become most strongly
marked by the "anthropoid" apes. These have become accustomed to an
upright gait in their climbing; hence the feet are used for
supporting the body and the hands for grasping. Both thumb and
great toe are opposable; but the foot is a true foot, and the hand a
true hand, in anatomical structure. The face, hands, and feet have
mainly lost the covering of hair. They have no tail, or rather its
rudiments are concealed beneath the skin. These include the gibbon,
the orang, the gorilla, and the chimpanzee.

We can sum up the few attainments of mammals in a line. The lower
forms attained the placental mode of embryonic development; the
higher attained upright gait, hands and feet, and a great increase
of brain. Anatomically considered these were but trifles, but the
addition of these trifles revolutionized life on the globe. The
principal anatomical differences between man and the anthropoid ape
are the following: Man is a strictly erect animal. The foot of the
ape is less fitted for walking on the ground, where he usually "goes
on all fours." The skull is almost balanced on the condyles by which
it articulates with the neck, and has but slight tendency to tip
forward. The facial portion, nose and jaws, is less developed and
retracted beneath the larger cranium or brain-case. This has greatly
changed the appearance of the head. Protruding jaws and chin, even
when combined with large cranium and brain, always give man the
appearance of brutality and low intelligence.

The pelvis is broad and comparatively shallow. The legs, especially
the thighs, are long. The foot is long and strong, and rests its
lower surface, not merely the outer margin as in apes, on the
ground. The elastic arch of the instep must be excepted in the above
description, and adds lightness and swiftness to his otherwise slow
gait. The great toe is short and generally not opposable. The
muscles of the leg are heavy and the knee-joint has a very broad
articulating surface. But the great result of man's erect posture is
that the hand is set free from the work of locomotion, and has
become a delicate tactile and tool-using organ. The importance of
this change we cannot over-estimate. The hand was the servant of the
brain for trying all experiments. Had not our arboreal ancestors
developed the hand for us we could never have invented tools nor
used them if invented. And its reflex influence in developing the
brain has been enormous. The arm