274 THE PRESENT EVOLUTION OP MAN — PHYSICAL 



and disastrous experience of it are much more resistant 

 than those that have had little or no experience of it. 

 Even people who strenuously repudiate the idea of 

 evolution in general, must admit that in this case 

 evolution has certainly occurred ; for if, as they usually 

 believe, all the races of mankind had a common origin, 

 and were therefore originally alike, then in no other 

 way is explainable the difference that now exists 

 between one race and another; not only as regards 

 disease, but also as regards size, colour, shape, &c. — e.g. 

 between the Englishman and the West African negro. 

 The only question possible is as to how this evolution 

 occurred — as to what are the factors of it. Has it been 

 by the accumulation of inborn traits, or by the accumula- 

 tion of acquired traits, or by the accumulation of both ? 

 This question has already been dealt with ; there can 

 be no doubt that it has resulted solely from the accu- 

 mulation of inborn traits. 



But while this evolution, when once attention is 

 drawn to it, becomes so manifest, that we need not 

 waste time in marshalling in proof of it facts that are 

 notorious, we shall nevertheless find it interesting to 

 note how exactly the degree of evolution undergone by 

 any race coincides with the virulence of the disease to 

 which it has been subjected. This fact is admirably 

 brought out in the following — 



" In Ceylon there died of malarial fevers per 1000 of 

 the population — 



Plirsch, Geographical and Histmical Pathology, vol. i. p. 245, 



