CAN WE SEE EVOLUTION OCCURRING?
By Herbert Spencer Jennings
Professor of Zoölogy, The Johns 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 continuing 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, transform repeatedly, until from one or a few types many would be produced. You would get dissolving views of amoeba transforming 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 movement so slow that it requires 25,000 years to go once around
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