540 HUMAN BIOLOGY 



The original table provides the following information: 

 The births, number of children born, and living, and average 

 number born and hving to mothers of 1923, by occupation 

 and age of father The occupations of the fathers are grouped 

 into the following main classes, with a number of smaller 

 subdivisions in each main class: 



1. Agriculture, forestry, and animal husbandry. 



2. Extraction of minerals. 



3. Manufacturing and mechanical industries. 



4. Transportation. 



5. Trade. 



6. Pubhc service (not elsewhere classified). 



7. Professional service. 



8. Domestic and personal service. 



9. Clerical positions. 



When one considers carefully the subdivisions under 

 these nine main heads the usual difficulty with official vital 

 statistics is at once encountered. Economically and socially 

 differentiated groups are included in some particular general 

 class from the remainder of which they are, in these respects, 

 sharply set apart, in reality. But it is reasonably obvious 

 that economic and social factors and forces are among the 

 most important elements in determining the biologically 

 significant environment of human beings, as they exist 

 here and now. Relative wealth virtually determines the 

 character of the immediate physical environment in which 

 men live. Furthermore, economic and social position are 

 significantly correlated with the amount of physical labor 

 which individuals perform, and this has been shown (Pearl, 

 1924, Chap, xi) to be biologically important. 



In view of these considerations it was deemed necessary 

 to reconstitute the main occupational classes, as given in 

 the original document cited, so that they might conform at 

 least somewhat more closely to significant reality. The 

 general plan followed in this reconstitution of the classes 

 has been described in detail (Pearl, 1927a) and need not 

 be repeated here. The net upshot of the manipulation is to 

 leave all the main occupational classes except 7 (professional 

 service) composed chiefly of laborers, more or less skilled, 

 but still persons whose living depends upon the daily 



