THE EVOLUTION OF MAN
We have reserved for a closer inquiry that order of the placental
mammals to which we ourselves belong, and on which zoologists
have bestowed the very proper and distinguishing name of the
Primates. Since the days of Darwin there has been some tendency
to resent the term "lower animals," which man applies to his
poorer relations. But, though there is no such thing as an
absolute standard by which we may judge the "higher" or "lower"
status of animals or plants, the extraordinary power which man
has by his brain development attained over both animate and
inanimate nature fully justifies the phrase. The Primate order
is, therefore, of supreme interest as the family that gave birth
to man, and it is important to discover the agencies which
impelled some primitive member of it to enter upon the path which
led to this summit of organic nature.
The order includes the femurs, a large and primitive family with
ape-like features--the Germans call them "half-apes"--the
monkeys, the man-like apes, and man. This classification
according to structure corresponds with the successive appearance
of the various families in the geological record. The femurs
appear in the Eocene; the monkeys, and afterwards the apes, in
the Miocene, the first semi-human forms in the Pleistocene,
though they must have been developed before this. It is hardly
necessary to say that science does not regard man as a descendant
of the known anthropoid apes, or these as descended from the
monkeys. They are successive types or phases of development,
diverging early from each other. Just as the succeeding
horse-types of the record are not necessarily related to each
other in a direct line, yet illustrate the evolution of a type
which culminates in the horse, so the spreading and branching
members of the Primate group illustrate the evolution of a type
of organism which culminates in man. The particular relationship
of the various families, living and dead, will need careful
study.
That there is a general blood-relationship, and that man is much
more closely related to the anthropoid apes than to any of the
lower Primates, is no longer a matter of controversy. In Rudolph
Virchow there died, a few years ago, the last authoritative man
of science to express any doubt about it. There are, however,
non-scientific writers who, by repeating the ambiguous phrase
that it is "only a theory," convey the impression to inexpert
readers that it is still more or less an open question. We will
therefore 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
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