\ 



( 



IS ARBOREAL MAN 



pation of the fore-limb before the limb had lost any of 

 its possibilities of mobility' . This we have done because 

 of the knowledge that once the limb has become a sup- 

 porting organ, and given up its birthright of mobility for 

 the acquired stability, no subsequent degree of liberation, 

 due to altered habits, will achieve the same great possi- 

 bilities in evolution. Animals have liberated fore-limbs 

 already made stable, or partially stable, and they have 

 not attained the great results which we shall follow in the 

 stock we have been picturing. It is thus with the jumping 

 animals we have mentioned previously. The liberation 

 of the fore-limb may be ver^^ complete, but it i^ a fore- 

 limb of restricted possibilities that has been liberated. 



The arboreal habit alone is not the talisman; other 

 mammalian stocks have taken to an arboreal habit ; l)ut 

 they have taken to it after varied periods of quadrupedal 

 life. Thev have taken to it too late to derive the full 

 benefits from it, for they took to it with the fore-limbs 

 already dej^rived of some of their inherited mobility. 

 Such animals never become jDerfect tree-climbers. They 

 may acquire an extraordinary skill in running about the 

 branches of trees as many Rodents do, or they may even 

 climb in the proper sense of the word, but in this climbing 

 the grip is not obtained by the application of the palmar 

 surface of the hand, but by the hook-like action of claws 

 and nails; this method is practised by many of the Car- 

 nivora. The maximum of possibilities is not attainable 

 in any of these cases. It is not enough to have a thor- 

 oughly emancipated fore-limb, it is not enough to be 

 thoroughly arboreal. It was a combination of seemingly 

 humble and unimportant circumstances, acting at the 

 very dawn of mammalian life, which permitted the eman- 

 cipation of an unmodified fore-limb in a certain stock, 

 and so laid the direct path for the evolution of the highest 

 Mammals, and Man. 



