You know that when you meet a stranger, or even an old friend, and you
greet him, your impulse is to smile as you extend your hand. This is
a smile of recognition, of good-feeling and affection. It has become
instinctive with us, and we do it without ever thinking of its origin
or significance. But there must be some natural reason for this habit.
What is it?
Charles Darwin first pointed out that the muscles used in smiling were
also the muscles used in snarling. You have often seen two dogs, who
are doubtful of each other, approach gradually, pulling back their
lips in a half snarl, as though uncertain of their reception by the
new-comer. It indicated that the dog was ready to fight, if necessary,
and was a sign of warning--to “beware.”
Now, when one smiles, it is probably an evolution of the snarl, which
was originally a sign of defense. We smile on meeting strangers because
our animal ancestors snarled at them--as monkeys do to-day when any
stranger approaches them or attempts to handle them or pick them up.
(This can be observed in the case of any pet monkey.)
However, there is doubtless more to the smile than this. We smile,
it is true, even after we are assured of their friendship, and we
smile when we say “goodby.” We would not naturally snarl under
these circumstances! So the smile is also a physical expression of
happiness--a half-laugh, of gladness, of joy. It is also an expression
of amusement. The smile lifts the muscles of the face, keeping it
young and fresh, and free from wrinkles, and has a beneficial effect
upon it--just as worry and gloom cause the features to droop, and the
corners of the mouth to “sag.” For these reasons, it is safe to say:
“Smile, smile, smile!”