"Perhaps it is useful to
consider one of the strangest displays that can
be seen in many different mammalian species
&endash; "yawning". The purpose of yawning has
been the subject of intense speculation by a
small group of scientists and I receive monthly
e-mail bulletins from a French-based society
dedicated to this subject (www.baillement.com).
This is indeed a curious behavioural display and
is a beautiful example of an involuntary
expression that is pleasurable and that we, as
humans, use voluntarily to deliberately
communicate boredom. It is also highly
infectious with yawning, perhaps even more than
smiling, being likely to induce the same display
in others that see you doing it. Recent brain
imaging studies have even suggested that
observed activation in the temporal lobe during
perception of yawning may actually be directly
triggering "imitation" of this
behaviour."