same fact has been observed in a remarkably savage and isolated tribe,
but chiefly with the women; in another tribe it was observed only on a
single occasion.
Excessive laughter, as before remarked, graduates into moderate
laughter. In this latter case the muscles round the eyes are much less
contracted, and there is little or no frowning. Between a gentle laugh
and a broad smile there is hardly any difference, excepting that in
smiling no reiterated sound is uttered, though a single rather strong
expiration, or slight noise a rudiment of a laugh may often be heard at
the commencement of a smile. On a moderately smiling countenance the
contraction of the upper orbicular muscles can still just be traced by
a slight lowering of the eyebrows. The contraction of the lower
orbicular and palpebral muscles is much plainer, and is shown by the
wrinkling of the lower eyelids and of the skin beneath them, together
with a slight drawing up of the upper lip. From the broadest smile we
pass by the finest steps into the gentlest one. In this latter case the
features are moved in a much less degree, and much more slowly, and the
mouth is kept closed. The curvature of the naso-labial furrow is also
slightly different in the two cases. We thus see that no abrupt line of
demarcation can be drawn between the movement of the features during
the most violent laughter and a very faint smile.[816]
A smile, therefore, may be said to be the first stage in the
development of a laugh. But a different and more probable view may be
suggested; namely, that the habit of uttering load reiterated sounds
from a sense of pleasure, first led to the retraction of the corners of
the mouth and of the upper lip, and to the contraction of the orbicular
muscles; and that now, through association and long-continued habit,
the same muscles are brought into slight play whenever any cause
excites in us a feeling which, if stronger, would have led to laughter;
and the result is a smile.
Whether we look at laughter as the full development of a smile, or, as
is more probable, at a gentle smile as the last trace of a habit,
firmly fixed during many generations, of laughing whenever we are
joyful, we can follow in our infants the gradual passage of the one
into the other. It is well known to those who have the charge of young
infants, that it is difficult to feel sure when certain movements about
their mouths are really expressive; that is, when they really smile.
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