THE TONSILLAR EVACUATION HYPOTHESIS OF YAWNING BEHAVIOR

We do not know why we and other animals yawn. Yet because this behavio ur is so commonplace, we are obliged to accept either that yawning has no physiological function or that, because it involves gaping of the mouth, it has some obscure respiratory function. It is suggested that yawning is a powerful reflex to evacuate the palatine tonsillar fossae . As this strong reflex does not have any immediate urgency, it has be come allocated to times of minimal inconvenience. This is reflected in the circadian pattern of yawning in our own species, and explains why we have come to associate yawning with drowsiness and boredom, even t hough this association is not a causal one. If yawning does indeed hav e this function, then by our social sanctions against it we may be sup ressing its effectiveness, leading to endemic tonsillitis in our speci es.