THE TRENDS OF EVOLUTION 177 



ence of the societies of man. Trends are nature's long con- 

 tinued organizing drives. Those to be discussed in this chapter 

 include the trend toward increasing size and complexity of 

 organisms; the trend toward greater social life, a rising func- 

 tional interdependence and consequent necessity for mutual 

 aid; the great trend toward cephalization (formation of a 

 head), and finally the dominance of mental life; and one that 

 is most peculiar to man, the trend toward neuro-linguistic pat- 

 terns of behavior, and the consequent necessity for the use 

 of scientific methods of reasoning and the application of the 

 principles of semantics. 



At first glance it would not seem that size is a major trend 

 of great importance; and yet increase in size, after the mi- 

 croscopic beginnings of life, was absolutely necessary to 

 higher levels of mind. Increase in size came not to the cell as 

 a single unit, but through the union of cells to form organ- 

 ized groups with an eventual division of labor. The size of 

 the cellular unit is limited by the need of a proportionately 

 high ratio of absorbing surface, a ratio much too high to per- 

 mit any but minute individuals at the cellular level. These 

 minute beings (amoeba is one) do quite well adaptively— so 

 well, in fact, that we cannot say that man is a higher animal 

 merely on the basis of an increased complexity in structure. 

 Amoeba carries on all of the activities of living (metabolism) 

 without any fuss and without calling upon elaborate gadgets 

 and organs to help out. Respiration, circulation, locomotion, 

 ingestion, digestion, excretion, growth, and reproduction 

 occur within a single unit, one one-thousandth of an inch in 

 diameter. 



The question has often been raised in biology as to 

 whether one is justified in assuming that the increase in size 

 and complexity constituted progress? In the literal sense the 

 answer is, no. Amoeba adapts as well as man and even has 

 certain advantages in that it is not encumbered with com- 

 plex organ-systems that can get out of order without too 

 much provocation. Its simple reproductive procedure, the 



