servile adjective. âº âeager to âserve and âplease someone âelse in a way that âshows a âlack of ârespect for yourself: As a âwaiter, you âwant to be âpleasant to âpeople without âappearing servile. (Definition of servile from the Cambridge Academic Content Dictionary Â© Cambridge University Press).
That is a good question. In fact, it is not really known why horse yawn. Some suggestions for this behavior are the following: 1  Change of sleeping, napping and waking state. 2  Physical fatigue. 3  Mental stress.  Release of mental or physical stress. Horses will often yawn after a chiropractor session or massage session.
Many animals, including humans, yawn. They do it involuntarily. The signal that initiates a yawn comes from a particular brain region, the PVN (for paraventricular nucleus) of the hypothalamus. It stimulates other brain cells in both the brain stem and the hippocampus to produce the muscle contractions we call a yawn.