Dogs and people are both highly social animals who crave gestures of warmth and approval from others. Whether dogs experience emotions the same way we do, or in some other way that looks similar but is actually foreign to our understanding, is a contentious issue. If dogs do have emotions like ours, though, the question of why they enjoy being petted by their significant humans is easy to answer -- it feels as good to them as a hug feels to us.
Emotionally, Are Dogs People Too?
In people, one specific region of the human brain, the caudate nucleus, is visibly activated by the anticipation of things we really enjoy, such as food, love and money, wrote neuroscientist Gregory Berns in the New York Times. Berns, author of “How Dogs Love Us: A Neuroscientist and His Adopted Dog Decode the Canine Brain,” wanted to find out whether the caudate area of dogs' brains reacted the same way. To that end, after training a dozen dogs to hold still while their heads were inside an MRI scanner, he created anticipation of two things that typically inspire displays of canine ecstasy: Food and the return of their owners. On the basis of "striking similarity" between canine and human responses within the caudate, Berns concluded that emotionally, "dogs have a level of sentience comparable to that of a human child."
Wolves, Dogs and Emotions
Stanley Coren, a professor of human psychology at the University of British Columbia, is widely known for the books he has written about dog behavior and psychology. One of his pet peeves is that "We are often led to wrong conclusions about the nature of dog behavior based upon observations of captive wolves," he wrote in Psychology Today magazine. Over the thousands of years people and dogs have lived together, our preference for animals who show affection means that we've selectively bred dogs to care for humans more than they care for other dogs -- something that would never happen among wolves, Coren theorizes. While some experts object to ascribing human-like emotions such as love to dogs, preferring terms such as "attachment" or "bonding," Coren himself has no problem with it.
Petting Reduces Stress in Dogs
The theory that dogs have stronger feelings for their significant humans than their fellow dogs is supported by a study published in The Journal of Comparative Psychology in March 1996. This experiment measured levels of the stress hormone cortisol in different situations in the blood of eight adult mixed-breed dogs. Dogs separated for the first time from littermates with whom they'd spent their entire lives seemed unconcerned. As long as they remained in familiar surroundings, their cortisol levels stayed the same. But when the same dogs were moved to unfamiliar surroundings, they became visibly agitated, and their cortisol levels shot up by 50 percent. However, when their human caretaker arrived on the scene and began petting them, cortisol levels quickly dropped back down to near normal levels.
The Effects of Petting: A Two-Way Street
The positive changes that occur in the body of a dog being petted appear to be much the same as those in the body of the person doing the petting, a 2004 study conducted by Missouri University's College of Veterinary Medicine suggests. Before, during and after petting sessions with dogs, blood pressure and levels of "feelgood" brain chemicals such as serotonin were measured in canine and human participants. In both, petting caused blood pressure to drop and serotonin levels to rise.
Dogs Who Don't Like Being Touched
Just like some people, some dogs don't enjoy being touched, warns the ASPCA. "Hand-shyness" is especially common among little dogs prone to being swept off their feet without warning by people whether they like it or not. Imagine how vulnerable you'd feel if every human you encountered was the size of a high-rise building. Dogs need to learn, preferably in puppyhood, that when human hands approach, good things such as treats, toys or cuddles, follow. Dog-lovers, especially children, must also understand that many dogs who like being petted by their humans don't welcome the touch of strangers -- so no reaching out to strange dogs unless owners give the go-ahead.