CAN WE SEE EVOLUTION OCCURRING? 

 By Herbert Spencer Jennings 



Professoy of Zoology, The ]ohns Hopkins University 



The doctrine of organic evolution is the doctrine that 

 animals and plants are slowly transforming, producing new 

 kinds; that they have done this in the past and are con- 

 tinuing to do it now. It does not deal with something 

 transcendental, something metaphysical; it deals with 

 processes as real as the running of a stream or the growth 

 of a tree. Organic evolution, then, is a physiological process, 

 like the digestion of food; it is something that is occurring 

 at all times, including the present. The doctrine of organic 

 evolution means simply that if you lived long enough you 

 would see organisms begin as simple creatures, change shape 

 and structure as a growing plant does, become diverse, trans- 

 form repeatedly, until from one or a few types many would 

 be produced. You would get dissolving views of amoeba 

 transfonning to creatures having more definite structures 

 and greater complexity; of Hipparion becoming a horse; 

 of an ape-like creature becoming a man. 



But no one can live long enough to see all that. The 

 process is too slow. Within the life of a man, or of many 

 successive men, very little alteration can be expected. Yet 

 men have detected and measured other slow things. The 

 earth's pole swings about in a small circle with a move- 

 ment so slow that it requires 25,000 years to go once around 



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