I40 EVOLUTION OF THE EARTH 



and hence more active, swinging from tree to tree by the hand 

 with great agility. They rest in the sitting posture, sometime 

 stand or walk, but run on all fours. Jaws and teeth are thei 

 chief defense. 



The gorilla (Fi^. 28) is by far the most formidable of al 

 the great apes, for its huge size and strength and its unparal 

 leled ferocity make it a veritable terror. An authentic re 

 corded size makes the gorilla five feet one and one-half inche 

 tall and 418 pounds in weight. Its lower limbs, whil 

 enormously powerful, are disproportionately short. If th 

 limbs bore a human proportion to the torso, the creature 

 would stand at least seven feet in height, with a weight o 

 half a thousand pounds I The huge size of this ape has force* 

 it to become partially terrestrial, but instead of becomin; 

 more man-like as an adaptation to ground-living, it has take; 

 a yet more brutal aspect, more like a bear than a human being 



All of these apes, the orang, chimpanzee, and gorilla, ar 

 degenerating from the higher condition of their commo: 

 ancestor with mankind, the chimpanzee least, the gorilla mos 

 of all. The gibbons (Fig. 29), however, of which there ar 

 several species, while the most remote from mankind in actua 

 relationship, have probably retained in greater degree tha 

 any others the habits and development of the anthropoid sten 

 form. They are wonderful acrobats, their relatively small siz 

 and immensely long and powerful arms lending themselves t 

 the full measure of arboreal progression. The gibbons ar 

 oriental In distribution, living In the wooded regions of south 

 eastern Asia and the Islands of Sumatra, Borneo, and Java. 



It were well to dwell for a moment upon the locomotiv 

 methods of these apes which. Instead of running upon th 

 upper side of the branches, as do most arboreal forms, swinj 

 beneath them by means of their hands. This method of locc 

 motion has been called brachlatlon (Lat. hrachium, arm) an* 

 In all probability took Its rise with the earliest anthropoids 



