2 2 RETROGRESSIVE DEVELOPMENT IN NATURE. [IX. 



efficient organs. In this respect civilization has caused de- 

 generation in us, by means of Panmixia, owing to the fact that 

 the well-being of individuals no longer depends upon the 

 highest possible development of their sense-organs. At the 

 present day we are able to make a living equally well, whether 

 our sense of hearing or smell is delicate or the reverse, and 

 even keenness of sight is no longer of decisive importance to 

 us in the struggle for existence. Ever since the invention of 

 spectacles, short-sighted persons— in the higher classes at any 

 rate— experience hardly any greater difficulty in getting a 

 living, than that endured by people with keen sight. In former 

 times a short-sighted soldier or general would have been a 

 sheer impossibility, and so would a short-sighted hunter : in all 

 grades of society short sight used to be a very real disadvantage 

 and an almost complete bar to advancement of an}'- kind. This 

 is no longer the case now ; a short-sighted man makes his way 

 in life as successfully as any other, and his defect, if congenital, 

 will be transmitted to his children, and will therefore tend to 

 make hereditary short sight commoner among certain classes. 

 Of course short sight may also be an acquired character, and 

 in such cases it is, I venture to affirm, not transmitted. But I 

 believe that the great prevalence of short sight is not only due 

 to the injuries acquired by over-straining the eyes and con- 

 tinualty looking at near objects, but also to Panmixia, or cessa- 

 tion of the action of natural selection, — a law to which we are 

 naturally subject in common with other animals. 



Much might be said of the effects of civilization in causing 

 physical degeneration, which indeed appears to be on the 

 increase. Consider for a moment the teeth : the art of dentistry 

 has been brought to such a pitch of perfection, that artificial 

 teeth are now almost to be preferred to natural ones. At any 

 rate no one need die now from insufficient nourishment in 

 consequence of the inability to masticate food, and there is 

 nothing to prevent the transmission of a predisposition to bad 

 teeth to any number of descendants. 



Nevertheless we need not fear that civilization will ever lead 

 to utter degeneration in man. The antidote is to be found in 

 the very process which causes the first deterioration of an 

 organ ; for obviously such deterioration can only continue as 

 long as it is not injurious to the individual in the struggle for 



