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SEXTON, C.L., R. DIOGO, SUBIAL, F. & BRADLEY, B.J. (2024). Raising an eye at facial muscle morphology in canids. Biology 13:290.

Apr 25, 2024

The evolution of facial muscles in dogs has been linked to human preferential selection of
dogs whose faces appear to communicate information and emotion. Dogs who convey, especially
with their eyes, a sense of perceived helplessness can elicit a caregiving response from humans.
However, the facial muscles used to generate such expressions may not be uniquely present in
all dogs, but rather specifically cultivated among various taxa and individuals. In a preliminary,
qualitative gross anatomical evaluation of 10 canid specimens of various species, we find that the
presence of two facial muscles previously implicated in human-directed canine communication, the
levator anguli occuli medialis (LAOM) and the retractor anguli occuli lateralis (RAOL), was not unique to
domesticated dogs (Canis familiaris). Our results suggest that these aspects of facial musculature do
not necessarily reflect selection via human domestication and breeding. In addition to quantitatively
evaluating more and other members of the Canidae family, future directions should include analyses
of the impact of superficial facial features on canine communication and interspecies communication
between dogs and humans.

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