Imagine a yawn. You stretch your jaws open in a wide gape, take a deep inward breath, followed by a shorter exhalation, and end by closing your jaws. Ahhh. You have just joined vertebrates everywhere in one of the animal kingdom's most ancient rites. Mammals and most other animals with backbones yawn; fish, turtles, crocodiles and birds do it. People start yawning very early, offering further e...

Fetal neurobehavioral patterns have been considered as indicators of nervous system development. Moreover, the capacity of 4-dimensional sonography to evaluate complex facial expressions allows recognition of common behaviors with which one can appreciate the prenatal functional development of the central nervous system. Using yawning as an example, we review this interpretation on the basis of...

Stretching and yawning (known as pandiculation when they occur together) are under-researched features of behavior. Ethologists agree that almost all vertebrates yawn (Deputte, 1974). Yawning is morphologically similar in reptiles, birds, mammals and fish. These behaviors may be ancestral vestiges maintained throughout evolution with little variation (phylogenetic old origins). Systematic and c...

Yawning is a behavior to which little research has been devoted. However, its purpose has not yet been demonstrated and remains controversial. In this article, we propose a new theory involving the brain network that is functional during the resting state, that is, the default mode network. When this network is active, yawning manifests a process of switching to the attentional system through i...