Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
http://www.baillement.com

mystery of yawning 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mise à jour du
25 avril 2016
Anim Sci J.
2016;88(1):195-200
Presence of contagious yawning in sheep
Yonezawa T, Sato K, Uchida M, Matsuki N, Yamazaki A

Chat-logomini

 Tous les articles sur la contagion du bâillement
All articles about contagious yawning 

Abstract

Contagious yawning is triggered by others yawning, and it has previously been reported in humans, primates and several experimental and companion mammals. Whereas it might be a response to an innate releasing mechanism, contagious yawning is also considered to involve emotional contagion. Here, we demonstrate that sheep, the animal model of livestock animals, also experience contagious yawning. Twelve adult castrated Corriedale sheep were used in this study. Pairs of sheep were adjacently restrained with or without a wooden divider panel to shield them from viewing the other. Their behaviors were video-recorded for 3_days in each condition. Sheep yawned 2.0_±_1.1 and 1.2_±_1.1 times/day/head in the unshielded and shielded conditions, respectively. Unshielded restrained sheep yawned within 1_min after the other one 11.1% of the time, while shielded pairs did not exhibit contagious yawning. Rumination was also highly synchronized under the unshielded condition. These data reveal that contagious yawning and behavioral synchronicity occur in ruminants like sheep, making them a suitable animal model to investigate contagious yawning and the underlying mechanism.


Contagious yawning is a well-known phenomenon where yawning is triggered by another individual yawning. It has been described in many mammalian species such as humans (Provin 1986; Senju et al. 2007; Norscia & Palagi 2011), chimpanzees (Anderson et al. 2004; Campbell & de Waal 2011), gelada baboons (Palagi et al. 2009), bonobos (Demuru & Palagi 2012) macaque monkeys (Paukner & Anderson 2006), wolves (Romero et al. 2014), domestic dogs (Joly-Mascheroni et al. 2008; Romero et al. 2013), rats (Moyaho et al. 2014) and budgerigars (Miller et al. 2012).
 
While spontaneous yawning is common among vertebrate species (Baenninger 1987; Heusner 1946), it is unknown whether more species could yawn contagiously or not. Contagious yawning is reported to be a response to an innate releasing mechanism (Provine 1986; Bartholomew & Cirulli 2014), and it is considered to be based on the organism's capacity for empathy or emotional contagion (Amici et al. 2014; Madsen et al. 2013).
 
Emotional contagion is the perception of expressive behaviour to transfer emotional states from one individual to another (Blakemore & Decety 2001). Indeed, contagious yawning is not observed in young children (Anderson & Meno 2003; Millen & Anderson 2011) or patients with autism spectrum disorders (Senju et al. 2007) although spontaneous yawning is observed even in foetuses (Sherer et al. 1991). Thus, contagious yawning could be a good tool to assess the levels of emotional contagion.
 
The empathetic behaviours appear to emerge developmentally and phylogenetically (Gallup 1998; Provinelli et al. 1994; Premack & Woodruff 1978). Since there is convincing evidence for self-other recognition and empathy in primates (Gallup 1970; Bard et al. 2006), these behaviours are mainly investigated using humans and primates. Although some researchers recently reported emotional contagion, particularly related to contagious yawning in other species such as domestic dogs (Joly-Mascheroni et al. 2008; Romero et al. 2013), rats (Moyaho et al. 2014) and budgerigars (Miller et al. 2012), there is still no report in ungulate species to our knowledge.
 
Among those species, sheep are good experimental animals because they have stable genetic background and they are easily supplied, and it is known to have social facilitation and concurrent behaviours (Rook & Penning 1991; Michelena et al. 2006; Gautrais et al. 2007; Clayton 1978). It is reported that ruminating, resting, grazing, and walking are synchronised within its familiar herds of sheep (Rook & Penning 1991; Michelena et al. 2006; Gautrais et al. 2007). Sheep are also reported to have developed social recognition skills using visual facial cues (Kendrick 2004; Broad et al. 2000; Peirce & Kendrick 2002). These reports lead us to the hypothesis that sheep also experience contagious yawning.
 
This study examined whether contagious yawning occurs in sheep. In the experiments, a pair of sheep was video recorded while they were adjacently restrained with or without a wooden divider panel that shielded them from their stall mate's behaviour. Ruminating, resting, and barking behaviours were also observed. To clarify whether yawning contagion could be derived from visual stimuli, their behaviours were also observed while they were restrained next to a television monitor showing a video clip of a sheep that was yawning or ruminating.
 
