Evolution of facial muscle anatomy in dogs. Juliane Kaminski, Bridget M. Waller, Rui Diogo, Adam Hartstone-Rose, Anne M. Burrows. Proceedings of the National Academy of Sciences Jul 2019, 116 (29) 14677-14681; DOI: 10.1073/pnas.1820653116
Since the beginning of canine domestication roughly 15,000 years ago, each dog breed has been genetically designed through selective breeding to be adorable in their own unique way. Take for instance the bulldog with its squat body and droopy jowls. Picture the golden retriever with its lean build and long beautiful locks. And who could forget the chihuahua with its bulgy eyes and rat-like little body- so ugly it’s cute!
Cuteness is actively bred into dogs; however, a recent study conducted at the University of Portsmouth suggests humans might have inadvertently bred the ultimate weapon of cuteness into man’s best friend. That’s right, today we are breaking down the evolution of puppy dog eyes.
Puppy Dog Eye Procedure
Turns out all pups possess a special genetic feature that make them even more irresistible: a muscle known as the levator anguli oculi medialis, or LAOM. With this knowledge, a team of scientists led by Juliane Kaminski of the University of Portsmouth sought to discover how it became part of a pup’s genetic makeup.
Kaminski and her colleagues analyzed the facial anatomy of various dog breeds and wolves by dissecting cadavers provided by taxidermists, museums, and wildlife organizations. (No animals were harmed for testing). As the researchers expected, all the domesticated dog breeds possessed LAOM. The wolf specimens lacked LAOM; however, they possessed a few weak muscle fibers where LAOM rests in their domesticated counterparts.
The team also conducted research on living dogs and wolves. One at a time, a dog or wolf was observed by a researcher for a two-minute period. During observations researchers recorded the frequency and intensity of eyebrow movement. The researchers found both dogs and wolves displayed some eyebrow movement; however, only dogs could achieve high intensity eyebrow arching.
Brows on Fleek
In recent years, thick manicured eyebrows have dominated the beauty scene. In the 90s, eyebrows plucked razor-thin were all the rage. Around 2,500 BC Egyptian men and women filled in their brows with black makeup to offset their heavily lined eyes. Roughly 130,000 years ago our Neanderthal brethren rocked unkempt eyebrows on their pronounced brow ridges.
No matter when or how they were styled, eyebrows have always played a crucial role in nonverbal communication between humans. Kaminski’s study proves that eyebrow movement is an effective form of nonverbal communication between species that might have inadvertently given dogs of the past a leg up in selective breeding.
How Does LAOM Work?
LAOM is small but strong collection of muscle fibers that allow dogs to intensely raise their inner eyebrow. This movement mimics the expression humans make when they are sad or worried.
Try it out for yourself. Go to a mirror. Think sad thoughts and frown. If you notice that the inner corner of your eyebrows arch upwards, then good news: you are either a human or a dog. Congrats!
Kaminski and colleagues believe a dog’s ability to mimic human facial expressions may trigger a nurturing response in their caretaker, thus giving the pooch an evolutionary advantage in selective breeding. The study proves humans actively or inadvertently favored dogs with the ability to enlarge their eyes giving them a baby-like appearance, forever changing the facial anatomy of domesticated canines.