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.
As for the etiology of yawning, for many years it was thought that yawns served to bring in more air because low oxygen levels were sensed in the lungs. We now know, however, that the lungs do not necessarily sense oxygen levels. Moreover, fetuses yawn in utero even though their lungs arenÂ¿t yet ventilated.