DISCUSSION
 
Our findings revealed that contagious yawning occurs even in quadrupedal animals such as sheep. In this study, unshielded restrained sheep yawned within 1 minute after the other one 11.1% of the time, while shielded pairs never exhibited contagious yawning. Moreover, the number of contagious yawns in the unshielded condition was significantly higher than that of the randomised data, while there was no significance in the shielded condition. These data reveal that contagious yawning occurs in ruminants like sheep, also indicating that sheep is one of suitable animal models to investigate contagious yawning and the underlying mechanism. Since primates and dogs are not so suitable as experimental animas because of animal facility limitations and ethical problems, sheep could be a useful model for basic research into contagious yawning.
 
Stress is reported to change animal behaviours in the most situations. Generally, rumination are mostly observed when the animals are relaxed (Provine 1986; Bartholomew & Cirulli 2014; Gautrais 2007). Restraint is well-known as one of stressors and reported to induce the plasma cortisol level in sheep (Matthews & Parrott 1991). Therefore, the restraint stress might not have some effects on all the results. On the other hand, sheep are also prone to isolation stress (da Costa et al. 2004). In this study, the total numbers of rumination and yawning were significantly larger under the unshielded condition in comparison with the shielded condition. Since sheep were only isolated under the shielded condition, their behaviours would be affected by unignorable isolation stress. However, the relationship between stress and yawning is still under controversy. While yawning occurs frequently when the human are under stress or tired (Thompson 2011), the stress-induced yawn is not so reproduced in dogs (Silva et al. 2013). In this study, the total number of yawning was larger under the unshielded condition. It is implied that yawning occurs infrequently under the isolation stress in sheep, which could be opposite from other species. In any case, our data could suggest that contagious yawning occurs in sheep because the accuracy of contagious yawning was higher than the randomized data only under the unshielded condition.
 
The yawn contagion prevalence was 11.1% in this study. In the previous report, the rates are 45-55% in humans (Provin 1986; Senju et al. 2007; Norscia & Palagi 2011), and 33% in chimpanzees chimpanzees (Anderson et al. 2004; 1 Campbell & de Waal 2011). Since these results are derived from different conditions and statistical tests, they cannot be compared directly. Nevertheless, it is likely that the ratio of contagious yawning in sheep is lower than others. At least several reasons are considered as follows.
 
Sheep could not yawn during rumination. When the yawns that occurred during the other's ruminating were excluded, 30.8% of yawns were synchronised (8/26 yawns), which is subtle nearer to other data.
 
They were examined under the restraint stress. Although dogs did not change contagious yawning frequency under the stress in the previous report (Silva et al. 2013), the different type of stress or species might have some effect of stress on contagious yawning occurrence.
 
Sheep brain might have more primitive or simple yawning contagion mechanism than primates. Further research is needed which reason is more affirmative.
 
Previous report about social dynamics indicates that activity synchronicity is considered to be necessary for social cohesion in gregarious species (Clayton 1978). It has been reported that ruminating, resting, grazing, and walking are synchronised in sheep herds (Rook & Penning 1991; Michelena et al. 2006; Gautrais et al. 2007). Indeed, it was observed that the other behaviours than yawning such as ruminating were also synchronised in this study. The relationship of mechanism between social dynamics and contagious yawning remains unknown.
 
As there are many reports about social dynamics in sheep, further study in sheep can reveal difference or commonality of them. The present results do not clarify which factor(s) triggered contagious yawning. It could be induced by viewing others' yawns (Provine 1986; Senju et al. 2007) and/or hearing yawning sounds (Arnott et al. 2009). Even video images or computer animations of yawning induce contagious yawning in human and primates (Senju et al. 2007; Paukner & Anderson 2006; Campbell et al. 2009). The wooden board placed between the partnered sheep in this study visually shielded the neighbour's behaviour and partially blocked aural information. To clarify the effect of visual stimuli on contagious yawning, the sheep were shown a muted video clip of another sheep yawning or ruminating as a control. Unfortunately, there were no significant differences between video contents. Although sheep are reported to have social recognition skills involving the use of visual cues from others' faces (Kendrick 2004; Broad et al. 2000; Peirce & Kendrick 2002), no relevant studies have employed a video-based approach. It is suggested that sheep could not just recognise a face in the video clips under our experiment condition or visual effects are not sufficient to induce contagious yawning in sheep. Further studies are needed to clarify the mechanism of contagious yawning.
 
In conclusion, our findings suggest that contagious yawning occurs in sheep. Therefore, sheep could be a good animal model to investigate contagious yawning and collect important information for animal welfare and livestock management.