EXPLANATION OF PROGRESS 533 



preceding the first making of permanent records. We 

 know that very early in historic time men lived who 

 were in all probability fully equal to modern man, not 

 only in physical power, but in intellectual ability and 

 emotional characteristics as well. This leads to the con- 

 clusion that the progress of humanity in historic and 

 late prehistoric time has not been due to racial develop- 

 ment, but rather to the utilization of qualities which were 

 possessed by primitive man equally with modern man. 



Explanation of Progress. — The explanation of 

 progress is to be sought in some qualities which man 

 possesses and which other animals do not, since it is clear 

 that if the other animals were in possesssion of the same 

 or of similar qualities they would show the same 

 ability. Human and animal characteristics have been 

 classified as physical, intellectual, and emotional. In 

 these three realms are to be sought the special properties 

 which have formed the basis of human progress. 



Physical Characteristics. — Notwithstanding man's 

 marked physical similarity to the other mammals, his 

 body presents two special features which undoubtedly 

 have contributed to his achievements. The first of these 

 is the erect posture. It is characteristic of man that he 

 alone among animals stands definitely upon two feet and 

 performs the major part of his locomotion with the lower 

 limbs only. The advantage that this confers upon him 

 is chiefly in the release of the front limbs from locomotor 

 duty and in thus freeing them for use as organs of touch 

 and for carrying on the grasping function. It is quite 

 true that many other kinds of animals use the front 

 limb, sometimes to a large extent, as an organ of touch 

 and of grasping, but only in man are these the primary 

 functions, and locomotion the secondary. In all other 

 mammals locomotion is the primary function of the 

 front limb, other functions being only incidental. 



The second significant physical difference between man 

 and other animals is in the superior flexibility of the 



