Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Most mammalian species produce facial expressions.
Historically, animal facial expressions have been considered inflexible and involuntary displays of emotional states rather than active attempts to communicate with others. We presented dogs with an experimental situation in which a human demonstrator was either attending to them or turned away, and varied whether she presented food or not.
Dogs produced significantly more facial movements when the human was attentive than when she was not. The facial architecture underlying such facial expressions is highly conserved among mammals 1 , suggesting that human facial expression is based on evolutionarily ancient systems. Therefore, it would seem reasonable to debate the extent to which such facial expressions are underpinned by sophisticated cognitive processes.
Historically, animal facial expressions including human, to an extent have been considered inflexible and involuntary displays e. There is some evidence that non-human primate facial expressions can be mediated by the presence of an audience, suggesting that the sender has some understanding of whether the expressions can be seen by others 4 , 5 , 6 , 7 , 8. Waller et al. Similarly, Scheider et al. To date there is no systematic experimental evidence, however, that facial expressions in species other than primates, are produced with similar sensitivity to the attention of the audience.
Domestic dogs are a potentially interesting model for this kind of research as they have a unique history. Dogs follow communicative gestures more once the humans eyes are visible and the gesture is clearly directed at them Dogs also follow the gaze of a human to a target only if eye contact had been established prior to the gaze shift The more often dogs produced a specific facial movement, Action Unit which raises the inner eyebrow the quicker they were re-homed Raising the inner eyebrow changes the visual appearance of the eyes and makes them look bigger, a key feature of paedomorphism juvenile features present in the adult.
