You’re likely already familiar with puppy dog eyes. You know, the ultimate secret behind that irresistible, heart-melting expression our dogs gift us with every day.
Perhaps, they’re the ultimate reason that makes us hand over our last bite of steak, let our pups sleep on the couch again, and forgive them for shredding our sneakers.
But what exactly are puppy dog eyes, and how did dogs evolve to deploy them so masterfully? Let’s discover more about a dog’s expressive eyes and how they mastered the subtle art of persuasion.
What Are Puppy Dog Eyes?
Puppy dog eyes are ultimately the secret behind your dog’s soulful expression. Dogs are known for having very expressive eyes, but what makes them attractive to us humans? Maybe it’s the fact that they’re capable of moving the muscles of their eyebrows.
This happens courtesy of the dog’s levator anguli oculi medialis (LAOM) muscle. This muscle is responsible for raising the dogs’ inner eyebrow. This muscle has been believed to have evolved as a direct result of domestication.
If we carefully watch our dogs, we will notice how they move their eyebrows in a variety of contexts. We this when they’re shifting their gaze, expressing emotions, and interacting with humans.
Stanley Coren, in the book How To Speak Dog, explains how eyebrow movements can signal emotions such as perplexity and concentration, anger and fear.
What’s interesting is that a groundbreaking study by Juliane Kaminski found that dogs produce more facial expressions when a human is facing them, compared to when a human is turned away.
This tells us that their expressions are socially driven behaviors meant to capture human attention. The most commonly observed (and cherished) movement? The famous inner eyebrow raise, which makes our dog’s eyes ultimately appear larger and more infant-like. This is a trait that us humans find overwhelmingly endearing.
The Evolutionary Advantage of Facial Expressions
Earlier research by Waller et al demonstrated that shelter dogs who frequently raised their inner eyebrows were adopted faster.
This suggests that dogs with expressive faces had a selective advantage in human environments whether through breeding choices or simply by winning the hearts of more potential adopters.
The more often dogs made facial movements that resulted in raising their inner eyebrows, the quicker dogs were rehomed.
This makes one wonder whether dogs have learned to use their facial expressions as a way of getting what they want (human attention) or whether this is just a trait that dogs have been selectively bred for throughout the years.
Did you know? Research by Nagasawa et al revealed that upon noticing the owner’s arrival, dogs moved their left eyebrows for about half a second, suggesting a positive social emotion. They failed to move their eyebrows though in response to attractive toys or when strangers greeted the dog.
This suggests that certain eyebrow movements may be hardwired signals of affection and social bonding, rather than purely strategic manipulations.
Are Dogs Aware of Their “Eye Power?”
At this point, you may be wondering: do dogs consciously use their facial expressions to manipulate humans? Or has this become an automatic behavior due to selective breeding?
While we cannot say for certain, the fact that dogs exhibit these expressions more when humans are watching, seems to strongly suggest that dogs must understand their impact.
However, a new 2024 study from Baylor University seems to suggest that puppy dog eyes aren’t a clever evolutionary trick designed to manipulate humans, as we thought Turns out, coyotes can do it too!
Coyotes: The Unexpected Masters of Puppy Dog Eyes
The study led by Patrick Cunningham examined the levator anguli oculi medialis (LAOM) in coyotes. The findings, published in Royal Society Open Science, reveal that coyotes possess a well-developed LAOM, much like domestic dogs.
This finding now challenges the long-standing belief that s dog’s LAOM muscle evolved purely as a result of domestication. So now what?
Turns out, puppy dog eyes” are unlikely to be the evolutionary ploy meant to melt human hearts. Perhaps what we’re looking at in reality is an ancestral trait shared by multiple species in the Canis genus.
In a nutshell, before dogs ever sat by the fire begging for scraps, their wild relatives were already working the eyebrow game!
Comparing Coyotes, Dogs, and Wolves
To further test this theory, Cunningham’s team compared the facial muscles of coyotes, dogs, and gray wolves.
Interestingly, his research found that while dogs and coyotes shared a well-developed inner eyebrow-raising muscle, gray wolves either lacked the muscle entirely or had a reduced version of it.
If puppy dog eyes were truly an adaptation driven solely by human selection, wolves—who are more closely related to our dogs—would likely have retained it.
So what does this study suggest? Most likely that these canine’s facial expressions must have played a role in facilitating intraspecies communication, hunting coordination, or even social bonding within their social groups.
So rather than having evolved to make dogs look irresistibly cute to us, puppy dog eyes are likely more related to some form of social signaling among wild canids.
References
Patrick Cunningham, Mahita Shankar, Bridgett vonHoldt, Kristin E. Brzeski, Sarah S. Kienle. Coyotes can do ‘puppy dog eyes’ too: comparing interspecific variation in Canis facial expression muscles. Royal Society Open Science, 2024