For centuries, police departments have favored German Shepherds, search-and-rescue teams have relied on Bloodhounds, and military units have trained Belgian Malinois. We’ve long believed these breeds were specially developed to excel at their jobs, thanks to unique skull shapes that enhanced their abilities. But new research suggests we’ve been wrong all along.
A new study published in Science Advances analyzed three-dimensional skull shapes from 117 canids, including 40 domestic dog breeds and 18 wild species like wolves and foxes. The surprising finding? Despite centuries of selective breeding that created dogs ranging from tiny Chihuahuas to massive Great Danes, there’s little evidence that these skull differences make breeds better at their traditional jobs.
“In the past 200 years, humans have created hundreds of dog breeds that look really different and are pretty specialized at some tasks like herding, protecting, and detecting odors,” explains Lindsay Waldrop, assistant professor of biological sciences at Chapman University, in a statement. “We have assumed that these dogs look different because they are structurally specialized at these tasks, but our study shows that, at least for their skulls, they are not specialized for tasks that involve the skull, such as biting tasks and scent work.”
The research team used advanced scanning technology to create detailed 3D models of dog skulls from museum collections. They mapped key points on each skull—like snout length, jaw structure, and cranial proportions—and compared these measurements across breeds. What they found challenges many common beliefs about working dogs.
“I was most surprised by the overall similarity we see in most of the dog skulls,” admits lead author Nicholas Hebron, who completed the work as a postdoctoral research associate at Chapman University. “Humans have done so much breeding work to alter the visual appearance of these animals that I honestly expected to see really marked groupings of some kind and we really didn’t see much of that.”
When researchers looked specifically at breeds used for scent detection or protection work, they found no distinct skull adaptations that would give these dogs an advantage, though scenting breeds showed some variation within a limited range. They calculated bite-force quotients for different skull types and found no significant differences between breeds historically used for bite work and other breeds of similar size.
This research directly challenges myths about certain breeds being more dangerous than others. “There are many news stories about dogs attacking people badly and often there are specific breeds that are targets of this reporting,” Waldrop notes. “Some people claim these dogs will bite harder than other dogs of the same size, or they have special features like ‘locking jaws’ that make them especially dangerous to people. Our study shows that this is simply not true.”
The only breeds that stood out as truly different were those with extremely short snouts, like Pugs and Bulldogs. These flat-faced breeds have skull shapes unlike any wild canids, suggesting these features came from human preferences rather than functional needs.
These results suggest that successful working dogs aren’t born with specialized equipment. Instead, they’re made through training, temperament, and determination. While we’ve bred dogs to look remarkably different from one another, their skull structures remain surprisingly similar. For organizations selecting working dogs, this means the perfect candidate might not come in the package they expect.