For a very long time, Neapolitan Mastiff breeders in Italy bred their mastiffs to have an imposing presence. In short, they wanted their dogs to scare the bejeebers out of intruders and trespassers. Size, and a mountain of surplus skin folding over itself helped enhance the beastly, if not “otherworldly” visage these guarding dogs presented.  A startled prowler could be forgiven for thinking he had encountered a living, breathing gargoyle.

But there was something else that a generation of breeders endeavored to preserve that worked to amplify the breed’s countenance, and it is so important that it has been written into the breed standard. From the standard: “Expression – Wistful at rest, intimidating when alert. Penetrating stare.”

We remind readers that these words don’t refer to the breed’s overall appearance, but to something very specific: an intense, unwavering, and direct gaze that feels powerful—even unsettling—to the recipient. Indeed, when leveled by a Neapolitan Mastiff, there is little doubt about the dog’s intensity, vigilance, and even challenge toward whoever is being looked at.

You don’t want to be that person.

We got to thinking about the idea of a “penetrating stare.” It goes beyond deep set eyes almost hidden beneath drooping upper lids, and heavy, furrowed brows.

It reveals purpose.

How is it that a dog can produce something that, in a human, is a conscious and intentional choice?

Early breeders knew that the facial structure of their dogs—with deep-set eyes and heavy brows—naturally amplified the intensity of the breed’s gaze. Long before science caught up, these breeders had observed how their dogs’ eyes changed when on heightened alert or confronted with uncertainty, and they selectively bred for this trait. They had no way of knowing about oxytocin or the role of eye contact in canine social communication. Yet, by intuitively selecting for expressive features, those breeders magnified their dogs’ communicative potential—something modern science would later confirm about canine expression.

In 2017, a peer-reviewed research study published in Nature’s Scientific Reports demonstrated that dogs produce more facial expressions—including eyebrow raising and sustained eye contact—when someone is watching them. Someone like, say, a bad guy intent on breaking and entering.

The report by Juliane Kaminski, Jennifer Hynds, Paul Morris and Bridget M. Waller entitled, Human Attention affects Facial Expressions in Domestic Dogs, found that dogs produced significantly more facial movements when a person was looking at them than when the human was turned away. Even the presence of food lacked the same effect. The study f0und what serious dog owners have always known: Expressions are likely communicative and not just involuntary displays of emotion. Neapolitan Mastiff breeders took this further by specializing these cues for a specific function: deterrence. Their selective pressure mimicked natural selection’s role in shaping dog-human communication, but with deliberate intent.

Lest readers shrug their shoulders and wonder why this is noteworthy, we proffer the opinion that this is just shy of astounding. A typical Neapolitan Mastiff breeder in Italy 80 years ago was likely living a rural, working-class lifestyle, often on a farm or estate in southern Italy. They were not dog fanciers as we know it today, but ordinary people—farmers, estate workers, or small landowners—who valued the Mastino for its practical role as a guardian and protector of property, livestock, and family. They were of modest means, and had little to no formal organization to consult.  Their breeding decisions were shaped by practicality — and what worked. And they had figured out what science would prove nearly eight decades later.

That’s impressive.

Image by Okikukai/iStock