Obviously most animals recognise tone of voice - they know if you're calling them a good dog or a bad dog etc, but do animals, especially domestic ones recognise smiling? Just by smiling or frowning at an animal, without saying anything, would it recognise it? Thanks.
A pet that knows you will eventually learn your expressions and anticipate your mood, however the concept of smiling and frowning does not exist. In nature cues are taken from eyes and teeth. If you smile at a strange dog and your teeth are showing it may well take it as a sign of aggression, the same goes for prolonged eye contact.
I agree with jenky. My animals all seem to respond to my mood...picking up on with I am smiling at them etc...I can get away with giving my dog a staring cross look & she knows as I am the leader of our family 'pack' that she must back off at that point...but I'd never risk doing that to a dog I don't know.
Similarly when I smile at her she wags her tail, but she tells really bad jokes....
I have a completely deaf mastiff. She watches my expression constantly and knows if she is in trouble. Mr apricot tended not to smile much and she was constantly anxious around him. When he began to smile at her she relaxed. Just need to get him to smile at me now!