Dogs go way back. In fact, it's been more than 15,000 years since dogs diverged from wolves, and it was humans who played a major role in their creation. We domesticated dogs and relied on them to help us survive. This history made dogs unique among animals and allowed them to form strong bonds with people.

Mark Petersen, founder of Utah's Bank of the West Soldier Hollow Classic sheep herding competition says there's a monument in a small town in Montana to a dog belonging to a shepherd that illustrates this human dog bond.

"He died. His family was back east when he died. They shipped his body back east. The dog followed the casket to the train station, watched it drive away and then for the next five years until it died of old age. The dog never left the train station, met every train, would not allow anyone to come and comfort it or be with it. But it just waited every day for the train to be there."

So how did dogs evolve from a wild predator into man's helper and companion? Robert Wayne, professor of ecology and evolution at UCLA, says at first wolves probably started hanging around humans because of our trash.

"Humans provided carcasses and wolves provided early warning systems and eventually may have helped in the hunt. That mutualism grew with time so eventually wolves became dogs."

Wayne says some wolves, the ones that tolerated humans, were more likely to follow them around. These wolves became tamer over time to the point where they were eventually domesticated.

"The barriers of mistrust have been broken down between dogs and humans. And dogs are very able to engage with us in a very personal way."

Because dog domestication happened thousands of years ago this theory is difficult to prove. But an experiment in the 1950s showed that domestication can happen fast. A group of silver foxes in Siberia were selected for tameness by only allowing the tamest animals to mate.

"A man named Belyaev decided to re-evolve domestication using foxes there," says Gordon Lark, professor emeritus in biology at the University of Utah. "And the surprising thing was that within ten years he was very successful. He had foxes that were wagging their tails that would get all excited when a person came around and wanted to be petted."

Surprisingly, Lark says as the foxes became tamer they developed floppy ears, began to bark, and the color of their coats changed. Similar physical changes happened as dogs evolved from wolves. So as a behavior - tameness - evolved, so did the physical appearance, suggesting certain genes are responsible for both.

Researchers are now trying to track down these domestication genes. To find them, UCLA's Robert Wayne and colleagues compared regions between dog and wolf DNA looking for differences between the two.

"In our first kind of scan where we looked at 48,000 markers across the dog and wolf genomes, we found a number of interesting candidates that affect behavior," says Wayne.

Domestication was only the first part of the dog's story. Once they were tamed, humans molded dogs into workers that could do specific jobs well. For example, herding sheep, hunting birds, guarding property or livestock.

"Different dog breeds have been developed because of specific behavior traits," says Elaine Ostrander with the National Human Genome Research Institute. "So herding dogs herd, draft dogs pull, and pointers point. And a lot of this comes from very strong genetics. It would be very hard, if not impossible, to teach a toy poodle to herd a flock of sheep."

Border collies are an example of a dog breed specialized for their behavior. They were bred in the 1800s to herd livestock in the border regions between Scotland and England. Border collie enthusiast Mark Petersen says they were bred for their intelligence and their innate instinct to control and herd moving objects.

"The handlers talk to these dogs, usually through whistles when they're far away and through voice commands when they're up close," says Petersen. "And you ask them, does that dog ever disobey you up there. And the answer is of course they do. ‘They're right there, they know better to do then I might think what needs to be done. I have to trust that if they disobey me that's because I was wrong.’ Now that is a really complex concept."

Tom Wilson and his dog Sly participated in this years' Soldier Hollow competition. He says what the dogs do is 90% innate ability and 10% handler.

"They've got the instinct in them. So we don't make them work, they work and we just trick them into doing what we want them to do in a way. They would rather work than eat sometimes," saya Wilson

And what can dogs teach us about our own behaviors? Dog geneticist Elaine Ostrander says after 20 years of study, the genetic tools have now been created that will allow researchers to finally begin addressing this difficult question.

"You know when we look at dogs we see so much of ourselves," says Ostrander. We see empathy, we see loyalty, we see companionship. We just see so many things that we value as a society. And so we have this urge to understand the vocabulary of behavior in dogs I think in the hopes that it will help us understand the lexicon of human behavior as well."

Throughout their history dogs have been partners with humans and now we are closer than ever to understanding how that came to be.

This story originally aired 9/26/09