Yawning?

Since antiquity yawning has attracted a moderate interest among philosophers, psychologists, physiologists, as well as educators, moralists and physicians. Organisms from birds to men and from the womb to the deathbed were found to be displaying it. While sometimes satisfying to the producer, its display is offensive to the lay observer. Hippocrates had it on his lists of useful 'natures.' Aristotle dropped a few words on the matter. Boerhaave elevated its function to the intellect of animals. Haller has commented on its relation to the acoustic system, blood-flow, and baby sleep. Darwin mentioned it in connection with emotional behavior. Some modern authors praised its beneficial effects on respiration and smell. In the 1960s, Ashley Montagu tried to correct the contemporary failure to explain the behavior by the fact of raised CO2 and arterial compression. It also interested some neurologists, especially in its association with the encephalitis lethargica in the 1920s, with 'spasmodic yawning,' with epilepsy, not to speak of hysteria. As to boredom or its stimulus, a 40-page dissertation survives from the court of Frederick the Great of the 18th century condemning idleness, a subject that also inspired Blaise Pascal and William James. But in the Hindu world, public yawning was a religious offense.