s of their highest representatives, the
anthropoid or manlike apes, have been found in Miocene rocks. The fact
that these large apes are now few in number of species, is no proof that
many forms of them may not have formerly existed, and among these we may
class the ancestor of man.

V

THE FREEDOM OF THE ARMS

Man's ancestor is by no means the only form of ape that has made the
earth's surface its place of residence. The baboon is one example of a
number of forms that dwell habitually upon the ground, though they have
not lost their agility in climbing. But these species have returned to
the quadruped habit, to which the equal length of their limbs adapts
them. All the anthropoid apes dwell to some extent upon the ground, but
these can neither be called quadrupeds nor bipeds, their usual mode of
progression being an awkward compromise between the two. The same may be
said of one of the lemurs, the propithecus, the only member of its tribe
that attempts to move in the erect attitude. It does not walk, however,
but progresses by a series of jumps, its arms being held erect, as if
for balancing.

Of the apes, though many can stand upright, the gibbon is the only one
that attempts to walk in this position. This is a true walk, though not
a very graceful one. The animal maintains a fairly upright posture, but
walks with a waddling motion, its body rocking from side to side. Its
soles are placed flat on the ground, with the great toes spread
outward. Its arms either hang loosely by its side, are crossed over its
head, or are held aloft, swaying like balancing poles and ready to seize
any overhead support. Its walk is quickly changed to a different motion
if any occasion for haste arises. At once its long arms are dropped to
the ground, the knuckles closed, and it progresses by a swinging or
leaping motion, the body remaining nearly erect, but being swung between
the arms.

None of the other anthropoid apes ever walk erect, though they assume at
times the upright posture. But though they use all their limbs as
walking organs, they show no tendency to revert to the habit of the
quadrupeds. Their motion is like that of the gibbon when in haste, a
series of jumps or swings between the supporting arms. The shortness of
their arms, however, prevents them from standing erect, like the gibbon,
in doing this; and they bend forward to a degree depending on the length
of their arms, the chimpanzee the most, the orang the