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.
In humans, yawning can start as early as 20 weeks after conception. A yawn is a coordinated movement of the thoracic muscles in the chest, diaphragm, larynx in the throat, and palate in the mouth. By yawning, we help distribute surfactant (wetting agent) to coat the alveoli (tiny air sacs) in the lungs. Generally speaking, we cannot yawn on command.