206.), and in the barbarous races of mankind, to imitate whatever they
hear deserves notice, as bearing on the subject of imitation. Since
monkeys certainly understand much that is said to them by man, and when
wild, utter signal-cries of danger to their fellows (57. See clear
evidence on this head in the two works so often quoted, by Brehm and
Rengger.); and since fowls give distinct warnings for danger on the
ground, or in the sky from hawks (both, as well as a third cry,
intelligible to dogs) (58. Houzeau gives a very curious account of his
observations on this subject in his Facultes Mentales des Animaux,
tom. ii. p. 348.), may not some unusually wise ape-like animal have
imitated the growl of a beast of prey, and thus told his fellow-monkeys
the nature of the expected danger? This would have been a first step in
the formation of a language.
As the voice was used more and more, the vocal organs would have been
strengthened and perfected through the principle of the inherited
effects of use; and this would have reacted on the power of speech. But
the relation between the continued use of language and the development
of the brain, has no doubt been far more important. The mental powers
in some early progenitor of man must have been more highly developed
than in any existing ape, before even the most imperfect form of speech
could have come into use; but we may confidently believe that the
continued use and advancement of this power would have reacted on the
mind itself, by enabling and encouraging it to carry on long trains of
thought. A complex train of thought can no more be carried on without
the aid of words, whether spoken or silent, than a long calculation
without the use of figures or algebra. It appears, also, that even an
ordinary train of thought almost requires, or is greatly facilitated by
some form of language, for the dumb, deaf, and blind girl, Laura
Bridgman, was observed to use her fingers whilst dreaming. (59. See
remarks on this head by Dr. Maudsley, The Physiology and Pathology of
Mind, 2nd ed., 1868, p. 199.) Nevertheless, a long succession of vivid
and connected ideas may pass through the mind without the aid of any
form of language, as we may infer from the movements of dogs during
their dreams. We have, also, seen that animals are able to reason to a
certain extent, manifestly without the aid of language. The intimate
connection between the brain, as it is now developed in us, and the
faculty of speech, is well shewn by those curious cases of
brain-disease in which speech is specially affected, as when the power
to remember substantives is lost, whilst other words can be correctly
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