Timber, a mother of some of the pups at Wolf Park, a 65-acre zoo and research facility in Battle Ground, Indiana. — ANDREW SPEAR/The New York Times
In the beginning, there was only Tasha. Twenty years ago, the purebred boxer became the first domestic dog to have her genome sequenced, ushering in a new era in canine genetics.
“Once that happened, everything broke open,” said Elaine Ostrander, a canine genomics expert at the National Human Genome Research Institute who was on the team that sequenced Tasha.
In the two decades since, scientists have sequenced the genomes of thousands of dogs – canines of all shapes and sizes, living all over the world and dating back thousands of years.
Researchers are now comparing these genomes and cross-referencing them with other records, like behavioural surveys completed by eager pet owners and pedigreed breeding records dating back generations. (“You know, who begot who,” said Lachie Scarsbrook, a paleogenomicist at the University of Oxford.)
These enormous data sets are allowing scientists to ask a wide variety of sophisticated questions about dogs, humans and our long-standing, still-evolving relationship.
A new collection of eight canine genomics papers, published by the Proceedings Of The National Academy Of Sciences, is a case in point.
“We’re now answering questions that we couldn’t even begin to think to ask 20 years ago,” said Greger Larson, a paleogenomicist at the University of Oxford. Not all of the answers are simple, and scientists still have plenty to learn, he added.
“But my God, have we made a ton of progress,” he said.
New studies of canine genetics shed light on the diversity of dogs and our longstanding, still-evolving relationship to them. — CALLA KESSLER/The New York Times
The new collection was edited by Ostrander; Larson; Kathryn Lord, an evolutionary biologist at the UMass Chan Medical School and the Broad Institute; and William Murphy, a comparative genomicist at Texas A&M University. Here are some of the findings:
Disappearing diversity in German Shepherds
Many modern dog breeds are highly inbred, leaving them susceptible to an assortment of serious health problems.But questions remain about exactly when and how genetic diversity disappeared from purebred populations.
One possibility is that the drop in genetic diversity dates back primarily to the 19th century, when many modern breeds were created from a small number of founding dogs. Although this phenomenon did appear to occur in German shepherds, the most significant drops in diversity didn’t come until the second half of the 20th century, according to one of the new papers, whose authors included Scarsbrook, Larson and Ostrander.
What happened? The population of German shepherds plummeted during World War II. Then, after the war, breeders relied heavily on a handful of “popular sires,” or male dogs with especially desirable characteristics. Many of the German shepherds in the United States, for instance, can trace their ancestry back to a dog known as “Lance of Fran-Jo,” whose sloping back is now common in the breed.
The problem with dog DNA tests for behaviour
Some dog DNA tests promise to give curious owners new insights into their pets’ temperaments and behaviour, revealing whether their dogs have genetic variants that have been associated with friendliness or fearfulness, for example.
But in a new study of 151 of the variants that have been linked to canine behaviour, scientists found that not a single one accurately predicted the behaviour of individual dogs.
The studies that originally identified these variants, the researchers concluded, were fundamentally flawed. Instead of assessing the behaviours of individual dogs, these studies used breed as a proxy for behaviour.To identify the underpinnings of friendliness, for instance, researchers looked for genetic variants that were more common in friendly breeds than in less amiable ones.
In the new study, researchers used data from Darwin’s Ark, a large community science project of pet dogs, to test these associations in thousands of individual dogs. Were dogs with a purported “fear” variant, for instance, actually more skittish than those without it? “We found zero associations with behaviour,” said Lord, who was an author of the study.
In many cases, variants that scientists had previously linked to canine behaviour were actually associated with some of the highly heritable physical traits that vary between breeds.For example, a variant that had previously been linked to fear and aggression turned out to be associated with leg length and height.
Shared behavioural genes in dogs and people
Lord’s findings don’t mean that there aren’t genes related to canine behaviour. But the best way to identify those genes, she said, is to compile and analyze large data sets on the genes and behaviours of individual dogs.
Another team of scientists did just that in a separate study, analysing genetic and behavioural data on more than 1,000 dogs enrolled in the Golden Retriever Lifetime Study.The researchers ultimately identified 18 genes that might be related to various aspects of temperament and behaviour, including trainability, fear of strangers and aggression toward other dogs.
Two-thirds of these genes, they found, had also been associated with cognitive or neuropsychological traits in humans.For instance, a gene that was associated with nonsocial fear in dogs – that is, fear of things like fireworks and vacuums – had previously been linked to things like mood swings, anxiety, irritability and sensitivity in people.
“Maybe what we’re picking up here is that there is a biological driver for a tendency toward finding life pretty stressful,” said Dr Eleanor Raffan, a veterinarian and geneticist at the University of Cambridge and an author of the study.“It’s not that we can say it’s the exactly the same biology going on, but it perhaps gives us a bit of a clue as to why dogs are displaying these signs of being fearful when they’re out there in the world.”
Several genes linked to canine trainability had been associated with intelligence in humans – but also with traits like anxiety, sensitivity and a tendency to worry.Although the idea remains speculative, one possibility is that what makes some dogs highly trainable is not only that they are smart but also that they are “really afraid of failure,” Raffan said.
The findings do not mean that dog behaviours map perfectly onto humans, of course, and there are many non-genetic factors that influence behavioural and psychological traits.But the findings suggest that there might be some “really fundamental biology” that affects the way both species interact with the world, Raffan said. – ©2026 The New York Times Company
