A THEOR V OF RETROGRESSION 6i 



facts I have endeavoured to drive home have 

 been — (i) that characters acquired by the parent 

 are not inherited by the child; (2) that evolution 

 results from the stringent elimination of the unfit ; 



(3) that when the elimination which has caused 

 the evolution of any character, ceases, or nearly 

 ceases, that character undergoes degeneration ; and 



(4) that degeneration is due to atavism— to a pro- 

 cess of reversion which, step by step, retraces 

 the previous evolution till, if it be continued long 

 enough, that more or less remote ancestor is 

 approximated to in whom the character did not exist. 



We have seen in the preceding pages that 

 Natural Selection, the thing so often denied, 

 actually does occur in the only case in which we 

 are able to note its operations. We cannot tabulate 

 the death-rate of wild animals and plants, but we 

 are able to tabulate the death-rates of the races 

 of men, and to observe that under the influence of 

 Disease Selection the physical nature of mankind 

 is slowly altering towards a momentous conclusion. 

 But zymotic disease is not the sole selective cause 

 of human elimination. If we continue our study 

 of selective death-rates we shall find that a mental 

 alteration, in every way as momentous as the great 

 physical change we have chronicled, is at work, 

 slowly, but mightily, moulding the destinies of the 

 races of mankind. 



