Message #129018

[Bullseye]

It must not be supposed that the divergence of each race from the
other races, and of all from a common stock, can be traced back to any
one pair of progenitors. On the contrary, at every stage in the
process of modification, all the individuals which were in any way
better fitted for their conditions of life, though in different
degrees, would have survived in greater numbers than the less
well-fitted. The process would have been like that followed by man,
when he does not intentionally select particular individuals, but
breeds from all the superior individuals, and neglects the inferior.
He thus slowly but surely modifies his stock, and unconsciously
forms a new strain. So with respect to modifications acquired
independently of selection, and due to variations arising from the
nature of the organism and the action of the surrounding conditions,
or from changed habits of life, no single pair will have been modified
much more than the other pairs inhabiting the same country, for all
will have been continually blended through free intercrossing.
  By considering the embryological structure of man,- the homologies
which he presents with the lower animals,- the rudiments which he
retains,- and the reversions to which he is liable, we can partly
recall in imagination the former condition of our early progenitors;
and can approximately place them in their proper place in the
zoological series. We thus learn that man is descended from a hairy,
tailed quadruped, probably arboreal in its habits, and an inhabitant
of the Old World. This creature, if its whole structure had been
examined by a naturalist, would have been classed amongst the
Quadrumana, as surely as the still more ancient progenitor of the
Old and New World monkeys. The Quadrumana and all the higher mammals
are probably derived from an ancient marsupial animal, and this
through a long series of diversified forms, from some amphibian-like
creature, and this again from some fish-like animal. In the dim
obscurity of the past we can see that the early progenitor of all
the Vertebrata must have been an aquatic animal provided with
branchiae, with the two sexes united in the same individual, and
with the most important organs of the body (such as the brain and
heart) imperfectly or not at all developed. This animal seems to
have been more like the larvae of the existing marine ascidians than
any other known form.

  The high standard of our intellectual powers and moral disposition
is the greatest difficulty which presents itself, after we have been
driven to this conclusion on the origin of man. But every one who
admits the principle of evolution, must see that the mental powers
of the higher animals, which are the same in kind with those of man,
though so different in degree, are capable of advancement. Thus the
interval between the mental powers of one of the higher apes and of
a fish, or between those of an ant and scale-insect, is immense; yet
their development does not offer any special difficulty; for with
our domesticated animals, the mental faculties are certainly variable,
and the variations are inherited. No one doubts that they are of the
utmost importance to animals in a state of nature. Therefore the
conditions are favourable for their development through natural
selection. The same conclusion may be extended to man; the intellect
must have been all-important to him, even at a very remote period,
as enabling him to invent and use language, to make weapons, tools,
traps, &c., whereby with the aid of his social habits, he long ago
became the most dominant of all living creatures.
  A great stride in the development of the intellect will have
followed, as soon as the half-art and half-instinct of language came
into use; for the continued use of language will have reacted on the
brain and produced an inherited effect; and this again will have
reacted on the improvement of language. As Mr. Chauncey Wright* has
well remarked, the largeness of the brain in man relatively to his
body, compared with the lower animals, may be attributed in chief part
to the early use of some simple form of language,- that wonderful
engine which affixes signs to all sorts of objects and qualities,
and excites trains of thought which would never arise from the mere
impression of the senses, or if they did arise could not be followed
out. The higher intellectual powers of man, such as those of
ratiocination, abstraction, self-consciousness, &c., probably follow
from the continued improvement and exercise of the other mental
faculties.