least.

As a rule, the flat sole of the foot is set on the ground, with the toes
extended, as in man, but the toes are sometimes doubled under in
walking. The orang rarely touches the ground with the sole or the closed
toes, but walks on the outer edge of the foot, the feet being bent
inward as if clasping the rounded sides of a bough. The other species
have a tendency in the same direction, the legs being bowed and the
gait rolling. In using the hands in walking, the closed knuckles are
usually placed on the ground, though occasionally the open palm is
employed. The whole movement of these animals is strikingly awkward, and
goes to indicate that there can be no satisfactory compromise between
life in the tree and on the ground.

The significant fact in these attempts to walk is that none of the
anthropoid apes show any inclination to revert to the quadruped habit.
Their attitude is in all cases an approach toward the erect one, which
posture is attained by the gibbon. The arms are used not as walking but
as swinging organs. Evidently their mode of life in the trees has
overcome all tendency toward the quadruped motion in these apes and
developed a tendency toward the biped. But none of them have gained the
muscular development of the leg known as the calf, nor an adjustment of
the joints to the erect attitude, since none but the gibbon walks erect,
and it does so only at occasional intervals.

The conclusion to be derived from all this is that the man-ape was in
its early days much more truly a biped than are any of the species
named. Like them, it had no tendency to revert to the quadruped habit.
The shortness of its arms was unsuited to this, while rendering it
impossible for the animal to progress in the semi-erect, swinging
fashion of the other anthropoid apes. As a result of its bodily
formation, it may have begun to walk erect at a very remote date, with
a consequent straightening of the joints and muscular development of the
legs. When this condition was fully attained, it was practically a man
in physical conformation, though mentally still an ape, and with a long
development of the brain to pass through before it could reach the human
level of mind.

The far-reaching conclusions here reached are all based on one important
fact, the shortness of man's arms as compared with the disproportionate
length of arm in the anthropoid apes. This, for the reasons given,
rendered the adaptation of the man-ape to life i