What Makes Dogs Good at Certain Tasks?
Some dog breeds help humans hunt, others herd or protect livestock, and some excel as companion dogs. What makes them that way? Are their behaviors influenced by genes? Looking at over 4,000 purebred, mixed-breed and even semi-feral dogs, researchers have uncovered stunning new clues.
Analysis by Dr. Karen Shaw Becker
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STORY AT-A-GLANCE
- Researchers recently analyzed DNA samples from over 200 dog breeds, plus nearly 50,000 dog owner behavior assessment surveys to identify many of the genes associated with behavior in specific dog breeds
- The DNA analysis identified 10 major genetic lineages among hundreds of dog breeds: Terriers; Sheepdogs and Cattle dogs; Spitz and “Primitive Types”; Companion and Toys; Retrievers; Flushing dogs and Water dogs; Sighthounds; Pointing dogs; Scent Hounds and related breeds; and Dachshunds
- The research team focused in on livestock-herding dogs due to their easily defined breed-typical behaviors, i.e., their instinctive herding drive combined with unique motor patterns that move herds in complex ways
- The researchers believe that after three decades of trying to understand the genetics of why herding dogs herd, they’re finally beginning to unravel the mystery
While every member of every domestic dog breed and breed mix belongs to the species Canis familiaris, as most of us who have furry family members at home know, that’s often where the similarities end in terms of comparing the behavior of one breed to the next, and between members of the same breed.
Recently, researchers affiliated with the Dog Genome Project at the National Human Genome Research Institute analyzed DNA samples from over 200 dog breeds, plus nearly 50,000 pet parent surveys to identify many of the genes associated with behavior in specific dog breeds. The results of their study were published in December in the journal Cell.
"The largest, most successful genetic experiment that humans have ever done is the creation of 350 dog breeds," notes senior author Elaine Ostrander, founder of the Dog Genome Project. "We needed dogs to herd, we needed them to guard, we needed them to help us hunt, and our survival was intimately dependent on that."
To be successful at their jobs, like humans, dogs need to demonstrate specific behavioral traits, but finding the genes behind those behaviors continues to challenge scientists.
"The inherent complexity of canine population dynamics features varying degrees of selective pressure for aesthetic and morphological traits,” says lead study author Emily Dutrow, “some of which may be linked to behavioral traits, so pinpointing the genetics of canine behavior can be complicated."
10 Major Genetic Lineages Revealed
For the study, the researchers’ goal was to uncover the genetic drivers behind the behavior traits that make dogs good at specific tasks. Toward that end, they compiled whole genome data from over 4,000 purebred, mixed-breed, and semi-feral dogs, as well as wild canids.
Next, they employed computational tools to identify 10 major genetic lineages among hundreds of dog breeds, solely on the basis of DNA data:
- Terriers
- Sheepdogs and Cattle dogs
- Spitz and “Primitive Types”
- Companion and Toys
- Retrievers
- Flushing dogs and Water dogs
- Sighthounds
- Pointing dogs
- Scent Hounds and related breeds
- Dachshunds
The researchers discovered that each of the 10 lineages corresponded to a specific category of breeds that evolved, for example, to hunt by scent vs. sight, or to herd vs. protect livestock. This finding indicates that common sets of genes are responsible for behaviors among breeds well-suited for similar tasks.
“What is interesting about these groups is that they include dogs that work around sheep, for example, in quite different ways: Border collies and kelpies are active herding dogs who control the animals by giving ‘eye,’ while big livestock guarding dogs like the Great Pyrenees tend to move with the animals as escorts rather than actively herding them,” writes author Mark Derr in Psychology Today.
“Yet all three breeds are members of the Sheepdog and Cattle dog lineage. The key is to find the deep sources of their affinity for ‘herding.’ We are not dealing with a simple lockbox of traits but rather a whole suite of potential behaviors mixed and matched in virtually every dog.”
Dutrow believes this explains why both individual dogs and entire breeds have the ability to perform behaviors they aren’t necessarily “meant” to perform. “And, presumably, vice versa: the retriever who won’t swim,” adds Derr.
A Closer Look at Livestock-Herding Dogs
Next, the researchers surveyed pet owners to get a better understanding of the nature of the behaviors. Behavioral assessment surveys were sent to 46,000 owners of purebred dogs, and their responses allowed the research team to identify unique sets of behavioral tendencies among the 10 lineages.
One example: behaviors associated with increased prey drive were associated with the terrier lineage, which features breeds whose job throughout history involved catching and killing prey.
"Having established significant behavioral tendencies correlated with the major canine lineages, we then identified genetic drivers of these behaviors by performing a genome-wide association study on the DNA samples," says Dutrow.
"We were particularly interested in livestock-herding dogs, who display one of the most easily defined breed-typical behaviors, characterized by an instinctive herding drive coupled with unique motor patterns that move herds in complex ways."
The researchers were able to locate specific genes involved in brain wiring in herding dogs. They found that “variants near genes involved in axon guidance, a process that shapes brain circuitry, appeared highly enriched.” In addition, they discovered an enrichment for genes important for development of areas of the brain involved in social cognition and learned fear responses.
"When you get a certain input or stimulus, the degree to which that creates a reaction in different parts of the brain shapes how we behave," explains Ostrander. "So, if nerves within and between brain regions don't communicate in specific ways, then the behavior doesn't happen, and this is where axon-guidance genes come in to play."
Sheepdogs carry genetic variants that are often located near genes involved in ephrin signaling, which is an axon-guidance process involved in brain development and linked to behavior in other species (including humans). For example, the sheepdog gene EPHA5 has also been linked to human attention-deficit hyperactivity disorder (ADHD) and anxiety-like behaviors in other mammals.
The researchers believe these findings might help us better understand the high energy and hyper task-focused nature of sheepdogs.
"The same pathways involved in human neurodiversity are implicated in behavioral differences among dog lineages, indicating that the same genetic toolkit may be used in humans and dogs alike," says Dutrow.
Unraveling the Mystery at Last?
Per Ostrander:
"Emily's methodology allowed her to capture the different histories of dog breeding across the world, in one approach, one experiment, and without prior assumptions. After 30 years of trying to understand the genetics of why herding dogs herd, we're finally beginning to unravel the mystery."
From Derr’s perspective, while there is clearly a genetic component to specific behaviors or behaviors more common to specific breeds than others:
“… there is also a great deal of variation within those breeds and, in this case, lineages, and this variation is the result of a whole host of factors, many of which are not due to specific proteins, but rather to regulatory forces that nudge an individual’s genome in one direction or another.”
Derr further observes that:
“The extensive analysis to which Dutrow and her colleagues subjected their samples indicates that the entire base splitting into lineages came earlier in the dog’s development, which helps explain why some types of dogs seem more basic than others.”
Sources & References
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