Testing yawning hypotheses in wild populations of two strepsirrhine species: Propithecus verreauxi and Lemur catta

Abstract

Yawning, although easily recognized, is difficult to explain. Traditional explanations stressed physiological mechanisms, but more recently, behavioral processes have received increasing attention. This is the first study to test a range of hypotheses on yawning in wild primate populations. We studied two sympatric strepsirrhine species, Lemur catta, and Propithecus verreauxi, of the Ankoba forest (24.99°S, 46.29°E, Berenty reserve) in southern Madagascar. Sexual dimorphism is lacking in both species. However, their differences in ecological and behavioral characteristics facilitate comparative tests of hypotheses on yawning. Our results show that within each species males and females yawned with similar frequencies supporting the Dimorphism Hypothesis, which predicts that low sexual dimorphism leads to little inter-sexual differences in yawning. In support of the State Changing Hypothesis yawning frequencies was linked to the sleep-wake cycle and punctuated transitions from one behavior to another. Accordingly, yawning frequencies were significantly higher in L. catta than in P. verreauxi, because L. catta has a higher basal level of activity and consequently a higher number of behavioral transitions. In agreement with the Anxiety Hypothesis, yawning increased significantly in the 10 min following predatory attacks or aggression. Our findings provide the first empirical evidence of a direct connection between anxiety and yawning in lemurs. Our results show that yawning in these two strepsirrhines occurs in different contexts, but more research will be necessary to determine if yawns are a single, unitary behavior.

An Observational Investigation of Behavioral Contagion in Common Marmosets (Callithrix jacchus): Indications for Contagious Scent-Marking

“…However, the finding that spontaneous yawning is so uncommon among marmosets is noteworthy, because yawning is rather ubiquitous across vertebrates (Craemer, 1924 ; Luttenberger, 1975 ; Baenninger, 1987 ; Gallup et al, 2009 ) and, such low frequency yawning is relatively rare in primates (cf. Palagi et al, 2009 , 2014 ; Zannella et al, 2015 ; the control conditions of Anderson et al, 2004 ; Paukner and Anderson, 2006 ; but see Reddy et al, 2016 ).…”

Auditory Contagious Yawning Is Highest Between Friends and Family Members: Support to the Emotional Bias Hypothesis

“…Yawning can be self-directed and/or displayed to others (Moyaho et al, 2017;Palagi et al, 2019). In human and nonhuman primates, depending on the species, when yawning is shown to others, it can communicate threat (Troisi et al, 1990;Deputte, 1994) and/or physiological and behavioral changes (Provine et al, 1987;Leone et al, 2015;Zannella et al, 2015). In humans, yawning is a socially modulated response because it can be inhibited by actual-and not virtual-social presence and because a yawn can be triggered by someone else's yawn, as a result of a phenomenon known as contagious yawning (Provine, 1989(Provine, , 2005.…”

Physiological outcomes of calming behaviors support the resilience hypothesis in horses

“…Yawning in adult boobies ( Sula granti ) has been explained by the ‘arousal reduction hypothesis’, which claims that this species yawns to down-regulate arousal, after external stressors disrupted its balance 56 . In a similar way, the ‘state changing hypothesis’ predicts that yawning in lemurs ( Lemur catta ) is a potential physiological enhancer associated to the transition from one behavior to another 57 . Both these hypotheses, which explicitly focus on the internal state of the animal, seem to fit with our results on self-directed behaviors in horses.…”