Most dog owners firmly believe that their canine companions genuinely care when they return home—as evidenced by all the barking and tail-wagging. To test this assumption, researchers recently sought to quantify the relationship between a dog and its human owner. Their research produced physiological and behavioral evidence that the bond between a man and man’s best friend is the genuine article.
The effort to quantify the relationship between humans and their dogs has been undertaken by a number of different researchers at a number of different institutions. One particularly insightful study was recently published in the journal Behavioral Processes in which researchers examined the endocrinal and behavioral responses that dogs display after being reunited with a familiar human. To do this, 12 female beagles were first left by a human owner in a testing facility. After an interval of time, the human owner would return and either A.) initiate friendly physical and vocal contact with the dog, B.) initiate verbal contact only, or C.) completely ignore the dog. Blood samples were subsequently collected and analyzed.
The behavioral results were as one might expect. For the dogs that received both vocal and physical contact, the dogs reciprocated this contact, made their own vocalizations, and notably licked their lips more. Dogs that were only vocally recognized displayed a similar behavior but to a lesser extent. Dogs that were ignored initially displayed the same behavior, but would subsequently redirect their energy and affections towards the lab technician that was always stationed in the room to take the blood samples.
In terms of the physiological responses the dogs had to the different returning behaviors, analysis of the blood detected notable decreases in cortisol. Cortisol is a steroid hormone that is released from the adrenal glands in response to stress. Therefore, a lowering of cortisol levels would indicate that a returning human has an overall relaxing effect on their dog. This decline in cortisol levels was particularly marked in dogs that were physically and vocally affirmed. Furthermore, the return of a human was also shown to increase levels of oxytocin—a hormone which is associated with pair bonding. As with cortisol, the changes in oxytocin levels were most dramatic in the dogs that were physically and vocally recognized suggesting that dogs do care when you return.
In other research studies, it was found that dogs are especially discriminating between their owners, familiar people, and strangers. The researchers examined a dog’s behavioral responses to different situations like calling for food, walking away, playful interactions, and threatening challenges. In terms of being obedient, responding to a call for food, or being inhibited from getting food, dogs responded to their owners and familiar humans in the same way (although this did vary depending upon the dog’s level of training). By contrast, in tests that provoked fear or anxiety, the dogs showed marked differences in behavior between all three categories of humans.
Most dog owners do not need scientists to tell them that their dog cares when they return home. However ,in the meantime, scientists aim to continue trying to tease apart the bond between man and man’s best friend. In the future, it is hoped that this research can be applied to create more effective dog training programs and less stressful conditions for kennel dogs.
By Sarah Takushi