书城教材教辅科学读本(英文原版)(第5册)
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第3章 Man and Brute(2)

"Of all the countless creatures that now throng the busy scene of life, or that successively have faded from existence, not one has been permitted to inquire from whom or whence it received its being. Man alone has been taught to recognize his Maker"s hand, which formed all living things, each in its separate sphere, and still upholds and guides the wondrous system He Himself created."So then it is man"s intellectual power which raises him to this lofty height, utterly unapproachable by the rest ofGod"s creatures. In man the brain-case is developed; in the lower animals, on the contrary, the development is in the direction of the face,and not of the skull. The face is always disproportionately large as compared with the skull.

That this is no mere chance accident may be readily seen by comparing the heads of a man, a gorilla, and ahorse. If a tape were passed round a person"s head, so as to cross the eyebrows and both ears, and the two ends were then tied at the nape of the neck, it would show roughly the proportion between skull and face, and give some idea of the enormous brain capacity in man.

Turn from this to examine the heads of any of the lower animals, and the contrast is at once sharp and striking. Even in the great apes, and they make the nearest approach to man, it is the head, quite as much as the hand, that stamps them as a distinct creation.

Let us try to find the reason for this special development. The face is designed mainly as a lodgment for the sense organs of sight, smell, and taste. These sense organs mean to the brute creation the main part of their existence. The keenness of sight, smell, and also of hearing is as necessary to the hunted as to the hunting animal-in the one case togive the signal of danger, in the other to guide the hungryprowler to its prey. What then is more natural than that these sense organs and of course their bony lodgments should be developed at the expense of the rest of the head? Length of face, for instance, means a corresponding development of the nasal cavities, with greatly increased capacity for the spread of the nerves of smell. In every animal that depends upon its sense of smell either for its safety or its food, we find an elongated face.

Then next as regards the mouth. Feeding being the chief business of these creatures" lives, it is quite naturalto look for a special development of the organ of taste to guide them in the choice of their food, and of the jaws and teeth to masticate it.

Moreover, with many of them, the mouth, jaws, and teeth are not merely feeding organs, but weapons of attack and defense. In either case the animal depends upon them for its very existence. The brain, such as it is, has no other duty than to act as overseer to these special organs; here we have in a nutshell the reason why there is special development of the face at the expense of the skull or brain-case.

Just one other thought, and that was the only reasonfor mentioning the condyles at the base of the skull. Man walks erect. He is the only one of God"s creatures to whom this attitude is natural. Is this an accident? Let us see. The head rocks to and fro on these condyles, which fit into corresponding hollows in the top of the Atlas vertebra. In no other animal do we find these condyles placed so far for ward as in man. If we examine the various types of animals from man downwards, we find the condyles nearer and nearer to the back of the skull. The consequence is that the weight of the head does not rest directly on the spine, as it does in man, but upon the muscles and ligaments which bind the two together.