Many of the conformational traits we think of as classic for a certain type of dog have their origins in this era. Scroll through pictures of dog breeds from years ago compared to their current counterparts and you can see the dramatic changes that have occurred as dog fanciers selectively bred for traits such as shorter legs Dachshunds were taller back then , and stockier build German shepherd dogs were lankier at the turn of the last century.
Breeding for conformational traits continued through the 20th century. The downside of this extensive breeding program was the loss of genetic diversity, and conformation changes that had detrimental breed-specific health consequences, including the development of undesirable diseases. Canine companions spontaneously develop some of the same diseases that plague humans, such as cancer, heart disease and obesity.
Researchers hope that dogs might shed light on how these conditions develop, ultimately leading to treatments that could help both species. One such study is the Morris Animal Foundation Golden Retriever Lifetime Study that is gathering lifestyle and genetic information on more than 3, golden retrievers.
This groundbreaking project will provide a wealth of new information that will help identify risk factors for canine diseases, including many cancers. This study also has many translational components that may inform human health risk factors. Morris Animal Foundation was one of the first organizations to recognize the potential of genetic research not only in dogs, but in cats, horses and llamas.
By unlocking the genetic code, Foundation-funded researchers have discovered new therapy targets, genetic abnormalities underlying disease, and greater understanding of the problems afflicting our beloved companions. However, scientists are still working to understand exactly what species gave rise to dogs. When dogs broke off from their wild ancestors is also a matter of mystery, but genetics suggest that it occurred between 15, and 30, years ago.
Perhaps wolves started down this path simply by eating human scraps. Many generations later, humans might have encouraged wolves to stay near by actively feeding them. Later still, those wolves may have been welcomed into the human home and eventually bred to encourage certain traits. All of this is thought to have unfolded over thousands of years.
Today, many of the dogs you know and love are the product of selective breeding between individuals with desirable traits, either physical or behavioral. For instance, around 9, years ago , ancient peoples began breeding dogs that were best able to survive and work in the cold.
These dogs would become the family of sled dogs—including breeds such as huskies and malamutes—that remains relatively unchanged today. Similarly, humans bred German shepherds for their ability to herd livestock, Labrador retrievers to help collect ducks and other game felled by hunters, and sausage-shaped Dachshunds for their ability to rush down a burrow after a badger.
Many more breeds were created to fill other human needs, such as home protection and vermin control. Certain breeds have also been created to make dogs more desirable as companions. For instance, the labradoodle, which combines the traits of a Labrador retriever and a poodle, was invented as an attempt to create a hypoallergenic guide dog. While people rely less on dogs for daily tasks than they did in the past, there are still many modern jobs for pooches.
They can also help conservationists find and protect endangered species using their super-powered schnozzes. They assist search and rescue teams in the wake of natural disasters or reports of people lost in the outdoors.
Dogs trained to warn of hidden explosives and enemies serve as allies in military operations. Other dogs assist police looking for jail escapees or the bodies of murder victims. Some partner instead with customs officials searching for contraband, from drugs to elephant ivory.
Larson adds that his gene-focused peers are ignoring one crucial line of evidence—bones. If dogs originated just once, there should be a neat gradient of fossils with the oldest ones at the center of domestication and the youngest ones far away from it.
Instead, archaeologists have found 15,year-old dog fossils in western Europe, 12,year-old ones in east Asia, and nothing older than 8, years in between. A dual domestication makes more sense. But even Larson is hedging his bets.
We lack the smoking gun. Why is this so hard? Of all the problems that scientists struggle with, why has the origin of dogs been such a bitch to solve? For starters, the timing is hard to pin down because no one knows exactly how fast dog genomes change. That pace—the mutation rate—underpins a lot of genetic studies. It allows scientists to compare modern dogs and ask: How long ago must these lineages have diverged in order to build up this many differences in their genes?
The resulting ebb and flow of genes has turned their history into a muddy, turbid mess—the homogeneous soup that Larson envisages. Wolves provide no clarity. Grey wolves used to live across the entire Northern Hemisphere, so they could have potentially been domesticated anywhere within that vast range although North America is certainly out.
