Anatomically there are a number of small points which distinguish Man; but they are mainly due to the erect gait. It is sometimes attempted to divide Man as a naked animal. But this is an apparent difference only; the hair is not so much developed upon the body as in the Apes, save in occasional abnormalities, such as the various hairy men and women who can be seen in travelling shows, and to a less extent the Japanese Ainos, but it is present everywhere, as is shown by microscopical investigation of the skin. The skull in Man "is a smooth and imposing, rounded or oval bony case," which contrasts with the smaller and deeply ridged skull of the Anthropoid Apes. The shape of the skull is largely in accord with the large brain. The face does not project so much as in the Anthropoid Apes, though this character must not
be insisted upon too strongly, as in some American Monkeys the face is as little projecting. Still we are now comparing Man with his undoubtedly nearest relatives the Simiidae. In the lower jaw the anterior line at the symphysis is an approximately straight one, that is at right angles to the long axis of the jaw, while Apes have a more retreating chin. The "beautiful sigmoid curve formed by the lumbar and dorsal vertebrae" is more pronounced in Man, but exists not only in the Anthropoids, but in other Apes.[[433]]
Fig. 282.—Foot of Man, Gorilla, and Orang of the same absolute length, to show the difference in proportions. The line a′a′ indicates the boundary between the tarsus and metatarsus; b′b′, that between the latter and the proximal phalanges; and c′c′ bounds the ends of the distal phalanges. as, Astragalus; ca, calcaneum; sc, scaphoid. (After Huxley.)
Fig. 283.—Skeleton of the left pes of a Chimpanzee. (Dorsal aspect.) as, Astragalus; cb, cuboid; cl, calcaneum; ec, ectocuneiform; en, endocuneiform; ms, mesocuneiform; nv, navicular; I-V, digits. (From Wiedersheim's Structure of Man.)
The fore-limbs are relatively short, the extreme length of the arm being such that the outstretched hand does not reach the knee. The thumb is a large and useful digit in Man, much more so than in the Anthropoids. On the other hand the hallux is not opposable. This is, of course, correlated with the upright attitude, as is also the greater relative thickness of that digit, upon which
the greatest stress is laid in walking. As to muscles, the glutaeus maximus is more developed in Man—the Ape which most nearly approaches him being the Gorilla, in which animal the life is less thoroughly arboreal than in some others. The so-called "scansorius" is only present in Man as an occasional occurrence. The rudimentary character of the ear muscles for the movement of the external ear in Man has often been insisted upon, as also their occasional functional activity. But here and elsewhere, so numerous are the abnormalities, that "the gap which usually separates the muscular system of Man from that of the Anthropoids appears to be completely bridged over." These are words of Professor Wiedersheim quoted from Testut, and express a final summary of the matter of muscles in Man and the Apes.
