242 PROBLEMS OF HUMAN EVOLUTION 



roughing, often including a very meagre diet, to which their 

 grandfathers and even their fathers submitted as a matter of 

 course, is now an impossibility ; it is not merely that we 

 choose to manage things differently. In their present com- 

 paratively luxurious environment they develop great vigour, 

 and, to attempt a rough approximation, it cannot be said that 

 there is any falling-ofF in the stronger 80 per cent. The 

 change is in the conditions that seem necessary to maintain the 

 vigour of all but a not very large percentage. 



But since civilised society is an organism that is perpetually 

 renewing itself from its base, the phenomenon does not neces- 

 sarily imply degeneration. The conclusion we draw from it 

 must depend on the depth to which the tendency penetrates. 

 Is comfort beyond what was known fifty years ago a necessity 

 to the uppermost strata of society only, or to the lower strata 

 also ? and here the answer is easy ; the average standard of 

 life has risen, and what were luxuries are becoming necessi- 

 ties. True, in some parts of Great Britain, notably in the 

 most crowded parts of big towns, there is a high rate of 

 elimination and race vigour is being maintained. But this is 

 hardly likely to continue. The lower strata of society, the 

 great recruiting ground of the upper, are undergoing the same 

 softening process. We are, in fact, using up our physiological 

 capital very rapidly, and we should be very foolish to let the 

 maintenance of stature or even an increase of the stature actual- 

 ised blind us to the fact. 



Ill 



DISEASE 



Part All species that survive, survive by adapting themselves to 

 played by fa e ' ir environment. Bearing this in mind during our discussion 



disease in . 



evolution of the question or degeneracy, we may divide diseases into two 

 classes : those that doctors are successful in dealing with and 

 those which, in spite of medical skill, often prove fatal. The 



