Dogs, more so than almost any other domesticated species, are desperate for human eye contact. When raised around people, they begin fighting for our attention when they’re as young as four weeks old. It’s hard for most people to resist a petulant flash of puppy-dog eyes—and according to a new study, that pull on the heartstrings might be exactly why dogs can give us those looks at all.
A paper published today in the Proceedings of the National Academy of Sciences found that dogs’ faces are structured for complex expression in a way that wolves’ aren’t, thanks to a special pair of muscles framing their eyes. These muscles are responsible for that “adopt me” look that dogs can pull by raising their inner eyebrows. It’s the first biological evidence scientists have found that domesticated dogs might have evolved a specialized ability used expressly to communicate better with humans.
For the study, a team at the University of Portsmouth’s Dog Cognition Centre looked at two muscles that work together to widen and open a dog’s eyes, causing them to appear bigger, droopier, and objectively cuter. The retractor anguli oculi lateralis muscle and the levator anguli oculi medialis muscle (mercifully known as RAOL and LAOM) form two short, straight lines, which connect the ring of muscle around a dog’s eye to either end of the brow above.
These researchers have long been interested in the ways dogs make eye contact with humans and, in particular, how they move their eyebrows. In 2017, Juliane Kaminski, the lead author of the new paper, found that dogs moved their eyebrows more often while a human paid attention to them, and less often when they were ignored or given food (which, sorry to say, is a more exciting stimulus for them than human love). That suggested the movement is to some degree voluntary. On our side of these longing glances, research has also shown that when dogs work these muscles, humans respond more positively. And both man and mutt benefit from a jolt of oxytocin when locked in on each other.
