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.
There are a number of theories that attempt to explain why animals and people yawn. It is likely that there are a number of triggers for the behavior. However, there are comparatively few theories that attempt to explain the primary evolutionary reason for the yawn.nother hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite, and other phenomena. These chemicals include serotonin, dopamine, glutamic acid, and nitric oxide.