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Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
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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

mystery of yawning 














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2 novembre 2015
A Metaphor:
religious beliefs exist because yawning is contagious
Olivier Walusinski
European Neurology. 2015;74(5-6):322


Disinhibition of anti-cultural behavior: A means of adaptation in early hominids? Kozintsev A, Butovskaya M  
God is the only being who, to reign, does not need to exist. Charles Baudelaire, Fusée. 1867.
Can a physiological behavior explain a cultural phenomenon? Here we suggest that the neuropsychological mechanisms underlying contagious yawning elucidate, at least in part, the cognitive processes involved in religious beliefs.
About yawning
Yawning is a stereotyped behavior, observed in cold-blooded and warm-blooded vertebrates, from reptiles with rudimentary "archaic" brains to human primates, in water, air, and land environments. Yawning appears to be an ancestral vestige maintained throughout evolution with little variation, bearing witness to its early phylogenetic origins. Three different types of yawning can be distinguished. "Universal yawning", which is seen in all vertebrates, is associated with daytime circadian rhythms, i.e. sleep / arousal and hunger / satiety. "Emotional yawning", which is only seen in mammals, has a calming effect after stress. Ethologists call this type of behavior a displacement activity. Finally, "contagious yawning", which is observed only in great apes, in humans, in dogs under certain conditions and perhaps in social parrots (budgerigar) and rats, is the ability to respond to yawning in others [1,2].
Many emotional responses (laughing, crying) and many behaviors (vomiting, scratching and hysterical behaviors such as the dancing manias in medieval Europe) are considered contagious but do not display the automation and constancy of contagious yawning. It is nevertheless possible that they share common neurobiological mechanisms, all necessary for social life. Religious practices entail emotional packages and comprise postural mimicry and synchrony, which appear to be the support mechanisms for membership in a social group. What are the neurobiological substrates required for these practices? Are they also involved in contagious yawning?
Neurobiological mechanisms underlying contagious yawning
Experimental research indicates that contagious yawning relies on the capacity known as mental state attribution on one hand, and the capacity to build knowledge of mental states in oneself, on the other. These two conditions involve a "theory of mind" (TOM) [3]. This ability to infer mental states and emotions in others represents an evolved psychological capacity most highly developed in humans and, up to a point, in non-human primates. In addition, humans can also empathize with others, that is, share their feelings and emotions in the absence of any direct emotional stimulation to themselves. Innate emotional and motivational processes are found to exert unconscious and automatic influences on social judgments and behavior. Facial expressions are the efferent part of a biologically anchored system of basic affects; they are also part of a preprogrammed or prewired form of communicative competence. This system enables the receiver to unconsciously, automatically imitate the sender's bodily state and facial expression [4]. Contagious yawning, the onset of a yawn triggered by seeing, hearing, reading, or thinking about another person yawning, occurs as a consequence of the ability to infer or empathize with what others want, know, or intend to do, requiring the neurological substrate responsible for self-awareness and empathic modeling, by which a corresponding response is produced in oneself. Self-awareness, recognizing that I have a mental state (I believe x to be true) equates to first-order intentionality. Ascribing mental states to others (I believe that you believe x to be true) is a form of second-order intentionality. This is the common level of analysis noted above. Yet intentionality can continue to still deeper levels, as in third-order intentionality (I believe that you believe that I believe x to be true) and fourth-order intentionality (I believe that you believe that I believe that you believe x to be true). While chimpanzees "only just aspire" to second-order intentionality, humans engage in deeper and deeper levels of mind, not essential for yawning's contagiousness [5]. Functional imaging suggests that activation of the underlying network integrating these processes is also responsible for decoding cognitive empathy. As a neocortical activity (inferior-frontal cortex, superior temporal sulcus, ventral premotor cortex, right parietal cortex, posterior cingulate, anterior insula, and amygdala), contagious yawning is a sign of involuntary empathy. Thus, we see that, through evolution, a behavior can be recycled for different purposes according to the increasing complexity of the central nervous system, correlated with the richness of social interactions [6].
