IV 

 THE POPULATION PROBLEM AMONG MEN 



1. It has been shown in the last two chapters in what the 

 population problem among species in a state of nature consists. 

 With regard to the quantitative aspect in particular it has been 

 showTi that among such species mental evolution, greatly as the 

 stage reached differs between the lowest and the highest forms, 

 has not attained a point at which the essential features of the 

 position have in consequence been affected. Enough has been 

 said to show that in the case of the most primitive races of man 

 now living mental evolution has reached a point in consequence 

 of which the quantitative problem has assumed a totally different 

 aspect. 



With regard to the qualitative problem the question also arises 

 as to how far mental evolution in man has affected the position. 

 In one very important respect mental evoli^ion has wholly altered 

 the position of man as regards this aspect of the problem, as it has 

 regarding the quantitative aspect. How this has come about may 

 be considered after it has been observed that mental evolution 

 has also been the cause of other changes which, while they do not 

 alter the fundamental position of man as regards the qualitative 

 aspect, yet are of great importance. 



As we have seen among species in a state of nature change is 

 founded upon germinal change. So, too, among men there is 

 germinal change, and so far as history (using the term in the 

 widest sense to include what is often rather meaninglessly called 

 ' prehistory ') is connected with germinal change, so far it is of 

 essentially the same nature as change among other species. But 

 both the direction and intensity of germinal change among men 

 have been greatly influenced by mental evolution. Certain causes 

 of elimination have been removed wholly or in part, others have 

 been introduced. The facts are familiar ; there is no need to 

 labour the point. It is also worth noting that, should it be found 

 that mutation frequently arises owing to alterations in the environ- 

 ment during the formation of the germ cells, such a discovery 



