The evolution of dog adorability

Muscle groups in the faces of our dogs differ from those in wolves for one very simple reason...
05 April 2022

Interview with 

Annie Burrows, Duquesne University


Alfie & Peter


Are you one of those people who can’t resist your dog when they cuddle up and look you right in the eye? A new study identifies key anatomical features that may explain what makes those doe-eyed expressions so adorable! Harry Lewis spoke with Annie Burrows, who was in the room with her colleagues Maddy and Jade, at Duquesne University to find out more… 

Harry - To you 3, if you were to look at the face of a dog, what's the cutest part?

Jade - For some reason, I've always liked dog noses. I just think they're so cute and moist, especially like when they're sniffing you.

Maddy - I think the easy answer for me is when they give you the raised eyebrow look. But I also am a sucker for when they give you a big open mouth grin.

Annie - I guess I'm a little bit of an oddball here because I love dog ears. I love when they perk them up and lay them down when they're happy. I just think it's irresistible.

Harry - I'm looking at a picture of Alfie, which is my brother's dog. Alfie's a golden Cockerpoo. He looks a bit like a useless lion. He's got these really exaggerated facial features, particularly his eyebrows; they really make his eyes stand out and my whole family is in agreement that Alfie has the cutest eyes. It's funny because we've spoken to Annie and her research team before about research they did looking at puppy dog eyes. Annie should be kind enough to give us a refresher.

Annie - That research was an extension of some behavioural research that I worked on with a team that's primarily located in the UK. Where they went into various dog shelters in the UK and filmed dogs when people were watching them. What they found was that dogs that made that 'puppy-dog-eye face', were more quickly adopted than dogs who didn't make it. We did some facial dissections to just see what we could find underpinning that movement, and we found that almost all of the domestic dogs that we sampled had the levator muscle that makes that puppy-dog-eye face, whereas none of the wolves had it. It seems that somehow, through dog domestication, people were subconsciously or consciously selecting for that particular facial expression.

Harry - And your work hasn't stopped there. Between the three of you, you found out that these differences in muscle groups are actually represented in the whole face of dogs these days.

Annie - All mammals that we know of have mimetic muscles that are dominated by fast twitch fibres. That's why you get tired holding a smile for your auntie, who is asking you to keep smiling for the photos. That's because our face muscles contract quickly, but they get tired fast. What we found was that both humans and wolves have a large minority of slow twitch fibres in these face muscles. Dogs however, have a very tiny minority of slow twitch muscles. If we think about what do wolves and humans do with their faces that dogs don't, wolves howl. That's their primary mechanism of communication. In order to howl, if you try to make that face yourself, you have to purse your lips and hold that contraction. That requires some slow twitch muscle fibres. Humans use speech and as part of speech, we move our lips in very specific controlled fashions that also require slow twitch muscle fibres. But dogs bark and it doesn't really require much slow twitch movement.

Harry - Annie says, what this is indicative of is that really strong bond that we have with humans' best friend.

Annie - We shouldn't be surprised that we've selected dogs, whether consciously or subconsciously, that do things that we appreciate. Wolves don't bark, but dogs do bark. That's one of the key things that people look for in a dog is protection. But also it points to the huge emphasis that humans dogs place on mutual gaze. This ability to attract one another's attention with facial expression and deepen that bond.


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