The limbs of the orang are less elongated and less extremely specialized for arboreal life than those of the gibbon but more so than those of the chimpanzee and the gorilla. The skull is rounded and of great vertical height, with broad, bony ridges above the orbits and a great median crest on top of the skull in old males. The lower jaw of the orang is stout and deep, and, although used as a fighting weapon, the canine tusks are much less prominent than in either the gibbon, chimpanzee, or gorilla. Of all anthropoids this jaw most nearly resembles that of the Piltdown man.

Fig. 19. The Chimpanzee. This figure shows certain facial characteristics which are preserved in the Neanderthal race of men. Note also the shortening of the thumb and the enlargement of the big toe. Photograph from the New York Zoological Park.

In the chimpanzee we observe the very prominent bony ridges above the eyes, like those in the Trinil and Neanderthal races of men. The prognathous or protruding tooth rows and receding chin suggest those in the Heidelberg, Piltdown, and Neanderthal races. When the chimpanzee is walking (Fig. 18) the arms reach down below the level of the knees, whereas in the higher races of man they reach only half-way down the thighs. Thus, the fore limb, although much shorter than that of the gibbon, is relatively longer than that of any human race, recent or ancient. We observe also in the walking chimpanzee (Fig. 18) that the upper part of the leg, the thigh-bone, or femur, is relatively long, while the lower part, the shin-bone, or tibia, is relatively short. Indeed, both in the arm and in the leg the upper bones are relatively long and the lower bones are relatively short. These proportions, which are inheritances of arboreal life, are in very marked contrast to those observed in the arms and legs of the Neanderthal race of men, in which the limbs are of the terrestrial or walking type.

ANCESTRAL TREE OF THE ANTHROPOID APES AND OF MAN

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From the unknown and ancestral stock of the anthropoid apes and man the GIBBON was the first to branch off in Oligocene times; the ORANG then branched off in a widely different direction. The stem of the CHIMPANZEE and of the GORILLA branched off at a more recent date and is more nearly allied to that of man. Five early human races have been found in Europe in Glacial or Pleistocene times, but no traces of other primates except the macaques, which are related to the lower division of the baboons, have been found in Europe in Pleistocene times. Modified after Gregory. (For latest discovery see Appendix, Note VII.)