Relationship to the Anthropoid Apes
The first question has a predominantly technical interest, and
the authorities are not agreed in replying to it. We saw that, on
the blood-test, man showed a very close relationship to the
anthropoid apes, a less close affinity to the Old World monkeys,
a more remote affinity to the American monkeys, and a very faint
and distant affinity to the femurs. A comparison of their
structures suggests the same conclusion. It is, therefore,
generally believed that the anthropoid apes and man had a common
ancestor in the early Miocene or Oligocene, that this group was
closely related to the ancestral group of the Old World monkeys,
and that all originally sprang from a primitive and generalised
femur-group. In other words, a branch of the earliest femur-like
forms diverges, before the specific femur-characters are fixed,
in the direction of the monkey; in this still vague and
patriarchal group a branch diverges, before the monkey-features
are fixed, in the direction of the anthropoids; and this group in
turn spreads into a number of types, some of which are the
extinct apes of the Miocene, four become the gorilla, chimpanzee,
orang, and gibbon of to-day, and one is the group that will
become man. To put it still more precisely, if we found a whole
series of remains of man's ancestors during the Tertiary, we
should probably class them, broadly, as femur-remains in the
Eocene, monkey-remains in the Oligocene, and ape-remains in the
Miocene. In that sense only man "descends from a monkey."
The far more important question is: How did this one particular
group of anthropoid animals of the Miocene come to surpass all
its cousins, and all the rest of the mammals, in
brain-development? Let us first rid the question of its supposed
elements of mystery and make of it a simple problem. Some imagine
that a sudden and mysterious rise in intelligence lifted the
progenitor of man above its fellows. The facts very quickly
dispel this illusion. We may at least assume that the ancestor of
man was on a level with the anthropoid ape in the Miocene period,
and we know from their skulls that the apes were as advanced then
as they are now. But from the early Miocene to the Pleistocene is
a stretch of about a million years on the very lowest estimate.
In other words, man occupied about a million years in travelling
from the level of the chimpanzee to a level below that of the
crudest savage ever discovered. If we set aside the Java man, as
a possible survivor of an earlier phase, we should still have to
say that, much more than a million years after his departure from
the chimpanzee level, man had merely advanced far enough to chip
stone implements; because we find no other trace whatever of
intelligence than this until near the close of the Palaeolithic
period. If there is any mystery, it is in the slowness of man's
development.
|
