56 EVOLUTION OF THE HUMAN EYE 



of all apes, and from this would arise a desire for investi- 

 gation. It must have been the overpowering influence of 

 such a desire which induced man's ancestors to descend 

 from the safety of the branches to explore the earth beneath, 

 and thereby encounter new and unknown dangers. The 

 appetite for exploration and research, thus started, grew 

 by what it fed on, and continues to grow even up to the 

 present time. 



