THE ERA OF HELPLESSNESS 31 



cumstance emphasizes the vast difference which the 

 modification of the entocuneiform bones produced, 

 in the adaptation to standing, walking, or running 

 in the upright attitude. 



The angular inclination of the longitudinal axis 

 of the head towards the vertebral column depends 

 on the location of the center of gravity of the head 

 and the place where the spinal cord passes through 

 the bony plates of the skull. This opening is called 

 the occipital foramen magnum. 



In the human body it is situated a little back of 

 the center of the base of the skull, so that only when 

 the body is in the erect attitude can the head be 

 easily supported without conscious muscular effort. 



This is another reason why, after the variation in 

 the entocuneiform, our brute ancestors adjusted 

 themselves quickly to physical uprightness. 



These two, then, the modification in the entocunei- 

 form bone and in the position of the foramen mag- 

 num, are the Physical Basis of Civilization indicated 

 by the title of these essays. Until they had occurred, 

 natural selection among sentient creatures was 

 mainly instumental in securing the survival of the 

 strong, cunning, greedy, fierce, and cruel. For the 

 low type of mind with which the most intelligent 

 animals below man are endowed is inadequate to 

 anything higher than obtaining for its possessors in 

 the general struggle for existence with living an- 

 tagonists the largest attainable share of the supplies 

 and opportunities provided by unaided nature. 



