80 MAN THE ANIMAL 



basis, in all types 50 per cent of the total falls in our worker 

 group aged 15 to 49 inclusive, while in the progressive type 

 of population the percentages of infants and senescents are 

 respectively 40 and lOj in the stationary type 33 and 17 j and 

 in the regressive type 20 and 30. These are, of course, arbitrary 

 figures but in a general way do correspond with reality. From 

 the point of view of population growth Brazil, India, and the 

 Argentine are in the progressive state, while England, France 

 and Sweden are in the regressive state. 



We must stop at this point, but perhaps enough has been said 

 to make it plain that man's life span, and its prolonged periods 

 of infancy and senescence, are of great potential importance in 

 connection with his sociality, and human biology generally. 



