Structure of Man
Examining the structure of man more closely, we find this strong
suggestion of relationship greatly confirmed. It is now well
known that the human body contains a number of vestigial
"organs"--organs of no actual use, and only intelligible as
vestiges of organs that were once useful. Whatever view we take
of the origin of man, each organ in his frame must have a
meaning; and, as these organs are vestigial and useless even in
the lowest tribes of men, who represent primitive man, they must
be vestiges of organs that were of use in a remote pre-human
ancestor. The one fact that the ape has the same vestigial organs
as man would, on a scientific standard of evidence, prove the
common descent of the two. But these interesting organs
themselves point back far earlier than a mixed ape-human ancestor
in many cases.
The shell of cartilage which covers the entrance to the ear--the
gristly appendage which is popularly called the ear--is one of
the clearest and most easily recognised of these organs. The
"ear" of a horse or a cat is an upright mobile shell for catching
the waves of sound. The human ear has the appearance of being the
shrunken relic of such an organ, and, when we remove the skin,
and find seven generally useless muscles attached to it,
obviously intended to pull the shell in all directions (as in the
horse), there can be no doubt that the external ear is a
discarded organ, a useless legacy from an earlier ancestor. In
cases where it has been cut off it was found that the sense of
hearing was scarcely, if at all, affected. Now we know that it is
similarly useless in all tribes of men, and must therefore come
from a pre-human ancestor. It is also vestigial in the higher
apes, and it is only when we descend to the lower monkeys and
femurs that we see it approaching its primitive useful form. One
may almost say that it is a reminiscence of the far-off period
when, probably in the early Tertiary, the ancestors of the
Primates took to the trees. The animals living on the plain
needed acute senses to detect the approach of their prey or their
enemies; the tree-dweller found less demand on his sense of
hearing, the "speaking-trumpet" was discarded, and the
development of the internal ear proceeded on the higher line of
the perception of musical sounds.
We might take a very large number of parts of the actual human
body, and discover that they are similar historical or
archaeological monuments surviving in a modern system, but we
have space only for a few of the more conspicuous.
The hair on the body is a vestigial organ, of actual use to no
race of men, an evident relic of the thick warm coat of an
earlier ancestor. It in turn recalls the dwellers in the primeval
forest. In most cases--not all, because the wearing of clothes
for ages has modified this feature--it will be found that the
hairs on the arm tend upward from the wrist to the elbow, and
downward from the shoulder to the elbow. This very peculiar
feature becomes intelligible when we find that some of the apes
also have it, and that it has a certain use in their case. They
put their hands over their heads as they sit in the trees during
ram, and in that position the sloping hair acts somewhat like the
thatched roof of a cottage.
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