42 HUMAN PHYSIOLOGY. 



an obvious effort. The arm of the higher apes has as wide a range of motion 

 as that of Man, so far as' its articulation is concerned; but it is only when the 

 animal is in the erect attitude, that the limb can have free play. Thus the 

 structure of the whole frame must be conformable to that of the hand, in the 

 way that we find it to be in Man, in order that this organ may be advantage- 

 ously applied to the purposes which it is adapted to perform. But it cannot be 

 said with truth (as some have maintained) that Man owes his superiority to his 

 hand alone ; for without the mind by which it is directed, and the senses by 

 which its operations are guided, it would be a comparatively valueless instru- 

 ment. Man's elevated position is due to the superiority of his mind and of its 

 material instruments conjointly; for if destitute of either, the human race must 

 be speedily extinguished altogether, or reduced to a very subordinate grade of 

 existence. 



2. The next series of characters to be considered, are those by which Man is 

 adapted to the erect attitude. On examining his cranium, we remark that the 

 occipital condyles are so placed, that a perpendicular dropped from the centre 

 of gravity of the head would nearly fall between them, so as to be within the 

 base on which it rests upon the spinal column. The foramen magnum is not 

 placed in the centre of the base of the skull, but just behind it; so that the 

 greater specific gravity of the posterior part of the head, which is entirely filled 

 with solid matter, is compensated by the greater length of the anterior part, 

 which contains many cavities. There is, indeed, a little over-compensation, 

 which gives a slight preponderance to the front of the head, so that it drops 

 forwards and downwards, when all the muscles are relaxed ; but the muscles 

 which are attached to the back of the head are far larger and more numerous 

 than those in front of the condyles, so that they are evidently intended to 

 counteract this disposition ; and we find, accordingly, that we can keep up the 

 head for the whole day, with so slight and involuntary an effort, that no fatigue 

 is produced by it. Moreover, the plane of the foramen magnum, and the sur- 

 faces of the condyles, have a nearly horizontal direction when the head is up- 

 right; and thus the weight of the skull is laid vertically upon the top of the 

 vertebral column. If these arrangements be compared with those which pre- 

 vail in other Mammalia, it will be found that the foramen and condyles are 

 placed in the latter much nearer the back of the head, and that their plane is 

 more oblique. Thus, whilst the foramen magnum is situated, in Man, just 

 behind the centre of the base of the skull, it is found, in the Chimpanzee and 

 Orang Outan, to occupy the middle of the posterior third (Fig. 1); and, as we 

 descend through the scale of Mammalia, we observe that it gradually approaches 

 the back of the skull, and at last comes nearly into the line of its longest dia- 

 meter, as we see in the Horse. Again, in all Mammalia except Man, the plane 

 of the condyles is oblique, so that, even if the head were equally balanced upon 

 them, the force of gravity would tend to carry it forwards and downwards : in 

 Man, the angle which they make with the horizon is very small; in the Orang 

 Outan, it is as much as 37; and in the Horse, their plane is vertical, making 

 the angle 90. If, therefore, the natural posture of Man were horizontal, the 

 plane of his condyles would be brought, like that of the Horse, into the verti- 

 cal position ; and the head, instead of being nearly balanced on the summit of 

 the vertebral column, would hang at the end of the neck, so that its whole 

 weight would have to be supported by some external and constantly-acting 

 power. But for this, there is neither in the skeleton, the ligamentous appara- 

 tus, nor the muscular system of Man, any adequate provision; so that in any 

 other than the vertical position, his head, which is relatively heavier than that 

 of most Mammalia, would be supported with more difficulty and effort than it 

 is in any other animal. 



3. The position of the face immediately beneath the brain, so that its front 