One of the most basic and powerful activities of the brain involves the ability to quickly detect other agents in the environment. Agents are not to be confused with objects, and the capacity to quickly and accurately distinguish between objects and agents in the environment is clearly crucial to survival. The mental mechanism responsible for recognizing agents is called the Agency Detection Device (ADD). In addition to instantaneously identifying the people and creatures that cross our paths, we are also prone to make up agents based on minimal input from any of our senses. ADD's effectiveness and speed are due to the application of ready inferences and expectations about what agents are like. A complete picture of the nature and significance of agents is the result of ADD working together with TOM. As ADD examines the objects we encounter, those displaying characteristics of agents activate TOM, which in turn initiates a rich array of inferences. ADD and TOM function rapidly, effortlessly, automatically, and mostly non-consciously, competing to trigger contagious yawning. Thus, the human brain is endowed with an array of tools for organizing and interpreting the world [7,8].
Brief review of the neuropsychology of religious beliefs
The religious meaning of yawning, although interesting, is not within our scope here. Rather, our focus is on how the human species, so enamored with its own logical and critical facilities, has been able to hold strong religious beliefs. The overwhelming majority of believers today are the cultural descendants of a small group of prosocial religions that emerged and spread worldwide. These religions elicit deep devotion and extravagant rituals, often directed at Big Gods - powerful, morally concerned deities who are believed to monitor human behavior. These gods are believed to deliver rewards and punishments according to how well people meet the particular, often local, behavioral standards, including engaging in costly actions that benefit others. Partly out of fear of supernatural punishment, people will comply with norms that they believe to be monitored by agents. Religious concepts activate various functionally distinct mental systems, present also in non-religious contexts, and "tweak" the usual inferences of these systems. Religion is not an evolutionary adaptation per se, but a recurring cultural by-product of the complex evolutionary landscape that sets the cognitive, emotional and material conditions for ordinary human interactions, recruiting the brain's capacity for metarepresentation, which is the forming of representations of representations. Core religious beliefs minimally violate ordinary notions about how the world is, with all of its inescapable problems, thus enabling people to imagine minimally impossible supernatural worlds that solve existential problems, including death and deception [9,10].
Gods and supernatural beings, the concepts around which religion form, are represented and processed by the human mind as social agents, as members of the human social network, because the kinds of beings that gods are said to be, are only intelligible in relation to the natural ontological category of "person". Neuroimaging studies find that thinking about or praying to God activates brain networks known to be implicated in mentalizing. Mentalizing is associated with a tendency to personify God, and the same mentalizing biases that are typically found when reasoning about other peoples' minds are also found when inferences are made about God's mind. This effect of cognitive constraint dramatically shapes the way people intuitively think about gods. Supernatural beings not only feature many of the ordinary properties of person-like agents but, important to the present context, are also naturally represented as agents with whom we can interact [11,12].
Cognitive biases make humans receptive to religious ideas, but do not themselves generate them. This means that an explanation for the universality of religion has to be found elsewhere. We possess a suite of sophisticated cognitive adaptations for social life, which make accessible certain concepts that are associated with religion, but they require further cultural support. Transcultural neuroimaging studies have demonstrated that one's cultural background can influence the neural activity that underlies both high- and low-level cognitive functions [13,14].
Yawning and religious beliefs: the intriguing crossroads between neuropsychology and neurotheology
We process God concepts using the suite of mental mechanisms involved in social intelligence. Through the activity of ADD and TOM, we automatically evaluate the import, intentions, and utility of all intentional agents, and especially other humans. The fact that God beliefs engage this automatic, low-level cognitive support is one key to explain why gods are humanlike. In this way, religious beliefs activate the same neural and cognitive systems that guide social interaction with other humans. Gods are seen by some as plausibly real because thoughts about them activate TOM systems, ADD, contagion-avoidance and social exchange. As stated above, ADD and TOM systems are the underlying neural mechanisms that the brain relies on to trigger contagious yawning. Because God concepts capitalize on these and other powerful cognitive systems in the human mind, they have proven extremely resilient.
Without the contagiousness of yawning, the belief in God would be impossible.
We are not claiming the discovery of a "God-spot" in the brain, as Vilayanur S. Ramachandran famously did in 1998, after examining patients with temporal epilepsy who reported profound religious feelings during and after seizures [15]. Our syllogism is admittedly simple and lacking in scientific evidence, but our hope is that it will stimulate further scientific studies on yawning, a poor relative of the more visible research areas.
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