Dogs evolved new eye muscle to communicate with humans

If you sometimes feel as if your dog’s eyes have an almost hypnotic effect, drawing you irresistibly towards the treat jar, you’re not alone. The phrase “puppy dog eyes” perfectly captures how dogs use their eyes to express love and appeal, especially when they want something from us.

We all know how effective a dog’s facial expressions and body language can be in influencing human behaviour. Recent breakthroughs in research reveal the evolutionary science behind this remarkable canine communication. Not only do dogs intentionally give you those wide, adoring puppy dog eyes, but they have evolved a specialised facial muscle that helps them do exactly that.

Understanding puppy dog eyes: More than just a look

Earlier studies showed that dogs alter their facial expressions when communicating with people differently from how they interact with other dogs. They use expressions specifically designed to trigger our nurturing instincts, which often results in extra treats or attention for our canine companions.

Historically, as dogs began their domestic relationship with humans, these expressions helped build bonds and encouraged humans to protect and care for dogs. Evidence suggests this behaviour has been present throughout the history of domesticated dogs, showing a long-standing social adaptation.

Discovery of a new facial muscle aiding communication

Research teams in the UK and USA have identified that dogs evolved specific muscles around their eyes—especially a muscle called the levator anguli oculi medialis (LAOM)—which allows them to raise the inner corners of their eyebrows. This movement makes their eyes appear larger and more infant-like, closely resembling human baby faces, particularly when distressed.

This evolutionary change is absent in wolves, dogs’ closest living relatives, indicating it evolved after dogs diverged from wolves around 33,000 years ago—a rapid transformation in evolutionary terms.

The prominence of this muscle enables dogs to mimic human expressions that trigger caregiving and protective responses in us, thus improving their chances of survival and strengthening their bond with humans.

How to spot this special muscle interaction in your dog

While not obvious in all dogs, especially those with heavy fur around their eyes, this muscle is typically visible in dogs with sparse or differently coloured fur. Try holding treats and watch closely: if your dog raises the inner corner of their eyebrows, creating a 'puppy dog eyes' look, it’s likely this muscle is at work, consciously helping to win your favour.

Why this evolution matters to us and dogs

This adaptation highlights dogs’ unique social flexibility and ability to communicate across species. Leveraging facial expressions that appeal to innate human emotions has helped solidify the relationship between humans and dogs.

This muscular and behavioural trait—known also as Action Unit 101—engages humans on a deep emotional level, possibly exploiting innate neural responses to infantile and sad expressions, which explains why we often can’t resist a dog’s pleading gaze.

Moreover, dogs have shown they can modulate this expression deliberately depending on human attention, demonstrating a cognitive as well as anatomical adaptation that underscores their remarkable social intelligence.

Responsible pet ownership: Appreciating your dog’s communication

Understanding the power behind your dog’s expressive eyes encourages us to be more empathetic and responsible in meeting their needs beyond just treats. Consider this as part of their broader communication toolkit, signalling their emotions and requests.

Remember, ethical breeding and care support dogs in thriving naturally, including nurturing these unique evolutionary traits that deepen the human-animal bond.

For those looking to welcome a dog into their life, it’s essential to seek reputable breeders or consider adopting, ensuring your new companion’s health and behavioural welfare are prioritised.

To know more about finding a puppy or dog, consider checking puppies for sale from reputable breeders and rescues.