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How dog facial expressions evolved to connect with people

January 05, 2023

Many dog owners swear their pets smile when they’re happy. But are dogs really using their faces to express emotion? Or is it just wishful thinking from us humans? It turns out, dogs actually do have facial expressions and research suggests the reason has to do with domestication and their relationships with humans. Let’s go behind the smile to unpack the science of how dog facial expressions evolved to connect with people.

Why do dogs make facial expressions?

Perhaps the best-known dog facial expression is “puppy dog eyes”, that longing look dogs use to beg or show affection. Scientists believe they can trace the roots of that expression back to the earliest interactions between dogs and humans.

In a study published in the journal, Proceedings of the National Academy of Sciences (PNAS), researchers say the process of “domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans.” How did it do that, exactly?

The researchers pointed to a particular muscle, the levator anguli oculi medialis, that is responsible for raising the inner eyebrow. This muscle is uniformly present in dogs, but it is not in all wolves. Furthermore, behavioral studies found that “dogs produce the eyebrow movement significantly more often and with higher intensity than wolves do, with highest-intensity movements produced exclusively by dogs.” They say this movement “resembles an expression that humans produce when sad, so its production in dogs may trigger a nurturing response in humans.” In other words, the researchers suggest “that dogs with expressive eyebrows had a selection advantage and that ‘puppy dog eyes’ are the result of selection based on humans’ preferences.”

So, it turns out dogs may very well use their facial expressions to their advantage — whether to increase their chances of survival or just to get another treat.

Do dog facial expressions mean anything?

“Puppy dog eyes” may be one thing, but what about all the other emotions dogs seem to convey with their facial expressions? Many dog owners say they can tell when their pet is happy, sad or confused just from their face alone. But is there anything to that?

Experts widely agree that dogs do show emotions via their facial expressions. But they stress that facial expressions are just part of a dog’s body language and should be interpreted in the right context. For example, a dog might smile when happy, and a wagging tail and relaxed body posture can confirm the animal is feeling good. But a dog might also “smile” when they are feeling frightened or aggressive. Here, flat ears, growing, whimpering or other signs of tension can reveal what the smile really means.

Scientists say dog facial expressions are more often used to communicate with humans, rather than simply express emotions. One study found that “canine facial expressions are influenced by the presence of humans and their level of attention. These findings suggest a communicative function, rather than emotional, that can serve as a nonverbal language to express aversive responses such as pain.”

Research has also shown that dogs are incredibly skilled in reading human communicative cues, and that eye contact between dogs and humans is crucial for guiding dog−human social interaction. So, dog facial expressions can do more than just convey emotion, they can be a true form of communication and connection between dogs and humans.

How to keep your dog happy and smiling

Every dog lover wants to see their furry friends happy and smiling as much as possible. One way to bring out the happy is to give your dog the nutritious and great-tasting treats they love. Consider using NutriSource’s SuperStar Soft & Chewy Training Treats to strengthen the bond between you and your dog and you’ll both be smiling in no time.

Shop local and buy NutriSource products from one of the independently owned and operated pet suppliers in your community.