EVOLUTION OF THE HUMAN SPECIES 163 



appearance of the head is doglike, and the brain-case 

 arches little more than it does in the monkeys, but the 

 face projects forward as a long muzzle, with terminal 

 nostrils close together. In some respects the baboons 

 stand somewhat away from the line leading from the 

 lower to higher anthropoids ; in other characters they 

 approach the latter, for in the teeth especially they are 

 identical with the apes and with the human species. 



The Simiidae, or true apes, possess an overwhelming 

 importance, far beyond that of the baboons and mon- 

 keys. There are only four principal kinds now existing, 

 namely, the gibbon, orang-outang, chimpanzee, and the 

 gorilla, of which the first is much less familiar than the 

 others. The known species of gibbons occur in Indo- 

 China and the Malay Peninsula. The typical animal 

 stands about three feet high; its overarching brain- 

 case, enlarged in conformity with the much greater 

 brain development, has pushed the eyes and face still 

 further around underneath, so that if the animal walks 

 upon all fours the eyes look almost straight into the 

 ground. Therefore it must bend back its head at an 

 extremely uncomfortable angle if it is to remain upon all 

 four feet, but it prefers to raise itself up into the hu- 

 man sitting posture, or, when it walks, it stands erect 

 upon its hind limbs. Hence we who are accustomed 

 to think of ourselves as the only erect animals must 

 revise our opinion, for we find in the gibbon an organism 

 that is nearly, if not quite, as advanced in this respect 

 as we are. One peculiar difference may be pointed out, 

 the walking gibbon stretches out its great long arms 

 to the sides in order to preserve its balance. The 

 animal seems awkward to us, perhaps, but it is possible 



