the most valuable advantage man derives from the erect posture is that it exempts the upper limbs from taking any part in the support of the body or in the act of progression ; in other words, it gives him the use of his hands, those "instruments of consummate perfection," as they have well been called, each elaborately framed of twenty-seven bones and numberless fine fibres of muscle and tendon. To the intelli gent use of his hands more than to any other of his faculties man owes the conquests over the forces of nature on which he has reared the fabric of his civilization.
The older anatomists were of the opinion that the four feet of the higher apes were, properly speaking, hands rather than feet, and therefore they included them in a class called the Oztathwmana, or " four-handed " animals. More accurate dissections have shown this view to be erroneous. These members possess certain muscles peculiar to the human foot and not found in the hand, and are therefore feet in the strict sense of the word, and the so-called group of Quadrumana has no existence. Man alone of animals has a hand.
Much of the power of the hand to grasp weapons, tools, and the like comes from the position of the thumb, which is "opposed," as it is called, to the fingers ; that is to say, it can be brought into contact with the tip of any one of them. This is also in a less degree the case with the four feet of the higher apes, but the human thumb is longer and more freely acting, and the palm is wider, thus conferring greater prehensile power on the member (p1. 1, fig. 8, a, c).
Other Anatomical are by no means all the points in which man differs in his anatomy from the highest apes. Thus, in most of his varieties lie has a smooth almost hairless skin, in strong contrast to their hirsute bodies. With few exceptions this is also the most marked in those branches of the human family which are least developed in men tal powers. Most of the apes have a separate bone of the face called the intermaxillary bone, which never appears in the human skeleton. The conformation of the lower jaw is also characteristic. It has been said that man is the only creature which has a chin. It is most distinct in the white race, becomes less marked in the negro, and does not exist in the apes. Although man has the same number of teeth as the higher apes, their development differs in several particulars not necessary to specify here. It is well, however, to correct a prevalent error on this point. The conformation of the human teeth has led many to found arguments that man's diet originally was, and should remain, either veg etable or animal, or of both articles. No conclusion of the kind can be derived from this point of his anatomy. His dentition, indeed, adapts him to eat either animal or vegetable food, and tribes in a state of nature are found living almost exclusively on one or the other ; but the presence of grinding, cutting, and tearing teeth, equally developed, in the jaws of any animal is no proof that it is omnivorous or is confined to a special variety of food. Some monkeys have large canines, yet live on vegeta
bles ; all bats possess well-formed incisors, canines, and molars, yet some are purely fruit-eating, while others live exclusively on animal food.
Brerhz.—Much stress has been laid by some on the shape of the skull in man and the amount and character of the brain-substance which it contains. It is true that in these respects there are obvious differences between him and the animals nearest him in the scale of organic life, hut the precise import of these differences has not been ascertained. Neither in the absolute weight of his brain, nor in its weight in relation to that of his body, does man stand at all at the head of the list of animals. Thus, the weight of a well-developed human brain is about three pounds, which is scarcely or not at all more than in a dolphin of seven or eight feet in length, and is much inferior to that of the elephant and other large animals. Cohsidered in its proportion to the total weight of the body, the brain of man is as r : 37, which is inferior to that of sev eral of the American monkeys, where the proportion is as i : 25, or even less than this.
Writers have therefore sought to discover the signs of the superiority of man in the conformation rather than in the amount of his brain-sub stance. They have said that the mental powers are dependent on the amount of gray matter in the brain. This gray matter is the exterior coating of the brain, and of course the more numerous the folds—or, as they are called, the convolutions—of the brain, the larger area of external surface there will be, and consequently the more gray matter. Hence the complexity of the convolutions of the brain has been asserted by some to stand in direct relation to intellectual power ; and it has been triumph antly pointed out in support of this theory that the brains of the higher apes are much more simple in their convolutions, and therefore have less gray matter, than that of man. This is true, but comparative anatomy has also discovered the opposing fact that the brain of the dog has very much simpler convolutions than that of the sheep, which is notoriously a stupid animal in comparison.
Absence of Tail. —The apparent absence of a tail in man has often been mentioned as one of the obvious distinctions between him and monkeys, but this is a popular error. Anatomically speaking, man has a tail, as any one can see by looking at a human skeleton ; only it is not developed externally, and in this respect he is like several of the higher species of monkeys, which are also usually, though incorrectly, spoken of as tailless.
Besides the above anatomical, there are a number of physiological, differences between man and the apes, especially with reference to the laws of his growth, but they need not occupy us here.