May, 1922 common misconceptions of evolution 175 



amusing were it not for the fact that it shows such a deplorable 

 state of ignorance among our supposedly enlightened people, 

 with regard to the progress of science. 



It is true that many otherwise highly educated persons do 

 not have a very clear idea of the law of evolution and that 

 many misconceptions are current among them. In the effort 

 to clear up some of these mistaken notions let us consider 

 a few of those which appear to be most commonly held. 



It is commonly, but mistakenly, supposed that scientific 

 men are divided in opinion as to the truth of evolution. This 

 idea has arisen from the discussion of certain minor matters, 

 or side issues, such as the mode of origin of species. It may be 

 safely stated that the only questions concerning evolution that 

 are debated by the biological scientists, are those that have 

 to do with the method of evolution — the discussion of the means 

 employed by nature in causing the changes that are admitted 

 to have taken place, and the paths along which the advance- 

 ment occurred. Though there is still much discussion as to 

 just how it has come about, no scientist at the present time 

 has any doubt of the fact of evolution. Furthermore, all will 

 admit that three great interacting factors are to be found in 

 variation, however it may be caused; in selection, by which 

 inadaptive changes are eliminated and adaptive changes 

 permitted to continue; and in heredity, by which any advance, 

 involving the constitution of the organism, may be perpetuated 

 through succeeding generations. 



Variations of some sort are necessary, of course, however 

 they may be caused, or there could never be any change and, 

 without change, naturally, no evolution. Moreover, the varia- 

 tions must be of a particular class, for they must be inheritable, 

 and, as far as we know, only those variations are capable of 

 being inherited which involve a change in the germ plasm. 

 The "discontinuous variations" of Bateson and the "muta- 

 tions of DeVries are the most marked of these germinal varia- 

 tions, but just how small a variation may be and still be 

 inheritable no one has yet discovered. Variation, then, 

 supplies the crude material for evolution. 



Natural selection, that much misunderstood and much 

 abused term! — selection is merely another way of stating the fact 

 that variations of all sorts occur and that some of these may 

 benefit an organism, while some others may be harmful to it. 



