thousand persons, could beforehand have told anything precise about the
obliquity of the eyebrows with their inner ends puckered, or about the
rectangular furrows on the forehead. So it is with many other
expressions, of which I have had practical experience in the trouble
requisite in instructing others what points to observe. If, then, great
ignorance of details does not prevent our recognizing with certainty
and promptitude various expressions, I do not see how this ignorance
can be advanced as an argument that our knowledge, though vague and
general, is not innate.
I have endeavoured to show in considerable detail that all the chief
expressions exhibited by man are the same throughout the world. This
fact is interesting, as it affords a new argument in favour of the
several races being descended from a single parent-stock, which must
have been almost completely human in structure, and to a large extent
in mind, before the period at which the races diverged from each other.
No doubt similar structures, adapted for the same purpose, have often
been independently acquired through variation and natural selection by
distinct species; but this view will not explain close similarity
between distinct species in a multitude of unimportant details. Now if
we bear in mind the numerous points of structure having no relation to
expression, in which all the races of man closely agree, and then add
to them the numerous points, some of the highest importance and many of
the most trifling value, on which the movements of expression directly
or indirectly depend, it seems to me improbable in the highest degree
that so much similarity, or rather identity of structure, could have
been acquired by independent means. Yet this must have been the case if
the races of man are descended from several aboriginally distinct
species. It is far more probable that the many points of close
similarity in the various races are due to inheritance from a single
parent-form, which had already assumed a human character.
It is a curious, though perhaps an idle speculation, how early in the
long line of our progenitors the various expressive movements, now
exhibited by man, were successively acquired. The following remarks
will at least serve to recall some of the chief points discussed in
this volume. We may confidently believe that laughter, as a sign of
pleasure or enjoyment, was practised by our progenitors long before
they deserved to be called human; for very many kinds of monkeys, when
pleased, utter a reiterated sound, clearly analogous to our laughter,
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