NATURAL SELECTION AMONG CIVILIZED MEN 109 



of wild species to their environments is so close, the number 

 of the survivors compared with the total number of the off- 

 spring is so small, that probably the great majority of deaths 

 among them are entirely " haphazard." It was this fact that 

 caused Weismann to declare that no man had seen Natural 

 Selection at work, and the late Lord Salisbury, incited thereto 

 by theological preconceptions, to insist that Natural Selec- 

 tion was never at work. 1 It is this that has moved several 

 distinguished men of science to undertake prolonged and 

 laborious experiments to prove that Natural Selection is ever 

 at work. 2 



176. But we know man much better than any other animal 

 or plant. The peculiarities of every human being are, of 

 necessity, noted before his death by some of his contempor- 

 aries. His offspring and descendants are also under close 

 observation. For some thousands of years the chief causes of 

 mortality among his races have been studied with anxious 

 attention. During recent years very precise scientific methods 

 have been adopted. An army of trained and experienced 

 medical workers has delved in almost every nook and cranny 

 of the world, and in all civilized countries a government 

 department has tabulated the results of their labours. We 

 now know precisely the causes from which men die ; we know 

 approximately the number of deaths due to each cause, and 

 the average ages at which men die from this or that cause. 

 We have therefore ample materials on which to found a 

 judgment as to the effects produced on descendants, and 

 therefore on the race, by these precisely ascertained and 

 tabulated causes of elimination. 



177. In the great majority of instances men, especially civil- 

 ized men, perish of disease. Haphazard deaths, comparatively 

 speaking, are very rare. Moreover, where, as in all civilized 

 communities, men live in dense and settled masses, and so 

 can take disease from one another, the great majority of 

 deaths are due to zymotic diseases to diseases caused by 

 minute living beings belonging to various plant and animal 

 species. 



A mass of sorely neglected material for the study of 

 heredity has been accumulated by medical workers, which, 

 for volume and detailed accuracy, transcends by far anything 

 within the reach of zoologists and botanists. The medical 

 man spends his life in the study of parent and descendant. 



1 Presidential Address, British Association, 1894. 



2 For example, Professor Weldon's experiments on crabs, and Pro- 

 fessor Poulton's experiments on chrysalises. 



