1870.] Notices of Scientific Works. 375 



men do not struggle for existence — that is assured to them by 

 society — they struggle " to get on." This is practical Darwinism, 

 and the author shows that the expenditure of brain-power in man's 

 case affects the potential duration of his life. He reviews carefully 

 the phenomena bearing on this aspect of the question on savage 

 and civilized life, and his conclusion is, " that a civilization of the 

 highest order in which the efficiency of the community and the 

 efficiency of the component individuals is greatest — in which there 

 is the most harmonious action, the greatest happiness for the 

 greatest number, the least excessive expenditure with " the least 

 luxury, where regularity and temperateness are innate character- 

 istics, will be that state of civilization most favourable to lon- 

 gevity." 



But there is a set-off against this : great thinkers do not live so 

 long as those who take things more easily, and we find from his 

 tables that less distinguished men in every profession enjoy longer 

 lives (in one sense of the word " enjoy ") than those who are more 

 distinguished. If the millennium were reached, "men would no 

 longer die of disappointment, but would all attain 80 or 100 years. 

 There is no apparent reason why longevity should not increase 

 beyond that limit, and advance with advanced evolution, and the 

 diminished expenditure implied in complete adjustment" (p. 128). 

 There is, however, another matter to be considered : Will not the 

 limited area of our globe be pretty well covered with human deni- 

 zens before that happy day dawns upon us ? and what then ? 

 However, that is a matter for posterity to consider ; and meanwhile 

 we cordially recommend Mr. Lankester's suggestive little volume to 

 our biological readers. 



