WASHINGTON, USA – These are well-known stereotypes: Rottweilers and Pit Bulls are aggressive, while Labradors and Golden Retrievers are very friendly.
But a genetic study published Thursday in the journal Science involving more than 2,000 dogs associated with 200,000 survey responses from owners demonstrates that widespread assumptions are largely unfounded.
Certainly, many behavioral traits can be inherited – but the modern concept of breed offers only partial predictive value for most types of behavior – and almost none on a dog’s affection or, conversely, on his quickness to anger.
“While genetics plays a role in any dog’s personality, a specific breed of dog is not a good predictor of these traits,” said lead author Elinor Karlsson, of UMass Chan and the Broad Institute. from MIT and Harvard.
“What we found is that the defining criteria of a golden retriever are its physical characteristics – the shape of its ears, the color and quality of its fur, its size – not whether it is friendly.” , she added.
Lead author Kathleen Morrill explained that understanding the relationship between race and behavior could be the first step in understanding the genes responsible for psychiatric disorders in humans, such as obsessive disorder.
“While we can’t really ask a dog themselves about their problems, thoughts or anxieties, we do know that dogs lead emotionally rich lives and suffer from disorders that show up in their behavior,” he said. she said during a press call.
Implications for legislation
The team sequenced the DNA of 2,155 purebred and mixed-breed dogs to look for common genetic variations that might predict behavior, and combined that information with surveys from 18,385 pet owner surveys. Darwin’s Ark.
The site is an open-source database of canine traits and behaviors reported by owners.
Because existing stereotypes are so powerful, the team designed their questionnaires to take homeowner biases into account.
They established standard definitions for reporting traits such as submissiveness (the dog’s response to human direction), dog-human sociability (how comfortable dogs are around people, including strangers), and toy-directed motor patterns (how interested they are in toys).
Physical and aesthetic traits were also studied.
In all, Karlsson and Morrill found 11 locations on the dog’s genome associated with behavioral differences, including submission, retrieval, pointing at a target, and howling.
Of these behaviors, breed played some role – for example, beagles and bloodhounds tend to howl more, border collies are rideable, and Shiba Inus are much less so.
However, there were always exceptions to the rule.
For example, although Labs had the lowest propensity to scream, eight percent still did. While 90% of greyhounds did not bury their toys, 3% did so frequently.
“When we looked at this factor, which we called the agonistic threshold, which included many questions about how dogs react aggressively, we didn’t see an effect of racial ancestry,” Karlsson added.
Overall, race explained only 9% of behavioral variation, with age being a better predictor of certain traits, such as playing with toys. Physical traits, however, were five times more likely to be predicted by race than behavior.
The idea runs counter to widely held assumptions that have informed the legislation. For example, Britain has banned pit bull terriers, as have many American cities.
Prior to the 1800s, dogs were primarily bred for functional roles such as hunting, guarding and herding, the team said in their paper.
“By contrast, the modern dog breed, which emphasizes confirmation of physical ideals and purity of lineage, is a Victorian invention,” they wrote.
Modern races carry genetic variations from their ancient predecessors, but not at the same frequencies, which explains the divergence in behavior within races.
The next steps, Morill said, would be to dig deeper into compulsive behaviors in dogs and the links to human obsessive-compulsive disorder.
An intriguing finding was that canine sociability towards humans was “incredibly inherited in dogs”, although it was not dependent on breed.
The team found a location in the dog’s DNA that could explain 4% of the differences in sociability between individuals – and this location corresponds to an area of the human genome responsible for forming long-term memory.
“It could be that understanding human sociability in dogs helps us understand how brains develop and learn, so we’re only scratching the surface,” Morill said.