74 PHYSICAL BASIS OF CIVILIZATION 



strikingly impressive by the fact that the bodily 

 parts above indicated interact and co-operate with 

 arms, hands, thumbs, fingers, limbs, feet, and toes. 



The creatures below man can, on the contrary, 

 only respond by conduct to comparatively few gen- 

 eral and fundamental demands made on them by 

 the environment, such as recur with comparative 

 regularity and frequency, to which they attempt to 

 adjust themselves by defense, flight, pursuit, retire- 

 ment to shelter, etc. Nor is the high degree of 

 adaptability of conduct possessed by man required 

 in their case. For their bodies are supplied with 

 natural coverings, which change in density to corre- 

 spond with the variations in the climates of their 

 habitats. Besides this, they are supplied with 

 natural means of offense, defense, and escape, and 

 therefore susceptible to only a minimum of risks 

 as compared with the maximum to which brute-man 

 was exposed. 



For these reasons did the survival of the two- 

 footed brute depend, from the very beginning, much 

 less on the natural physical adaptation of his organ- 

 ism, but much more on the adjustment of his conduct 

 to those changes, both great and small, in the con- 

 stantly varying order of the environment which 

 occur from moment to moment. Conduct such as 

 this cannot be accomplished by creatures less fitted 

 than man for an almost infinite variety of compound 

 concerted movements. 



Before the bearing of the above considerations 



