It is one of
those questions that medical experts can’t seem to answer. Why do we yawn, and
furthermore, why is yawning contagious? While there is no concrete answer,
there are theories. Evidence suggests that yawning is a way to communicate changing
environmental or internal body conditions to others. If so, then its contagious
nature is most likely a means of communication within groups of animals. We
don’t need this now because we can talk, but at an earlier evolutionary stage,
it might have been necessary. As for why we yawn in the first place, there is a
theory; it is in response to getting more oxygen, but this has been shot down
by many. We do know that a part of the brain called the periventricular nucleus
is the yawning center of the brain. It contains a number of chemical messengers
that can induce yawns, including dopamine, glycine, oxytocin and ACTH.
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