Alice Galotti, Giulia Fausti, Grazia Casetta, Andrea Paolo Nolfo, Veronica Maglieri, Elisabetta Palagi
In the last decade, increasing attention has been devoted to exploring some aspects of yawning in non-human animals. With their chin red mark, bony paranasal swellings, male large brains and long canines, drills (Mandrillus leucophaeus) offer a robust model for testing hypotheses on the phenomenon. We identified two yawn variants (covered, YCT and uncovered teeth, YUCT ) which differ in terms of recruitment of muscular action units (AUs). We tested the effects of several variables (sex, dominance rank, context) on the duration of the yawn and the probability of YCT or YUCT occurrence...
April 22, 2024: Primates; Journal of Primatology