94 MAN THE ANIMAL 



first instance with the discovery and rapid improvement of 

 practical steam engines. In generalized terms what expanded 

 man's effective universe, and made possible a great spurt of 

 population growth was scientific discovery and the application 

 of its results, in the broadest sense including exploration as 

 well as technology, to man's basic problem of how best to cope 

 with and exploit his natural environment. 



To this day, peoples who because of geographical location, 

 climatic conditions, general stupidity, and other causes, have 

 been unable to participate in any real sense in the consequences 

 of an expanding effective universe, are still growing in popula- 

 tion verp slowly, if at all. The conditions of living, and particu- 

 larly the difficulties of getting a living, in the more primitive 

 stages of culture where the individual wrings his living out of 

 a raw and untempered environment by his own direct efforts, 

 do not permit rapid population growth any more now than 

 they ever did. 



IV 



The most obvious direct and objective consequence of the 

 great spurt of world population growth that has occurred in 

 the last 300 odd years is the increase in average density of 

 population that it has entailed. It will be well to examine the 

 facts about this in some detail. 



The population of the earth is distributed with great uneven- 

 ness over its land surface. This is shown in Figure 18. 



This table is arranged in order of ascending density classes 

 (persons per square mile). It is based upon 906 separate po- 

 litical or administrative units for which separate data are avail- 

 able as to area and population. By "political unit" is meant 

 either a country, or a state, or a department, or a canton, or a 

 colony, protectorate, or territory, or in a few cases a city having 

 separate administrative status equivalent legally and politically 

 to that of a state. Each such separate political unit was put in its 

 appropriate density class and the areas and populations summed 



