Chap. IV.] MANNER OF DEVELOPMENT. 137 



arms free and to stand firmly on his feet, of which there 

 can be no doubt from his preeminent success in the battle 

 of life, then I can see no reason why it should not have 

 been advantageous to the progenitors of man to have be- 

 come more and more erect or bipedal. They would thus 

 have been better able to have defended themselves with 

 stones or clubs, or to have attacked their prey, or other- 

 wise obtained food. The best-constructed individuals 

 would in the long-run have succeeded best, and have sur- 

 vived in larger numbers. If the gorilla and a few allied 

 forms had become extinct, it might have been argued with 

 great force and apparent truth, that an animal could not 

 have been gradually converted from a quadruped into a 

 biped ; as all the individuals in an intermediate condition 

 would have been miserably ill-fitted for progression. But 

 we know (and this is well worthy of reflection) that sev- 

 eral kinds of apes are now actually in this intermediate 

 condition ; and no one doubts that they are on the whole 

 well adapted for their conditions of life. Thus the gorilla 

 runs with a sidelong shambling gait, but more commonly 

 progresses by resting on its bent hands. The long-armed 

 apes occasionally use their arms like crutches, swinging 

 their bodies forward between them, and some kinds of 

 Hylobates, without having been taught, can walk or run 

 upright with tolerable quickness ; yet they move awk- 

 wardly, and much less securely than man. We see, in 

 short, with existing monkeys various gradations between 

 a form of progression strictly like that of a quadruped 

 and that of a biped or man. 



As the progenitors of man became more and more 

 erect, with their hands and arms more and more modified 

 for prehension and other purposes, with their feet and legs 

 at the same time modified for firm support and progres- 

 sion, endless other changes of structure would have been 



necessary. The pelvis would have had to be made broader, 



7 



