Dogs have developed muscles which allow their eyes to "appear larger, more infant-like and also resembles a movement humans produce when they are sad".

By Ian Horswill

Posted on June 19, 2019

“Don’t look at me like that,” millions of us have told our pets as they stare longingly at us on our way out the door.

Dogs, more than any domesticated animal, are desperate for human eye contact. When raised around people, they begin fighting for our attention from as young as four weeks old. It’s hard for most people to resist those puppy-dog eyes.

Researchers at University of Portsmouth’s Dog Cognition Centre have found that dogs have evolved muscles around their eyes, which allow them to make expressions which prompts a “nurturing response”.

Previous studies have shown how such canine expressions can appeal to humans, but this research, published in the Proceedings of the National Academy of Sciences, shows there has been an anatomical change around dogs’ eyes to make it possible, BBC News reported.

This evolution in dogs’ eyes has created what the researchers call “expressive eyebrows” and to “create the illusion of human-like communication”.

“When dogs make the movement, it seems to elicit a strong desire in humans to look after them,” says the study’s co-author Dr Juliane Kaminski.

Study co-author Juliane Kaminski from University of Portsmouth.

The movement of the muscle allows dogs’ eyes to “appear larger, more infant-like and also resembles a movement humans produce when they are sad”.

Kaminski said that humans would have an “unconscious preference” to protect and breed from dogs with such an appealing trait, giving them an evolutionary advantage and reinforcing this change in subsequent generations.

In 2017, Kaminski found that dogs moved their eyebrows more often while a human paid attention to them, and less often when they were ignored or given food (which, sorry to say, is a more exciting stimulus for them than human love).

That suggested the movement is to some degree voluntary. On our side of these longing glances, research has also shown that when dogs work these muscles, humans respond more positively. And both man and mutt benefit from a jolt of oxytocin when locked in on each other.

This isn’t simply a fortuitous love story, in which the eyes of two species just so happen to meet across a crowded planet. Like all the best partnerships, this one is more likely the result of years of evolution and growth. If dogs developed their skill for eyebrow manipulation because of their connection to humans, one way to tell would be to look for the same capacity in wolves.

Dogs eyes

Dogs split off from grey wolves 33,000 years ago and those eyebrow-raising muscles appear to be an addition to dogs’ anatomy. In the four grey wolves the researchers looked at, neither muscle was present. (They did find bundles of fibres that could be the precursors to the two muscles).

In five of the six breeds of dog the researchers looked at, both muscles were fully formed and strong; in the Siberian husky, the wolflike, oldest breed of the group, the researchers were unable to locate one of the muscles.