Different yawns, different functions? Testing social hypotheses on spontaneous yawning in Theropithecus gelada.
Here, we tested hypotheses about the potential functions of yawning based on its intensity and social contexts. Due to their spectrum intensity of yawns (covered teeth/YW1; uncovered teeth/YW2; uncovered gums/YW3), geladas are a good model species for this purpose. We suggest that yawns of different intensity can bear different information according to the performer, the context and the behavioural pattern temporally associated to the yawn event. YW3, mainly performed by high ranking males during periods of high social tension, was frequently associated with an auditory component and often accompanied by scratching (a measure of anxiety). YW1 and YW2, preferentially performed by females, were frequently associated to lip smacking, an affiliative display. In conclusion, even though a clear-cut functional distinction of geladas' yawn intensity is difficult, YW1 and YW2 seem to be more linked to affiliative social interactions; whereas, YW3 seems to be more linked to agonistic and tension situations.
1] Dipartimento di Neuroscienze, Università di Parma, Parma, Italy [2] Centro Ateneo Museo di Storia Naturale, Calci, Università di Pisa, Pisa, Italy.
Alessia
A
Leone
Dipartimento di Neuroscienze, Università di Parma, Parma, Italy.
Pier Francesco
PF
Ferrari
1] Centro Ateneo Museo di Storia Naturale, Calci, Università di Pisa, Pisa, Italy [2] Unità di Primatologia Cognitiva, Istituto di Scienze e Tecnologie della Cognizione, Consiglio Nazionale delle Ricerche, Roma, Italy.
Elisabetta
E
Palagi
D000818:Animals; D001522:Behavior, Animal; D005260:Female; D008297:Male; D012919:Social Behavior; D016671:Theropithecus / Q000502:physiology*; D015000:Yawning / Q000502:physiology*