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Scientists Searching for Clues to The First Dog
Village dogs’ genetic code may hold clues to canine evolution and health
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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.

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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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