With our big eyes, wagging tails, and enthusiastic greetings, it is easy to see why humans fall in love with dogs. But is the feeling mutual? In honor of Valentine’s Day, we bring you scientific proof that dogs are love. The following are four studies conducted between 2015 and 2017 that show there is neurological and genetic evidence as to why dogs are so loving and bond easily with humans.
The Nose Knows: Let’s begin by examining the results of the 2014 study, “Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors,” published in Science Direct, on January 2015. By scanning dogs’ brains, neuroscientist Gregory Berns, found that dogs’ brains light up positively when we smell the familiar scent of our owner, as oppose to a random person or dog. Specifically Berns and his associates trained to dogs to lay still during an MRI for up to 30 second intervals. They then exposed the dogs to five scents: self, familiar human, strange human, familiar dog, strange dog, while monitoring a part of dogs’ brain called the caudate nucleus, which helps coordinate our neural reward system.
What they found was although the olfactory bulb would respond by some degree to all scents, the caudate significantly reacted to the smell of a familiar human. It is important to note that the familiar human was not the one handling the dog during the experiment, demonstrating that the person did not have to be present to get that neurological response. Bern concluded, “The caudate activation suggested that not only did the dogs discriminate that scent from the others, they had a positive association with it.” Further research needs to be done to determine that the dogs just aren’t associating the smell of their owners with dinner, but there is evidence that there is a connection to being with a specific person that triggers a positive response in dogs’ brains.
Gaze into My Eyes: Another example of a neurological response and the connection to smell is the 2015 study “Oxytocin-gaze positive loop and the coevolution of human-dog bonds,” published in Science on April 17, 2015. It is a well known fact that when humans gaze into each other’s eyes they release the hormone oxytocin, which is often referred to as the “love hormone.” What Miho Nagasawa and his colleagues found was that something similar happens when humans look into the eyes of their dogs. The dogs in turn can smell their humans’ oxytocin levels rising, which in turn raised their levels of the hormone, resulting in a “oxytocin-gaze positive loop.” This may help explain the deep bond between humans and their dogs, or at least why we stare into each others’ eyes a lot.
When I see You Smile: This bond between dogs and humans goes beyond the sense of smell though, as demonstrated in another 2015 study, “Dogs recognize dog and human emotions,” published by Royal Society Publishing in Biology Letters, in January 2016. In this study the researchers posted pictures of happy and sad human faces in front of each test dog, and played a happy or angry human voice in an unfamiliar language. The dogs responded by staring at the image that most closely matched the emotion of the sound. Thus showing that dogs can discriminate human facial expressions and emotional sounds.
Natalia Albuquerque and associates concluded, “These results show that domestic dogs can obtain dog and human emotional information from both auditory and visual inputs, and integrate them into a coherent perception of emotion. Therefore, it is likely that dogs possess at least the mental prototypes for emotional categorization (positive versus negative affect) and can recognize the emotional content of these expressions. Moreover, dogs performed in this way without any training or familiarization with the models, suggesting that these emotional signals are intrinsically important.” So yes, dogs do know when humans are happy or sad. Although I should note, in this study dogs responded more to towards the stimulus of their fellow dog, as oppose to the humans.
Indiscriminate Friendliness: Finally, in the 2017 study, “Structural variants in genes associated with human Williams-Beuren syndrome underlie stereotypical hypersociability in domestic dogs,” published in Science Advances, July 19, 2017, researchers identified a gene in dogs often associated with a genetic disorder of indiscriminate friendliness in humans. Bridgett vonHoldt and her fellow researchers concluded, “Empirical demonstrations remain robust that dogs display exaggerated gregariousness, referred to as hypersociability, which is a heightened propensity to initiate social contact that is often extended to members of another species,” due to the presence of this gene.
Therefore, as Clive Wynne, a psychologist at Arizona State University who specializes in dog behavior concluded, dogs have “an abnormal willingness to form strong emotional bonds with almost anything that crosses their path.” He continued, “And they maintain this throughout life. Above and beyond that they have a willingness and an interest to interact with strangers.” Or to put it in even more simpler terms to quote Dug the dog from the movie Up, “I have just met you, and I love you!”
So there you have it folks, based on neurological and genetic evidence, us dogs really do love you on Valentine’s Day, and every day!
