He raises his left eyebrow when you walk into the room

You’ve probably realized if your dog wags his tail or turns his head when you walk into the room he’s happy to see you. But researchers have discovered another interesting behavior. They recorded dogs’ facial expressions with high-speed cameras and found dogs raise their left eyebrows when they see their owners. The dogs didn’t raise their eyebrows to just any positive stimuli. For instance, they didn’t raise their eyebrows when they saw an attractive toy. So the researchers concluded the eyebrow lift likely reflects “the dog’s attachment to the owner.”