You’re not supposed to let your dog on the sofa. But you can’t resist the look on her face. Turns out there are scientific reasons behind that irresistible facial expression, according to a new study. 

Researcher Anne Burrows and her team found that, over time, dogs developed fast-moving muscles in their faces. In 2019, the team discovered that dogs have also gained the ability to make their eyes look larger—a look better known as puppy-dog eyes. Burrows says the combination helps pups communicate with us.

“Dogs and humans can accurately understand one another’s facial expressions,” she says. “They get us in a way that no other animal does.”