mystery of yawning
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
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mise à jour du
17 mars 2005
Behaviour
1975;53(3-4):268-284
lexique
A comparative study of facial exxpressions of two species of pinnipeds
Edward Miller

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More than a century ago, Darwin (1872) suggested that the "expression of the emotions" of animals could be understood by assuming a causal connection between such expressions and underlying motivational and physiological states. He stressed repeatedly that expressions need have no original or derived signal functions. Intervening research supports many of this basic theses, though we now appreciate that "expression of emotions" through postures, movements and facial appearance often has communicative importance and hence may reflect the operation of natural selection favouring information transfer.
 
Such appears to be true at least for many primate species, though good evidence is sparse for other taxa of mammals. Nevertheless, circumstancial complexitty and permanence of social organisation of a species and the diversity and degree of stereotypy of facial expressions used in social contexts by members of that species.
 
Vibrissae and facial expressions of pacific walruses, Odobenus rosmarus (Linnaeus) and New Zealand fur seals, Artocephalus forsteri (Lesson) and the contexts in which facial expressions occur, are described and compared here. Both species are gregarious, the walrus exceptionnaly so, but their gregariousness reflects adaptation to different ecological problems. That of walruses is probably related largely to the need for energy conservation in the cold enironment they inhabit and probably also mutually beneficial effects of group integrity on locating and maintaining contact with favourable food and ice conditions. Fur seals are gregarious in purposes of breeding and raising the young. Whereas fur seals show few or no anatomical modifications related directly to intraspecific visual signalling, walruses have ther upper canines hypertrophied for that function.
 
Vibrissae [...]
Autogrooming and yawning
 
A. fosteri
During scratching of the facial region and upper throat, A fosteri often slightly erect the vibrissae and close the eyes partially or entirely. Yawning is often terminated with erection of the vibrissae.
 
O Rosmarus
Walruses scratching their forquarters or head may have the eyes partially closed and usually show some degree of erectionof the vibrissae and their movement dorsally, but not dorsomedially.
Walruse sometimes yawn after social encounters in which they showed submissvie behaviour, but most yawning appears simply to be "primed" by preceding submissive behaviour and to have no social function. In yawning, the mystacial pads drawn up dorsally and the mouth is opened widely from the dorsal aspect, yawning imparts a facial expresion similar to, though broader than, a submisive one.