Dog lovers have long believed that a dog’s breed determines its temperament. However, a comprehensive study analyzing the behavior and ancestry of more than 18,000 dogs reveals that while ancestry does affect behavior, breed has much less of an impact on a dog’s personality than is commonly believed1.
“When you acquire a dog based on its breed, you get a dog with a specific appearance,” explains co-author Elinor Karlsson, a computational biologist at the University of Massachusetts Worcester. “However, as far as behavior is concerned, it’s a matter of chance.”
Form precedes function
This is partially because breeds are a very recent invention. Since domestic dogs originally emerged from wolves over 10,000 years ago, humans have influenced dogs’ appearance and behavior. But for the most of that period, these efforts concentrated on dogs’ working ability, such as how well they herded sheep, protected against danger, or towed sledges.
Breeds as we know them now — unique canines like beagles, pugs, and Labradors — are the result of recent evolutionary interference. Beginning roughly 200 years ago, dog aficionados in Victorian England began establishing breeds by intentionally selecting for aesthetically desirable canine characteristics.
This experimenting produced the breeds of today. Modern purebred dogs are defined by their appearance, but it is believed that their breed also influences their disposition. For instance, the American Kennel Club classifies pugs as “mischevious” and border collies as “affectionate.”
However, as Karlsson notes, “anyone who has owned eight dogs of the same breed can attest to their distinct personalities.” Karlsson and her colleagues contacted thousands of dog owners about their pets’ origins and habits, such as whether they had a tendency to eat grass and how likely they were to pursue toys, to gain a better understanding of how breed effects behavior. The researchers next sequenced the DNA of a subset of the survey dogs to determine whether there was a correlation between ancestry and behavior.
The study discovered that some features were more prevalent in specific breeds. Compared to a random dog, German shepherds were easier to guide, whereas beagles were more difficult. And the genetic tests of the authors found that mixed-breed dogs with a particular heritage were more prone to exhibit certain behaviors. Mutts descended from St. Bernards, for example, were more affectionate than those descended from Chesapeake Bay retrievers, who had a tendency for destroying doors.
Karlsson notes that, on average, breed accounted for only 9 percent of the difference in dog behavior, a statistic “far smaller than most people, including myself, would have anticipated.” This could have repercussions for how society regards “dangerous” dog breeds, says a comparative psychologist who was not involved in the study.
“We discuss breeds as if they are completely distinct,” he explains. In actuality, however, this is not the case.
According to genetic study, 11 areas of the genome are associated with specific behaviors. A predisposition to howl, for instance, has been linked to a region close to two genes whose human counterparts are involved in speaking. The strongest association was between a region of the dog’s genome associated with cognitive function in humans and an increased likelihood of becoming stuck behind objects.
According to Kelsey Witt, a population geneticist at Brown University in Providence, Rhode Island, these genetic features have survived considerably longer than breeds have existed. She states, “At first view, it seems odd that breed is not a reliable predictor of behavior.” It makes sense when you consider how recent breeds are, however.