Why do dog breeds behave differently?

A dog’s behavior is not guaranteed by breed alone. According to one study, a dog’s breed explains about 9% of their overall behavior. Breed undoubtedly impacts aspects of a dog’s behavior—it’s part of the reason why we task Border Collies with herding and not Dalmatians. Behavior is complicated and fluid, and while a dog’s breed certainly plays a role in the development of canine personality, the ways our dogs actually behave is based a combination of factors. While there are aspects of a dog’s temperament that can seem hardwired, personality is a combination of nature and nurture. Factors that can impact the way a dog’s behavior develops include: Maternal influence, The amount and quality of early socialization, Environment, Ongoing socialization as the dog matures, Level of daily exercise, Training, Diet, Caregiver personality. A dog’s overall life experience is a better predictor of the way they’ll interact with the world around them.

While it is commonly acknowledged that different dog breeds exhibit varying temperaments and behaviors, scientific research in this area remains surprisingly sparse. The goal of the study, which will be conducted by Harvard University’s Canine Brains Project, is to investigate “behavioral traits in dogs from different breeds and lineages.” The description of the experiments to be conducted suggests that the study will focus primarily on personality traits like sociability, reactivity, communicativeness, and critical thinking ability rather than skills-based behaviors such as herding, tracking, or retrieving. There was a separate study, published in 2022, looking at how genetics might shape complex behavioral traits in dogs, which proposed that behaviors “perceived as characteristic of modern breeds” actually come from thousands of years of adaptation predating the formation of those breeds with “modern breeds distinguished primarily by aesthetic traits.” For “more heritable, more breed-differentiated traits, like biddability (responsiveness to direction and commands), knowing breed ancestry can make behavioral predictions somewhat more accurate” while for “less heritable, less breed-differentiated traits, like agonistic threshold (how easily a dog is provoked by frightening or uncomfortable stimuli), breed is almost uninformative.” In my experience, it’s possible to make some guesses about future behavior based on the breed of the dog, the temperament of the parents, the skills that run in the genetic line, and so on—that’s what selective breeding is all about—but there are still so many unknowns that go into how a specific dog acts and what she might need.

Now, in the most comprehensive study of its kind to date, scientists have shown that such distinct breed traits are actually rooted in a dog's genes. The team matched up these behavioral data for each breed with genetic data about breeds from different sets of dogs. In all, the team identified 131 places in a dog's DNA that may help shape 14 key personality traits. Together, these DNA regions explain about 15% of a dog breed's personality, with each exerting only a small effect. Trainability, chasing, and a tendency to be aggressive toward strangers were the most highly heritable traits, the scientists report. The locations of these DNA hot spots make sense: Some are within or close to genes tied to aggression in humans, for example, whereas DNA associated with the dog's level of trainability is found in genes that in humans are associated with intelligence and information processing. The findings suggest behavior is guided by the same genes in many species, MacLean says. Because the genetic and behavioral data come from different sets of dogs, the work cannot link a breed's specific behavioral tendencies to any one gene.