Dogs evolved a special muscle that lets them make puppy dog eyes

Tennease

Legend
Dogs evolved a special muscle that lets them make puppy dog eyes
97

LIFE 17 June 2019

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An explanation for those puppy dog eyes
PavelRodimov/Getty
By Michael Le Page


Human selection has resulted in dogs evolving more expressive faces. They have a facial muscle for making the “puppy dog eyes” that melt many peoples’ hearts that does not exist in wolves – the ancestors of dogs.

This muscle allows dogs to lift up their inner “eyebrow”, which makes their eye look larger. This makes them look more like childlike and also rather sad – the puppy dog eyes look.

It really does make dogs more appealing to us. In 2013, Juliane Kaminski at the University of Portsmouth and colleagues videotaped dogs interacting with strangers at a shelter to see what made them more likely to be adopted.


“The only thing that seemed to have an effect is this eyebrow movement,” she says. Dogs that made this movement more often were adopted sooner.

“It was a surprising result,” says Kaminski, who studies dog-human communication. “That got us really interested.”

Read more: Dogs really can smell your fear, and then they get scared too

In 2017, her team showed that dogs make this movement more often when people are looking at them.

Now Kaminski and some anatomists have dissected 6 dogs and 4 grey wolves to compare their facial muscles (they used existing specimens – no animals were killed for this study).

In dogs, the eyebrow motion is made by a muscle above their eyes, on the inner side nearer the nose, called the levator anguli oculi medialis. Five of the 6 dogs had this muscle. The one exception was a Siberian husky – an ancient breed more closely related to wolves than most dogs.

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Dogs carry a muscle near the eye that wolves lack
Juliane Kaminski

In the wolves – which cannot raise their eyebrows as much – this muscle did not exist. In its place there was a small tendon partially connected to another muscle.
So Kaminski thinks this muscle evolved because people favoured dogs that make this expression.

“It is really different in structure,” she says. “It’s not just something that is used more.”
The movement appears to be under voluntary control, but there’s no evidence that dogs are intentionally using it to manipulate us.

Journal reference: PNAS, DOI: 10.1073/pnas.1820653116
 

hollywood9826

Hall of Fame
Backs up another theory I heard that dogs evolved a "Cuteness" gene that gave them a higher chance of being taken in by a human owner as opposed to being left for dead in the wild.
 

Sentinel

Bionic Poster
Backs up another theory I heard that dogs evolved a "Cuteness" gene that gave them a higher chance of being taken in by a human owner as opposed to being left for dead in the wild.
I read that docile (or friendly) behaviour is what got some close to humans. We selected those that appeared cuters, something like that. Can't recall.
 

Enga

Hall of Fame
I feel like the dog smile is becoming more commonplace as well. Like actual human smiles. Where the lips curl up at the ends. That cant be a natural survival feature. Its probably being encouraged by breeders. I feel like every time I open up YouTube Im gonna see a smiling dog on the recommended videos.
 

hollywood9826

Hall of Fame
I feel like the dog smile is becoming more commonplace as well. Like actual human smiles. Where the lips curl up at the ends. That cant be a natural survival feature. Its probably being encouraged by breeders. I feel like every time I open up YouTube Im gonna see a smiling dog on the recommended videos.

I dont get smiling dog videos. All the videos I get are related to Pro wrestling or Final Fanatsy Brave Exvius.

Maybe I should watch more smiling dog videos :)
 
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