Do dogs become aggressive when humans smile (revealing our teeths) at them?

Question
Dear Susan,

I am an undergraduate from Singapore. My lecturer mentioned that when humans smile at dogs, dogs are likely to display aggressive behaviour or snarl back. Do dogs become aggressive when humans smile at them, with our teeths revealed?

I have formed a project group of 4 and we are very keen on examining the behaviour of dogs in response to humans smiling. As such, we are keen to test whether this interesting observation is really valid, and present our key findings as part of a graded assignment.

Hope that you can give us some advice =)

Answer
Hello Jasmine, In my years of behavioral work with dogs, I have not found that smiling causes aggression. But you must take into account that they also look at our body posturing, eye contact, feelings (such as nervousness, fear, aggression, anger, calm...), our smell and what they hear. For instance, if we are smiling at them but glaring at them with our eyes, growling at them, backing away from them...their responses will be different. Dogs watch our eyes and body language very much. They have a keen sense about our feelings, especially if we are holding them or have a leash on them. If I am walking my pack and suddenly stop and glare in a particular direction, the dogs will perk up their ears and look in the same direction. Think about this; a stranger comes to your home, they smile at your dog, staring down at them, but back away fearfully. Your dog will act differently if they smile at your dog, make no sound or eye contact and walk past the dog. I believe it is a combination of our actions and responses to dogs which trigger certain behaviors, rather than one particular thing, such as smiling. Keep me posted on your project and let me know about your findings. Regards, Susan