Dogs' loyalty to humans stems from the shared past of the two species. After the domestication of the dog, the species and humans began to change together. Consequently, the two species developed an understanding that no other species, including higher order primates, shares with humans. Research into the bond between humans and dogs has found a number of behaviors that developed from and continue to grow the loyalty between dogs and humans.
Researchers originally believed domestic dogs separated from their wolf ancestors after they began living among humans. However, more recent studies suggest otherwise. Studies of the mitochondrial DNA of wolves and dogs show the two split about 135,000 years ago. Archaeological evidence, such as the discovery of buried dog bones near human settlements, suggests dogs and humans began sharing their lives only about 13,000 years ago. Although more research on the subject is needed, these studies show dogs were already a separate species when they first encountered humans.
Dog Loyalty and Pack Behavior
According to Merriam-Webster, loyalty means having a faithful allegiance to another person or institution. Some trainers argue dog loyalty stems from their pack behavior. Because dogs want to bond with a group, they instinctually show loyalty to those who are or who could be part of their pack. Allegiance among members of the pack would be crucial to its success. Therefore, early dogs who wanted to form a pack with early humans would have expressed loyalty to those humans to make the pack work effectively for both species.
Communication and Loyalty
Throughout their shared past, dogs have developed better ways of communicating with humans. Research argues that dogs are more human-like in their behaviors than any other animal, including primates. For example, a study found that dogs can express empathy to humans. In the study, the dog's companion or a stranger was crying in the same room with the dog. The dog attempted to comfort her companion but also the stranger. In other studies, researchers have found dogs can understand verbal and physical gestures from humans, as well as their facial expressions. Humans also can accurately interpret the meaning of dog barks, according to other studies. This ability to communicate with one another – something not found among other species – developed from the species reliance on one another and continues to increase their loyalty to one another.
Dogs as Equals
Dog loyalty also may stem from the fact that dogs view themselves as our equals – not as a separate species. According to Dr. Stanley Coren, studies have shown that dogs can tell the difference between selfish and generous humans. In the study, two humans with treats were approached by a third human. Human A refused to give the third person a treat and treated them coldly. Human B was kind and gave the other human a treat. When the dog was allowed to mingle with the humans, he went to the human who gave the treats. Dr. Coren believes this preference indicates dogs expect humans to treat them the same way they treat other humans.
Cesar's Way: The Loyalty of Dogs
Psychology Today: Dogs Recognize Generous Versus Selfish People
Psychology Today: Canine Empathy: Your Dog Really Does Care If You Are Unhappy
The Atlantic: The Prehistoric Dog
Journal of the Experimental Analysis of Behavior: A Review of Domestic Dogs' (Canis Familiaris) Human-Like Behaviors: Or Why Behavior Analysts Should Stop Worrying and Love Their Dogs
NPR: Canine Mystery: How Dogs Became Man's Best Friend
NOVA: Dog Decoded Transcript
Merriam Webster: Loyal