Why Are Dogs So Loyal?

There's a scientific explanation to what makes them "man's best friend"

Back view of a boy and a dog sitting in front of a house
Daniel Grill / Getty Images

Any dog owner will tell you that there’s something indescribable and unique about their loyal companions. Dogs wait for their humans patiently by the door when they leave, act like they’ve been given the world when their dinner bowls are filled, and express a sense of devotion that is rare in many other pets. Where does this trait, the trait that makes dogs “man’s best friend,” come from? Why are dogs so innately loyal? The obvious explanation would be that their owners provide them with food and shelter, but the deeper answer actually comes down to science.

It’s no secret that domesticated dogs are descendants of wolves. Even today, modern dogs continue to share similar genes to wolves that live in the wild. The idea of “the loyal dog” is both a cultural and biological construct, as humans have created the dog over years of selective breeding and domestication to be this way. Essentially, humans picked and chose the wolf characteristics that would best serve their own benefit, transforming a wolf’s hierarchical structure and social bond to their packs into obedience and loyalty to humans.

Selective Breeding

Throughout history, long-term domestication has resulted in hundreds of different dog breeds designed to fulfil specialized functions in society, many with significant behavioral differences. Early humans likely participated in selective breeding without even knowing they were doing so, by killing off the dogs who attacked or bit a member of their family or community. Additionally, dogs who were naturally gifted as loyal hunters would have been better cared for, upping the chances of successful and repeated reproduction. Dogs that contributed to society were kept for longer, while aggressive or unskilled dogs weren’t. And, as humans promoted dogs with tame or friendly characteristics, physical attributes began to change as well.

The early domesticated dogs intelligent enough to associate their owners with things like food and shelter in exchange for obedience (think: “don’t bite the hand that feeds you”) were more likely to survive longer. In a reliance comparison between dogs and cats, for example, studies show that dogs attempt tasks before looking at their owners while cats do not.

While it may have started with a simple exchange of food and shelter for animal-assisted guarding or hunting, humans eventually began to favor dogs that were more docile and sociable. As humans evolved to hunt less and moved on to more secure lifestyles, the domestication process eventually began to encourage companionship.

Pack Behavior

Dogs, like their wolf ancestors, are pack animals at their core. In order to survive in the wild, members of a pack have to be trusting and cooperative. A wolf leader, or alpha, is in charge until it becomes too sick or old to perform at its highest abilities and is eventually challenged by a stronger wolf for the betterment of the entire pack. This suggests that wolves are motivated by the good of the group rather than pure loyalty to its leader. This is exactly what a 2014 study in Vienna found when researchers examined lab-raised dog and wolf packs, concluding that the relationship between dogs and humans is hierarchical (with their owner at the top) rather than cooperative. As wolves were slowly domesticated into modern dogs, the study suggests, they were bred for their loyalty, dependance on human masters, and ability to follow orders.

Social Bonding

Oxytocin, the peptide hormone released when people hug, snuggle, or bond socially, also has a part to play. Gaze-mediated bonding, as well as petting and talking, increases oxytocin levels in both humans and dogs. This is a human-like mode of communication, since wolves rarely make eye contact with their handlers, meaning that the fact that you and your dog like to lock eyes is a trait likely picked up during the domestication process. Oxytocin is linked to feelings of attachment and confidence, which in turn facilitate the establishment of loyalty and love in emotional relationships. The fact that oxytocin increases in both humans and dogs — but not wolves — while engaging in eye contact and communicating social attachments may have supported the evolution of human-dog bonding.

Are Some Breeds More Loyal Than Others? 

The domestic dog, or Canis lupus familiaris, is the first and only large carnivore ever to have been domesticated by humans. Mostly within the last 200 years or so, dogs have undergone a rapid change characterized by maintaining breeds through selective breeding imposed by humans. Compared to other wild and domestic species, modern dogs display incomparable genetic diversity between breeds, from a 1-pound poodle to a 200-pound mastiff.

We’ve all heard stories of individual dogs known for fierce loyalty, like Hachiko, the Japanese Akita who waited for his master every day by the Shibuya Station in Tokyo even after he passed away at work. A 2018 study on the genomic make-up of the Czechoslovakian wolfdog found that a common German shepherd crossed with a wild wolf has the same tameness and loyalty to its master as a fully domesticated dog.

There isn’t much scientific evidence of certain breeds being more loyal than others, though one could certainly argue that dogs bred for specific jobs like hunting and herding would have a higher chance of staying loyal to their owners. Breeds that are known for specific tasks may not check all the boxes depending on qualities preferred by the owner. The dependency on human guidance desired in companion dogs may get in the way of a rescue dog’s ability to function successfully in situations when its handler isn’t around, for example. There is a “nature vs. nurture” aspect to consider as well. It isn’t all about genes, though they do play a critical role, but a dog’s individual environment and history can also greatly affect its lifetime behavior.

View Article Sources
  1. DeMello, Margo, and Jeff Hayes. Speaking for Animals: Animal Autobiographical Writing. Routledge, 2015.

  2. Zhang, Zhe, et al. “Deciphering the Puzzles of Dog Domestication.” Zoological Research, vol. 41, no. 2, Mar. 2020, pp. 97–104., doi:10.24272/j.issn.2095-8137.2020.002

  3. R Udell, Monique A., and C.D.L. Wynne. “A Review of Domestic Dogs' (Canis Familiaris) Human-Like Behaviors: Or Why Behavior Analysts Should Stop Worrying and Love Their Dogs.” Journal of the Experimental Analysis of Behavior, vol. 89, no. 2, Mar. 2008, pp. 247–261., doi:10.1901/jeab.2008.89-247

  4. Range, Friederike, et al. “Wolves Lead and Dogs Follow, but They Both Cooperate with Humans.” Scientific Reports, vol. 9, no. 1, 7 Mar. 2019, doi:10.1038/s41598-019-40468-y

  5. Nagasawa, Miho, et al. “Oxytocin-Gaze Positive Loop and the Coevolution of Human-Dog Bonds.” Science, vol. 348, no. 6232, pp. 333–336., doi:10.1126/science.1261022

  6. Caniglia, Romolo, et al. “Wolf Outside, Dog inside? The Genomic Make-up of the Czechoslovakian Wolfdog.” BMC Genomics, vol. 19, no. 1, 13 July 2018, doi:10.1186/s12864-018-4916-2