Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/122

108 formed largely by the massive jaw-bones, predominates over the brain-case or cranium ; in the man these pro portions are reversed In man the occipital foramen, through which passes the spinal cord, is placed just behind the centre of the base of the skull, which is thus evenly balanced in the erect posture, whereas the gorilla, which goes habitually on all fours, and whose skull is inclined forward, in accordance with this posture has the foramen further back. In man the surface of the skull is com paratively smooth, and the brow-ridges project but little, while in the gorilla these ridges overhang the cavernous orbits like penthouse roofs. The absolute capacity of the cranium of the gorilla is far less than that of man ; the smallest adult human cranium hardly measuring less than 63 cubic inches, while the largest gorilla cranium measured had a content of only 34 i cubic inches. The large pro portional size of the facial bones, and the great projection of the jaws, confer on the gorilla s skull its small facial angle and brutal character, while its teeth differ from man s IQ relative size and number of fangs. Comparing the lengths of the extremities, it is seen that the gorilla s arm is of enormous length, in fact about one-sixth longer than the spine, whereas a man s arm is one-fifth shorter than the spine ; both hand and foot are proportionally much longer in the gorilla than in man ; the leg does not so much differ. The vertebral column of the gorilla differs from that of man in its curvature and other characters, as also does the conformation of its narrow pelvis. The hand of the gorilla corresponds essentially as to bones and muscles with that of man, but is clumsier and heavier ; its thumb is &quot; oppos- able&quot; like a human thumb, that is, it can easily meet with its extremity the extremities of the other fingers, thus possessing a character which does much to make the human hand so admirable an instrument; but the gorilla s thumb is proportionately shorter than man s. The foot of the higher apes, though often spoken of as a hand, is ana tomically not such, but a prehensile foot. It is argued by Professor Owen and others that the position of the great toe converts the foot of the higher apes into a hand, an extremely important distinction from man ; but against this Professor Huxley maintains that it has the characteristic structure of a foot, with a very movable great toe. The external unlikeness of the apes to man depends much on their hairiness, but this and some other characteristics Lave no great zoological value. No doubt the difference between man and the apes depends, of all things, on the relative size and organisation of the brain. While similar as to their general arrangement to the human brain, those of the higher apes, such as the chimpanzee, are much less complex in their convolutions, as well as much less both in absolute and relative weight the weight of a gorilla s brain hardly exceeding 20 ounces, and a man s brain hardly weighing less than 32 ounces, although the gorilla is con siderably the larger animal of the two.

These anatomical distinctions are undoubtedly of great moment, and it is an interesting question whether they suffice to place man in a zoological order by himself. It is plain that some eminent zoologists, regarding man as absolutely differing as to mind and spirit from any other animal, have had their discrimination of mere bodily differences unconsciously sharpened, and have been led to give differences, such as in the brain or even the foot of the apes and man, somewhat more importance than if they Lad merely distinguished two species of apes. Among the present generation of naturalists, however, there is an evident tendency to fall in with the opinion, that the anatomical differences which separate the gorilla or chim panzee from man are in some respects less than those which separate these man-like apes from apes lower in the scale. Yet naturalists agree to class both the higher and lower apes in the same order. This is Professor Huxley s argument, some prominent points of which are the following : As regards the proportion of limbs, the hylobates or gibbon is as much longer in the arms than the gorilla as the gorilla is than the man, while on the other hand, it is as much longer in the legs than the man as the man is than the gorilla. As to the vertebral column and pelvis, the lower apes differ from the gorilla as much as, or more than, it differs from man. As to the capacity of the cranium, men differ from one another so extremely that the largest known human skull holds nearly twice the measure of the smallest, a larger proportion than that ia which man surpasses the gorilla ; while, with proper allow ance for difference of size of the various species, it appears that some of the lower apes fall nearly as much below the higher apes. The projection of the muzzle, which gives the character of brutality to the gorilla as distinguished from the man, is yet further exaggerated in the lemurs, as is also the backward position of the occipital foramen. In. characters of such importance as the structure of the hand and foot, the lower apes diverge extremely from the gorilla ; thus the thumb ceases to be opposable in the American monkeys, and in the marmosets is directed for wards, and armed with a curved claw like the other digits, the great toe in these latter being insignificant in propor tion. The same argument can be extended to other points of anatomical structure, and, what is of more consequence, it appears true of the brain. A series of the apes, arranged from lower to higher orders, shows gradations from a brain little higher than that of a rat, to a brain like a small and imperfect imitation of a man s ; and the greatest structural break in the series lies not between man and the man-like apes, but between the apes and monkeys on one side, and the lemurs on the other. On these grounds Professor Huxley, restoring in principle the Linnean classification, desires to include man in the order of Primates. Thia order he divides into seven families: first, the Anthropini, consisting of man only ; second, the Catarhini, or Old World apes ; third, the Platyrhini, all New World apes, except the marmosets ; fourth, the Arctopithecini, or marmosets ; fifth, the Lemurini, or lemurs ; sixth and seventh, the Cheiromyini and Galeopithecini. It seems likely that, so far as naturalists are disposed to class man with other animals on purely zoological grounds, some such classification as this may, in the present state of compara tive anatomy, be generally adopted.

It is in assigning to man his place in nature on psycho- Psychol logical grounds that the greater difficulty comes into view. ca l clas The same naturalist, whose argument has just been sum- cation * marised against an absolute structural line of demarcation between man and the creatures next in the scale, readily acknowledges an immeasurable and practically infinite divergence, ending in the present enormous gulf between the family of apes and the family of man. To account for this intellectual chasm as possibly due to some minor structural difference, is, however, a view strongly opposed to the prevailing judgment. The opinion is deeply rooted in modern as in ancient thought, that only a distinctively human element of the highest import can account for the severance between man and the highest animal below him. Differences in the mechanical organs, such as the perfection of the human hand as an instrument, or the adaptability of the human voice to the expression of human thought, are indeed of great value. But they have not of themselves such value, that to endow an ape with the hand and vocal organs of a man would be likely to raise it through any large part of the interval that now separates it from humanity. Much more is to be said for the view that man s larger and more highly organised brain accounts for those mental powers in which he so absolutely surpasses the brutes.