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.
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.
Burrows says marathon runners have slow-twitch lower limb muscles, while sprinters have fast-twitch fibers.According to previous Proceedings of the National Academy of Sciences studies, those puppy eyes came from people, not natural selection.
Our initial analysis found the levator anguli oculi medialis muscle in dogs but not wolves. The latest study compares how mimetic muscles contract in dogs and wolves, adds Burrows.