You know that look your dog gives you when he wants something—whether it be food, a walk, a toy, or maybe just attention. His eyes get bigger and droopier, and he looks so sad that you just have to acquiesce to his wordless request. But how does he DO that? It turns out science can tell us a lot more than we ever thought we’d learn about puppy-dog eyes.
The answer, it seems, lies in two muscles, called the retractor anguli oculi lateralis muscle and the levator anguli oculi medialis muscle (RAOL and LAOM, respectively). These two muscles connect the ring of muscle around the dog’s eye to either end of his eyebrow. By using these muscles, he can tilt his eyebrows so the inner corner is lifted, giving him that wide-eyed sad look that we all know and love.
Interestingly enough, dogs seem to use this eyebrow maneuver mostly when humans are paying attention to them. They move their eyebrows considerably less after they’ve been given food or while they’re being ignored by humans. Believing that the RAOL and LAOM muscles might be used primarily for communicating with humans, researchers from the University of Portsmouth’s Dog Cognition Centre decided to take a closer look into these muscles and into whether different canine species have and use them.
What they found is that wolves completely lack RAOL and LAOM muscles. In the four gray wolves involved in the study, bundles of fibers were found that researchers believe may be the precursors to RAOL and LAOM muscles that most domesticated dog species have. The Siberian Husky was the only breed researchers studied that did not have discernible RAOL and LAOM muscles, likely because it is one of the oldest and most wolf-like species of dog.
Article continues below
Our Featured Programs
See how we’re making a difference for People, Pets, and the Planet and how you can get involved!
These findings, which were published in the Proceedings of the National Academy of Sciences, suggest that the RAOL and LAOM muscles are a direct evolutionary result of domestication by humans to help dogs form more complex facial expressions and communicate better with their two-legged companions. The use of the muscles, it appears, is at least partially voluntary, but humans have positively reinforced the behavior by responding positively to the puppy-dog eye look, and dogs have adapted and evolved over thousands of years of partnership with humans.
“Previous work—and much of it by these same authors—had shown that these muscles were responsible for enhancing positive responses in humans,” says Brian Hare, the director of Duke University’s Canine Cognition Center. “But the current suggests the origin of these facial expressions is after dogs split from wolves.”
Large changes like the addition of muscles rarely happen so quickly as a result of evolution, so researchers believe human attention has been a pretty powerful source acting on canines for thousands of years. It’s also possible that humans unintentionally bred their pets for this preferred trait without even realizing it.
“These muscles evolved during domestication, but almost certainly due to an advantage they gave dogs during interactions with humans that we humans have been all but unaware of,” says Hare.
Angie Johnston, an assistant professor at Boston College who studies canine cognition, says it’s likely that we prefer these more complex facial expressions because they more closely mimic the expressions we might see in human infants, which, of course, we’ve always been infatuated with. Dogs, it seems, are unintentionally (or perhaps intentionally?) usurping this role in many of our lives.
“A big theme that’s come out again and again in canine cognition and looking at the domestication of dogs is that it seems like they really just kind of dove right into our society in the role of being an infant or a small child in a lot of ways,” says Johnston. “They’re co-opting existing systems we have.”
Whoever said a dog is man’s best friend knew what they were talking about; the connection between these two species is profound and long-lasting enough to permanently change the canine generations of the future!
It wouldn’t come as a shock to most of us to learn that dogs are desperate for human attention or that they do their signature puppy-dog eyes to tell you they want attention, but it might surprise a few people to find out that they actually developed special eye muscles to help them get that attention! Share to impress your friends!
Help Rescue Animals
Provide food and vital supplies to shelter pets at The Animal Rescue Site for free! →