It turns out that we may be stereotyping dogs incorrectly.
Modern breeds are shaped around aesthetics: the bat-like ears of chihuahuas, the curly coat of poodles, the hot dog shape of dachshunds. But breeds are also often associated with certain behaviors. For example, the American Kennel Club describes border collies as “affectionate, smart, energetic” and beagles as “friendly, curious, cheerful.”
Now, genetic information from more than 2,000 dogs, combined with self-reported surveys of dog owners, indicates that the dog’s breed is a poor predictor of its behavior. On average, breed accounts for just 9 percent of behavioral differences between individual dogs, researchers report April 28 Science.
“Everyone assumed the breed was predictive of dog behavior,” geneticist Elinor Karlsson of the University of Massachusetts’s Chan Medical School in Worcester said in a news conference April 26. But “that was never really particularly well asked.”
Geneticists had asked the question in various ways before. A 2019 study looked at whether genetics could explain the collective variation between breeds and found that genes could explain some of the differences between, say, poodles and Chihuahuas (SN: 1-10-19). But Karlsson and her colleagues wanted to know how much breed can predict variation in the behavior of individual dogs.
To study variation at the individual level, the team needed genetic and behavioral data from many dogs. So they developed Darwin’s Ark, an open-source database where more than 18,000 pet owners responded to surveys about their dog’s traits and behavior. The survey asked more than 100 questions about observable behavior, which the researchers grouped into eight “behavioral factors,” including human sociability (how comfortable a dog is around people) and responsiveness (how does he respond to commands).
The researchers also collected genetic data from 2,155 purebred and mixed dogs, including 1,715 Darwin’s Ark dogs whose owners sent in canine saliva swabs. The inclusion of mixed breed dogs, or mutts, sheds light on how ancestry influences behavior, while removing the purebred stereotypes that can affect the way the dog is treated — and thus behaves.
Studying mutts also makes it easier to separate traits, says Kathleen Morrill, a geneticist in Karlsson’s lab. “And that means, on an individual basis, you have a better chance of mapping a gene that actually relates to the question you’re asking.”
Then the team combined the genetic and research data for the individual dogs to identify genes associated with certain traits. The new study revealed that the most heritable behavioral factor for dogs is human sociability, and that motor patterns — such as howling and retrieving — are generally more heritable than other behaviors.
That makes sense, Kathryn Lord, an evolutionary canine biologist in Karlsson’s lab, said during the briefing. Before modern breeding began in the last few hundred years, dogs were selected for the functional roles they could provide, such as hunting or herding (SN: 26/4/17). Today, these selections still occur in breed groups. For example, sheepdogs are on average more biddable and interested in toys. It also follows that, within breed groups, individual breeds are more likely to exhibit certain motor patterns: unsurprisingly, retrievers are more likely to fetch.
But while race was associated with certain behaviors, it was not a reliable predictor of individual behavior. Although retrievers are less likely to cry, some owners reported that their retrievers howled frequently; greyhounds rarely bury toys, except some do.
The study confirms what people have observed: Dog breeds vary in behavior on average, but there is a lot of variation within breeds, says Adam Boyko, a canine geneticist at Cornell University who was not involved in the study.
Surprisingly, size had even less effect — as in, virtually none — on a person’s behavior, despite the yappiness commonly associated with small dogs. Boyko points out that small dogs often behave worse than large dogs, but rather than having this built into their genetics, “I think we generally tolerate bad behavior more in small dogs than in large dogs.”
As a dog trainer, Curtis Kelley of Pet Parent Allies in Philadelphia says he meets a dog where he is. “Dogs are just as individual as humans,” he says. Race provides a loose guideline for what kind of behavior to expect, “but it’s certainly not a hard and fast rule.”
If anyone wants to buy a dog, he says, they shouldn’t put too much stock in the dog’s breed. Even within a litter, dogs can exhibit very different personalities. “A puppy will show you who they are when they are eight weeks old,” Kelley says. “It’s just our job to believe them.”