the late 19th century to suspend change in registered dogs, breeds drifted toward a more uniform stereotype. Until the early 1800s, an assortment of dogs with similar talents who could produce somewhat similar offspring were awarded the right be called a breed. Breeds evolved, flourished and disappeared when jobs were eliminated. Tumblers, who mesmerized prey by “winding their bodies about circularly, and then fiercely and violently venturing on the beast,” disappeared when guns came into widespread use. Turnspit dogs, who made a living running on a wheel to turn meat so it would cook evenly, received their pink slips when technology improved cooking methods.
By and large, Victorian society was not so pragmatic; sentimentality and commercial opportunity were catalysts for saving unemployed breeds from their inevitable demise. As a result, many Terrier breeds went from killing varmints in the barnyard to killing time in the Victorian parlor in less than a decade.
Whereas previously, a breed was a regional product maintained and preserved by a small community of knowledgeable people, commercial interest in the well-bred pet dog initiated a shift in breeding practices during the Victorian era. The old-money kennels operated as a pastime by the wealthy gave way to a large number of small, commercially operated kennels run by entrepreneurs of modest means and experience.
Germane to this tale is that, according to the unwritten rules governing canine physiology, anatomy and behavior go hand in hand. One cannot be changed without affecting the other. Victorian enthusiasts who were busily adding aesthetic traits to utilitarian breeds were creating not only subtle variations in type, but in many cases, modifications in behavior as well. As utilitarian breeds went from working hard to hardly working, many exhibited new physical and behavioral characteristics that were compatible with their augmented duties as companion animals. Breeders claimed the “sub-breeds” as their own, made up new names and registered each one.
However, no matter how they’re sliced and diced, reducing and suppressing genes so they aren’t expressed doesn’t mean they’ve been eliminated. They’re still lurking and, depending on the method used to analyze the DNA, the lurkers often show up in the results.
Most people assume all mixed-breed dogs had a purebred ancestor at some time in their recent heritage. But in fact, this is not necessarily the case. When you run a mongrel’s DNA through a computer program, the algorithms attempt to group breeds together on a scatter chart. If the heritage of the dog is such that it is not in MMI’s database of 108 breeds, the program tries to find varieties that are most alike. Because at least one or two of the handful of ancient breeds are in every modern dog, sometimes the program will identify an ancient breed in the mix. “In the report we send to the client, we use the terms ‘primary,’ meaning the majority of the DNA matches a breed; ‘secondary,’ meaning less than the majority of the DNA but a strong influence nonetheless; and ‘in the mix,’ meaning the least amount of influence,” DeNise notes. That’s how you might get an obscure breed in the report. For instance, a 35-pound mongrel with a tablespoon of Husky and a teaspoon of Border Collie may also have a dash of Borzoi, because before gene pools were closed a century ago, Huskies were crossed with coursing hounds to add speed.
Don’t Judge a Pup by Her Cover
Researchers are intrigued by data that suggest expressed traits are somehow turned “on” and “off” by other genetic components, thus causing the wide variations in canine form and behavior. For instance, it’s possible that many breeds have the genetic potential for a black tongue, but only a few breeds have the molecular mechanism to switch that color on. So that black-tongued mutt may not have any Chow in the mix after all.
On the other hand, the results may show that a quintessential Heinz 57 has the genetic makeup of a single breed and it could be one she looks nothing like.
DeNise explains it this way: “In a population of any breed, there are dogs that are carriers but don’t exhibit phenotype [observable characteristics]. If you reduce the size of breeding population—creating what we call a bottleneck—you start increasing the frequency of deleterious traits, like dwarfism or white coat. If we looked at the DNA of, for instance, a group of white mini-German Shepherds, they would probably cluster with German Shepherds. After they’ve intermated for five to six generations, we may not come up with that. They would cluster with each other. If breeders were changing allele frequencies quickly, you could do it very fast.
“There are always contradictions that make you say, ‘Huh, that’s really weird.’ One odd thing that happens is due to some sort of random assortment of genes in mixed-breed dogs. The algorithm may identify a breed that is not consistent with the physical appearance of the dog. We sometimes get an indication of this when the certificate is printed with the picture of the dog provided by the owner, and the certificate is reviewed by our customer service department prior to mailing it to the pet owner.”
A 90-pound, wiry-haired mongrel who swims, chases balls and makes goo-goo eyes like a Golden Retriever and whose only pedigreed relative is a very distant Chihuahua confounds the process, but says a whole lot about the complexity of canine genetics and why some scientists devote their careers to studying canine evolution. Extreme variation in anatomy and behavior is unique to the domestic dog. If humans were an equally anomalous species, we’d weigh between 20 and 650 pounds and range in height from three to 10 feet. In dogs, adaptations change with such speed that scientists suspect there may be a clue in the canine genome that could reveal how evolution works.
Sorting It Out
MMI can’t as yet define the percentage of “breedness” in mixed-breed dogs. One reason is that some breeds cluster loose and others tight. Why this happens isn’t clearly understood. German Shepherds, Standard Poodles and Collies cluster tight. Miniature Poodles cluster tight, but Toy Poodles cluster loose. Within their breeds, Labrador Retrievers and Beagles often cluster as two different groups. According to DeNise, “Labs from the United Kennel Club that are bred specifically for hunting and AKC Labs do not necessarily cluster as one breed. And AKC Beagles and Beagles bred specifically for research don’t cluster together either.”
