In the following pictures, the dog seems to be smiling to the camera. People staring at these picture also tend to feel comfortable and relaxed, presumably because they think it's very happy playing with the swing.

However, my question is, is the dog really happy, or we are just (incorrectly) interpreting the dog's facial expression according to our experience used to read humans' facial expression?

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    $\begingroup$ Not a scientific article but a pretty good answer: smbc-comics.com/?id=3172 $\endgroup$
    – Ashafix
    Jul 19 '16 at 18:28
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    $\begingroup$ I have no reference, so this is not an answer, but when I was a veterinary student I was told that the dog smile as illustrated above is seen only in dogs, and is only used to humans. It is apparently true that dogs can discriminate smiling humans from a blank face, so the leap is not completely ridiculous. $\endgroup$
    – iayork
    Aug 18 '16 at 17:30

I would say no, facial expressions in humans do not generally relate to facial expressions in other animals. Even though there are some cases (as described in the comments an previous answers) that refer to domesticated animals, I do not know of any convincing evidence that the facial expressions of humans are faithfully interpreted, or even mimicked, by other animals - at least outside the group of great apes. Further, the cases arguing that (domesticated) animals can do it are often anecdotal (I am not saying wrong!). Taking an evolutionary perspective, I would not even expect it to be happening (or rather by very close relatives only, i.e. other great apes) because facial expressions as behavioural signals are part of communication and therefore often rather species-specific.

But not only that ... there is emerging evidence that facial expressions are not even interpreted uniformly in all human populations: in this article by Crivelli et al. (2016) in Front. Psychol. the authors argue to include anthropological data to cognitive studies. According to their findings, not including a human evolutionary perspective might result in strong biases. They strengthen their point by giving an example of differential interpretation of facial expressions in a Melanesian society which is described in more biological terms in PNAS [Crivelli et al. (2016)]. What they found is that adolescents of this society interpret a facial expression (gasping face) that in other societies conveys fear as a threatening and angry expression.

Generalising this means that if there is divergence in signaling by facial expressions even among human populations, I would consider it unlikely that there is a general homologous system of facial expressions among mammals. There might, however, be a trend in domesticated animals to understand human expressions and adapt behaviour according to them. It still is an extraordinary claim to infer from this that they can actually mimic these expressions, and I have not yet seen convincing evidence for that.


Our cousins in the primate world share the same base facial expressions as we do, happy, sad, disgust, etc; it would make sense that other mammals are capable of facially displaying emotional registers.

However, canines can't pass the mirror test for self awareness, but chimps can. However however, it is known that dogs' oxytocin level rises when they stare into our eyes (similar for female human into her baby's eyes). Thus, if the dog is experiencing elevated feel good neurotransmitters, then a smiling face would appear to make sense.

The question is, have you seen dogs smiling in abused situations?

My other thought on this is that the smile could just be a pavlovian manifestation: you become happy shen the dog smiles, so the dog smiles more--the dog has an association of you being happy to something good happening to it, so it wants to make you happy more.

Sorry I don't have a definite answer for you, but afaik the neuroscience / psychology of dogs keeps expanding in complexity, so I would say that yes, the dog is happy.

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    $\begingroup$ Beautifully written answer. Please do add some links and/or sources to back up what you wrote. $\endgroup$
    – L.B.
    Jun 19 '16 at 16:45
  • $\begingroup$ This post requires references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted. Please see this meta discussion for more. $\endgroup$
    – MattDMo
    Jun 20 '16 at 1:21
  • $\begingroup$ Thanks for the kind words :) most of my post came from stuff I remembered from my psychology classes at university. I would have to hunt down my old textbooks, but to anyone interested you can pick up an introductory / survey psych textbook for a penny on Amazon; check out the chapters on neurotransmitters and emotion. The dog and primate example are pretty common. I'll have to keep in mind to get sources prior before answering further. It was kind of a spur of the moment thing ^-^ glad that it was intriguing to you! $\endgroup$
    – Fluidity
    Jul 15 '16 at 10:52

Get to know dogs' facial expressions and you will find that there are comparable facial expressions of a canine with that of humans.


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