Sure, it may seem as if your dog is just giving you a cute and dopey look, but a new study suggests much more is going on. Your cute and dopey dog is skillfully arching its levator anguli oculi medialis muscle—a muscle that seems to have evolved for precisely this reason—to execute what scientists have dubbed the "AU101: inner eyebrow raise." In other words, he's giving you puppy dog eyes to get what he wants, explains the New York Times. The upshot of the study in the Proceedings of the National Academy of Sciences is that dogs evolved to manipulate humans to increase their odds of survival, and they did so by developing the aforementioned muscle to better move their eyebrows.
"When dogs make the movement, it seems to elicit a strong desire in humans to look after them," says the study out of the UK's University of Portsmouth, per the BBC. The key discovery came from a comparison of wolves, which do not have the LAOM muscle. Dogs split off from wolves about 33,000 years ago, notes the Atlantic, meaning they developed the new facial muscle in a "remarkably short" amount of time. And it stuck: Dogs able to move their eyebrows would be more likely to be nurtured by humans, which would give them "a selection advantage over others and reinforce the 'puppy dog eyes' trait for future generations," says researcher Juliane Kaminsky, per a news release. (Read more dogs stories.)