The study informally known as the Big Dog Project was born of frustration. Back in , Larson was working hard on the origin of domestic pigs, and became annoyed that scientists studying dogs were getting less rigorous papers in more prestigious journals simply because their subjects were that much more charismatic and media-friendly. So he called up his longstanding collaborator Keith Dobney.
Right from the start, the duo realized that studying living dogs would never settle the great domestication debate. The only way to do that was to sequence ancient DNA from fossil dogs and wolves, throughout their range and at different points in history. While other scientists were studying the soup of dog genetics by tasting the finished product, Larson would reach back in time to taste it at every step of its creation, allowing him to definitively reconstruct the entire recipe.
In recent decades, scientists have become increasingly successful at extracting and sequencing strands of DNA from fossils. This ancient DNA has done wonders for our understanding of our own evolution. It showed, for example, how Europe was colonized 40, years ago by hunter-gatherers moving up from Africa, then 8, years ago by Middle Eastern farmers, and 5, years ago by horse-riding herders from the Russian steppes. Larson originally envisaged a small project—just him and Dobney analyzing a few fossils.
But he got more funding, collaborators, and samples than he expected. He and his colleagues would travel the world, drilling into fossils and carting chips of bone back to Oxford. While primitive man may not have been very concerned with sanitation, rotting food stuff does smell bad, and also attracts insects that make humans uncomfortable. Thus it is likely that dogs were initially tolerated around the perimeter of the camps because they would dispose of the garbage and eliminate these nuisances.
Let us flash back now to our human settlement where the ancestors of dogs are pawing through the garbage heaps for food. Over time, these particular wolves have not only come to look at this area as their home range, but have, ultimately, become dependent on human refuse as their primary food source.
Although they are tolerated because they remove waste material, any that appear to be a threat to the residents of the settlement are killed or driven away. This culling process alone starts to trigger some genetic changes in these wolves by eliminating the most aggressive members of the pack from the pool of available breeders.
Wolves, like humans, have individual variations in personality. This means that, in the pack of garbage-eating canines, some animals are a bit less fearful and suspicious than others, and, living near humans, these have a definite advantage. This provides the less fearful canines with two benefits: first, they expend less energy than those who run, and, second, they have more time to feed and select the better, more nutritious morsels. Ultimately, these more sociable animals will be healthier, and will be more likely to have offspring.
Research has shown that the personality traits of fearfulness and friendliness seem to be genetically determined to a great degree. So the litters of the more socially-oriented wolves contain more pups that are comfortable around their human neighbours and are effectively tamer. Over successive generations, these settlement-dwelling wolves prosper and their numbers grow. Eventually, the tamest of them are comfortable openly foraging during the day.
The most sociable of the settlement-dwelling wolves have gained other advantages. Content in the presence of humans, they sleep nearer to the village and bear their puppies close by. This affords their vulnerable puppies additional safety, since most of the large predators that are a threat to wolves try to avoid concentrations of humans.
Wolves that are truly serene around humans find other additional benefits, such as huddling against human residences to obtain some of the heat leaking out during the cold months of winter. Over time, these small advantages add up and increase the survival chances of the most-sociable members of the group. Notice that it is the wolves themselves who, in trying to adapt to their environment, are genetically manipulating their own population.
The simple geographical separation between the more fearful wolves still living in the woods and the settlement-dwelling wolves makes it more likely that friendly and fearless animals will breed with other friendly and fearless animals. Over a number of generations, the original, wild-type wolves have changed.
What I have been calling settlement-dwelling wolves are really animals that have become genetically different from the original wild stock. The only human intervention might be actions to insure public safety that involve eliminating those now-rare individuals that are genetic throwbacks and display wolfish aggressive personality.
The traditional theory can now work because the starting point is no longer wild wolf pups, but rather puppies from this new species of settlement wolves, which are partially tamed already.
Since the settlement wolves live in such close proximity to humans, when they whelp, their litters are more likely to be found by humans. If the pups can be adopted at an older age, the burden of early care is considerably reduced. Because their personality no longer has the predisposition to fear and avoid humans, restraint and confinement is not needed and these adopted canines can more freely interact with humans.
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