One of the main reasons we like dogs so much is that they like us too. Most dogs greet us with wagging tails, eager for a little petting and some human companionship.

If you met a wolf, on the other hand, chances are it wouldn't be so sociable. Dogs evolved from wolves thousands of years ago, but along the way, a genetic change occurred that could explain their difference in congeniality.

That's what researchers at Oregon State University discovered when comparing domesticated dogs with wolves and their social interactions with humans. Their findings were published recently in the journal Scientific Advances.

Until now, scientists didn't really understand what happened genetically through the years that allowed dogs to thrive in human environments, said Monique Udell, an animal scientist at Oregon State and lead co-author of the study.

“It was once thought that during domestication dogs had evolved an advanced form of social cognition that wolves lacked," Udell said in a statement. "This new evidence would suggest that dogs instead have a genetic condition that can lead to an exaggerated motivation to seek social contact compared to wolves.”

Basically, genes that made dogs particularly outgoing and gregarious were selected for as dogs evolved from their wolf ancestors.

Eventually wolf descendants became friendlier and friendlier, which likely paved the way for dog domestication.

Testing dogs and wolves

A captive wolf sniffs an unfamiliar person during a sociability test. A captive wolf sniffs an unfamiliar person during a sociability test. (Photo: Monty Sloan/Oregon State University/flickr)

For the study, researchers tested the behavior of 18 domestic dogs and 10 gray wolves that live in captivity. They evaluated the animals using several problem-solving and sociability tasks.

For the first test, the animals were given a box containing a sausage while a person was present. The dogs were more likely to look at the person instead of trying to open the box. The wolves were more likely to open the box, even if a person was there.

For the second test, a person sat down in a marked circle. In the first part of the test, the person called the animal by name and encouraged contact but stayed in the circle. In the second part of the test, the person sat quietly and ignored the animal by looking at the floor.

Both the dogs and the wolves quickly approached the person, but the wolves wandered away, losing interest after just a few seconds. The dogs, however, were much friendlier. They stayed longer with both people they knew and those they didn't.

Researchers collected blood samples from the animals for genetic testing.

“We’ve done a lot of research that shows that wolves and dogs can perform equally well on social cognition tasks,” Udell said. “Where the real difference seems to lie is the dog’s persistent gazing at people and a desire to seek prolonged proximity to people, past the point where you expect an adult animal to engage in this behavior.”

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.