2024/10/01 by Patrick Cunningham, Mahita Shankar, Bridgett M. vonHoldt +2 · 1 voice · 1 citation
Biochemistry, Genetics and Molecular Biology · Neuroscience · #Animal Vocal Communication and Behavior #Human-Animal Interaction Studies #Olfactory and Sensory Function Studies
paper · pdf · doi:10.1098/rsos.241046
openalex publication_date 2024/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Facial expressions are critical for non-verbal communication. The Canis genus epitomizes the interplay between behaviour and morphology in the evolution of non-verbal communication. Recent work suggests that the levator anguli oculi medialis (LAOM) muscle is unique to dogs ( Canis familiaris ) within the Canis genus and evolved due to domestication. The LAOM raises the inner eyebrows, resulting in the ‘puppy dog eyes’ expression. Here, we test whether the LAOM is a derived trait in dogs by (i) examining the facial expression muscles of a closely related and ancestral wild Canis species, the coyote ( C. latrans ) and (ii) comparing our results with other Canis and canid taxa. We discover that coyotes have a well-developed LAOM like dogs, which differs from the modified/absent LAOM in grey wolves. Our findings challenge the hypothesis that the LAOM developed due to domestication. We suggest that the LAOM is a basal trait that was lost in grey wolves. Additionally, we find inter- and intraspecific variations in the size of the muscles of the outer ear, forehead, lips and rostrum, indicating potential adaptations related to sensory perception, communication and individual-level functional variations within canids. Together, this research expands our knowledge of facial expressions, their evolution and their role in communication.