Dogs with puppy eyes and crinkled brows usually get what they want, whether it's food, a stroll, or attention. And who can resist that look?
But dogs didn't come up with this clever way to manipulate us on their own, or did they just appear cute?
An 18-month study presented at Experimental Biology 2022 found that domesticated dogs have faster facial muscles than their wild predecessor, the wolf.
Instead, dogs have human-like muscles. These traits evolved through domestication.
We think humans selected dogs to have a lot of fast-twitch fibers in their mimetic muscles so they could communicate with us using facial expression,” says Dr. Anne Burrows
the study's senior author and a physical therapy professor at Rangos School of Health Sciences at Duquesne University in Pittsburgh, Pa.
Fast-twitch fibers dominate 70–75% of human mimetic muscles. This study indicated that dogs had more fast-twitch muscle fibers in their mimetic muscles than wolves, says Burrows.
Fast-twitch fibers dominate human mimicry muscles, which control facial expression. This produces readable facial expressions. We also have 25% slow-twitch fibers that can maintain a smile.