Behaviour 2019
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Impacts of Communication via Facial Expression on Variation in Muscles around the Eye in Domesticated Canids
Courtney L. Sexton. The George Washington University, Washington, DC, United States

Humans and canids share a history unique among examples of interspecies coevolution across the Animal kingdom. While domesticates of the Mammalian order share many behavioral and physical traits, the dog (C. familiaris) is perhaps the only other animal with which modern humans have communicated regularly for at least the past 20,000 years. We can trace changes in facial muscle morphology among primates, and especially the striking differentiation of human facial muscles (Diogo 2018), which aided an increasing demand for visual communication of emotions. Kaminski, et al. (2017) demonstrate that the quantity and variety of facial expressions produced by domestic dogs increased in response to attentive humans. Burrows et al. (2017) investigate whether or not the production of these expressions in dogs is linked to changes in facial musculature over time, as determined by comparison of facial muscles between wolves and dogs. Further examination of the presence and robusticity of the levator anguli occuli medialis and the retractor anguli occuli lateralis across the canid family reveal possible trends toward a shift in facial muscle morphology concurrent with canid domestication.