CHAPTER XIII. 

 HUMAN POPULATION IN THE FUTURE. 



§ 371. Any further evolution in the most-highly evolved 

 of terrestrial beings, Mun, must be of the same nature as 

 evolution in general. Structurally considered, it may consist 

 in greater integration, or greater difi'erentiation, or both — 

 augmented bulk, or increased heterogeneity and definiteness, 

 or a combination of the two. Functionally considered, it 

 may consist in a larger sum of actions, or more multiplied 

 varieties of actions, or both — a larger amount of sensible and 

 insensible motion generated, or motions more numerous in 

 kind and more intricate and exact in co-ordination, or 

 motions that are greater alike in quantity, complexity, and 

 precision. 



Expressing the change in terms of that more special 

 evolution displayed by organisms ; we may say that it must 

 be one which further adapts the moving equilibrium of 

 organic actions. As it was pointed out in First Principles, 

 % 133, "the maintenance of such a moving equilibrium, re- 

 quires the habitual genesis of internal forces corresponding 

 in number, directions, and amounts to the external incident 

 forces — as many inner functions, single or combined, as there 

 are single or combined outer actions to be met." And it 

 was also pointed out that " the structural complexity accom- 

 panying functional equilibration, is definable as one in which 

 there are as many specialized parts as are capable, separateljr 



