HUMAN ORGANIC EVOLUTION: FACT OR FANCY? 



the very fact that we had to list four separate forces which 

 produce frequency changes in the evolutionary process sug- 

 gests that an understanding of their interrelations though 

 appreciated is not well integrated. But integration has begun, 

 as for instance in the calculations of gene equilibrium in small 

 populations, which takes into account both rates of selection 

 and mutation, and size of population. No general integration 

 has been accomplished, and there are also problems not only 

 with the mathematics of the problem, but also with experi- 

 mental data. Nevertheless, progress is being made in the 

 direction of bestowing unity on the theory of evolution, as was 

 pointed out earlier. This much seems certain, the various 

 explanations given above seem to harmonize with one another 

 and are not contradictory, though lacking in a total com- 

 prehension. 



Simplicity of a theory means that theoretically certain 

 phenomena can be expected to happen, or that such and such 

 was a likely way in which it may have happened. Evolutionary 

 theory seems to do just that, and in so doing undoubtedly 

 oversimplifies natural processes. But it provides an approxima- 

 tion which greatly facilitates not only discussion of the 

 problems involved, but also understanding of the problem. 

 It does not mean that the explanation has to stay at this level. 

 Rather as knowledge deepens, there is a good chance that the 

 theory becomes more complex, as in fact the history of 

 evolutionary theory already demonstrates. At the same time, 

 the theory has becomes more sophisticated, and in terms of 

 the criterion above, more elegant, even without all-encom- 

 passing mathematical formulae. 



Is then evolution fact or fancy? From what has been said, 

 the question seems to be a spurious one. There are the facts 

 of change, the facts of variability of organic forms, and there 

 is the undeniable fact of the great antiquity of some simple 

 forms. Unless one wants to go back to the days of the "special 

 creationists" these facts must be interpreted in some such 

 fashion as was indicated above. But it must be kept in mind 

 that this is an explanation. There may be others forthcoming. 

 But the weight of evidence at this time seems to favor such 

 an explanation. It was impossible to list here all the evidence, 

 such as the embryological, or much of the work now done in 



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