She adds, “In my opinion, it’s possible that a population that increases rapidly doesn’t cluster as well as those populations that have remained static. This is because, as you increase a population to accommodate breed popularity, people breed everything, including animals that may not exhibit all the physical characteristics that are desirable.”
And even when dogs look alike, they can display behavioral differences. As DeNise notes, “We understand so little about how behaviors are coded. Many behaviors are learned, but there are probably multiple genes that are responsible for herding, birding, heeling—these kind of hard-wired behaviors.”
Scientists are eager to tease out genetic connections to breed-associated motor patterns. When wolves hunt, they display these behaviors sequentially: orient > eye > stalk > chase > grab-bite > kill-bite > eat. Artificial selection, however, extracts and segregates these patterns in incomplete sequences. In certain breeds, individuals perform the abbreviated motor pattern repeatedly. A Pointer who stops dead in her tracks and stands stock still with her front leg held rigid in mid-stride to indicate the presence and position of game is the lofty goal of bird-dog breeders. To wolves, it’s just a good meal interrupted.
Combinations of canine anatomy and behavior push and pull one another along in a rhythm of interconnected patterns in relationships that may not be as random as they appear. Like principal components of an automobile in which the size of the engine and the weight of the body directly affect efficiency, it appears that dogs, too, have integral parts wherein one component is proportionate to the other.
Researchers don’t fully understand the relationship, but they are making headway. As reported in Genetics (June 2008), a team of scientists identified a few single genes that regulate systems controlling skull shape, weight, fur length, age span and behavior. Because mutts are combinations of DNA from different breeds, they may hold the answer to how the genes influence multiple traits.
Scientists suspect that many evolutionary secrets are hidden in the dog genome. For dog lovers, deconstructing Molly or Max’s mixed-breed heritage is an interesting intellectual mystery to be discussed at cocktail parties or the dog park. For scientists, their genetic material is nothing less than an instruction manual for species building. Whereas populations evolve over the course of millennia through the process of natural selection, dogs can change so rapidly and abruptly that they represent evolution at hyperspeed. How it happens remains a puzzle. Now scientists are looking to mutts to find the missing piece.
News: Karen B. London
Happy accident launched the toy
Louis Pasteur’s remark “Did you ever observe to whom the accidents happen? Chance favors only the prepared mind” is true in many fields. Those who have great knowledge recognize opportunity and are able to take a random event and recognize the value of something unexpected.
In the world of dogs, a great example of chance favoring the prepared mind is seen in the original inspiration for the Kong toy. Inventor Joe Markham, founder of The Kong Company, received his inspiration from a surprising source.
He was working on his vehicle and tossed an axle stop with an attached bracket on the ground. His dog got hold of it and loved it. He was playing with it joyously, much to Markham’s amusement. He said to his friend, “What do you think of my new dog toy?”
His friend replied, “Actually, it’s not too pretty. It looks like an earplug from King Kong.” And the Kong toy was born.
I heard this story from Mark Hines, behavior and training specialist for The Kong Company, who gave a talk at a conference on applied animal behavior that we both attended this past weekend. The conference had many great talks and I learned so much, but this one brief story stands out more than any other piece of information. I’ve often wondered how Kong came up with their well-known and trademarked shape.
News: Karen B. London
Woven items of the Coast Salish
Wearing dog hair has become acceptable to the point that many people believe no outfit is complete without it. The contribution of canine fur to textiles is hardly new, though.
Before European contact, the Coast Salish people of the Pacific Northwest incorporated dog hair into their textiles, including robes, sashes and blankets. Oral histories have long claimed this, and a recent scientific study has confirmed it. Pieces as old as 200 years that are stored at the Smithsonian's National Museum of Natural History and National Museum of the American Indian were analyzed using protein mass spectronomy.
All items prior to 1862 contained dog hair, but pieces from the late 1800s and early 1900s did not. No items were made entirely of dog hair, leading scientists to believe that dog hair was a supplemental material. Mountain goats were the primary source of wool, though commercial sheep wool was in some items as well. Ceremonial items were made of goat hair alone, while everyday items also included dog hair.
Museums have labeled blankets made by Coast Salish people as “Dog Hair Blankets” but this study suggests that those descriptions need to be updated.
Dog hair is used to make fibers for knitted and crocheted objects in our culture, too, and the yarn spun from dog hair can be of a very nice quality. Of course, most of us still just wear the fur of our canine pals in an ad hoc, purely decorative way, which always looks good. If you love dogs and wear dog hair, you’ll always be fashionable—good taste never goes out of style.
News: Guest Posts
With backstories to match
First there was Owney the original—a Terrier-mix stray who became the loveable canine mascot of the Railway Mail Service. Then, there was Owney the stamp. Next, Owney the iPhone app and Owney the star of the interactive e-book Tails from the Rails (to be released later this fall). And, finally, Owney look-alikes.
I could suggest this is overkill, except that not only do I find all the Owney spin-offs nearly as adorable as their inspiration, I’m smitten by the finalists of the Owney look-alike contest, especially the winner, a 5ish former stray from California named Bentley.
More than 70 dogs across the country lounged on mailbags, dressed up in letter-carrier uniforms and posed by mailboxes for the contest sponsored by the National Postal Museum and the Washington Humane Society. Second and third prize went to Jordy from Virginia and Murphy from Ohio. Not only do all three dogs look the part, as rescue pups they lived the part too. Read their stories at the National Postal Museum’s website.
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