indicate a few of the lines of evidence
which have overcome the last hesitations of scientific men, and closed
the discussion as to the fact.

The very close analogy of structure between man and the ape at once
suggests that they had a common ancestor. There are cases in which two
widely removed animals may develop a similar organ independently, but
there is assuredly no possibility of their being alike in all organs,
unless by common inheritance. Yet the essential identity of structure in
man and the ape is only confirmed by every advance of science, and would
of itself prove the common parentage. Such minor differences as there
are between man and the higher ape--in the development of the cerebrum,
the number of the teeth or ribs, the distribution of the hair, and so
on--are quite explicable when we reflect that the two groups must have
diverged from each other more than a million years ago.

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.