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Scientists Searching for Clues to The First Dog

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.

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Submitted by Anonymous | May 24 2013 |

Regarding the title of the topic "Scientists Searching for Clues to The First Dog", the Archaeological Institute of America has a few articles worthy of review:

May 22, 2013 - Prehistoric Dogs Were More Than Hunting Companions

EDMONTON, CANADA—Robert Losey of the University of Alberta studied prehistoric burials of dogs [http://news.discovery.com/animals/pets/prehistoric-dog-lovers-profiled-1... around the world. He found that dog burials were more common in regions where the human population was dense, the dead were buried in cemeteries, and people ate a lot of aquatic foods, even though it had been thought the dogs were kept by humans primarily for hunting terrestrial game. In Eastern Siberia, where dog domestication is estimated to have occurred 33,000 ago, dogs were only buried for the past 10,000 years, and then only when a human was also being buried. “I think the hunter-gatherers here saw some of the dogs as being nearly the same as themselves, even at a spiritual level. At this time, dogs were the only animals living closely with humans,” Losey said. For example, one dog had been buried wearing a necklace made of four red deer tooth pendants, a human fashion at the time.
http://www.archaeology.org/news/896-130522-domestication-dogs-burials

May 20, 2013 - Are Dogs and Humans Evolutionary Partners?

BEIJING, CHINA—Geneticist Guo-dong Wang of the Chinese Academy of Sciences and his team analyzed the DNA of four gray wolves, three indigenous Chinese dogs, a German shepherd, a Belgian Malinois, and a Tibetan mastiff. Their results indicate that gray wolves split from Chinese dogs some 32,000 years ago. They then compared corresponding genes in dogs and humans, and found that domestic dogs and their human partners experienced similar changes in digestion, metabolism, and brain chemistry as they evolved together. “As domestication is often associated with large increases in population density and crowded living conditions, these ‘unfavorable’ environments might be the selective pressure that drove the rewiring of both species,” the team wrote.
http://www.archaeology.org/news/885-130520-dogs-humans-domestication-gen...

Thanks for the opportunity to show my enthusiasm as a animal lover. Please don't forget that we are from the animal kingdom too.:) Loving an animal is what makes life beautiful!

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