Scientists take a peek behind those sad puppy dog eyes

Clay Curtis
June 18, 2019

A final hypothesis is that exaggerated eyebrow movements expose the white sclera of the dogs' eyes, which humans also have and find appealing in other animals (other primates have darkened sclera to camouflage their gaze).

"Domestic dogs were created by humans, and clearly we selected species that weren't going to bite us or bite our kids", Burrows said. And it's proven to be a remarkable interspecies relationship. "The presence of these anatomical differences between wolves and dogs is a smoking gun for the role of our desire to cooperate and communicate with dogs being a driving force in dog evolution".

Scientists at the University of Portsmouth carried out a study comparing the anatomy and behaviour of dogs and wolves. A muscle that pulls the eyelids toward the ears, which Burrows said happens when dogs are panting and nearly appear to be "smiling", was present in all the dogs dissected except one - the Siberian husky, an ancient breed that is more closely related to wolves.

The researchers conducted their facial anatomy comparison on four wolves and six dogs.

If you've ever fallen for the old "puppy dog eyes" trick, don't feel bad. Ok, not exactly their words.

Such a stark diversion in what in evolutionary terms is a short period of time has led the researchers to believe that humans naturally favour canines able to look at them with big "puppy dog" eyes, giving them a selection advantage. And people may have unwittingly preferred pups that could make that expression.

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The study, published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) journal, found that the inner eyebrow-raising movement makes the dogs' eyes "appear larger, more infant-like and also resembles a movement humans produce when they are sad".

"The findings suggest that expressive eyebrows in dogs may be a result of human unconscious preferences that influenced selection during domestication, "said behavioural psychologist Juliane Kaminski of the University of Portsmouth". Previous research from one of the study authors found that dogs that flashed puppy dog eyes were rehomed more quickly from shelters.

"You don't typically see such muscle differences in species that are that closely related", said report co-author Anne Burrows of Duquesne University in Pittsburgh.

With which co-author Rui Diogo agreed: "I must admit that I was surprised to see the results myself because the gross anatomy of muscles is normally very slow to change in evolution, and this happened very fast indeed, in just some dozens of thousands of years".

Humans tend to pay attention to the upper facial areas of fellow humans during communication, and the dogs could be responding to this dynamic. And can we please have talking dogs someday?

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