96 MAN THE ANIMAL 



for the class. These absolute figures were then reduced to the 

 percentages shown in the table. Thus the first density class, 

 0-9 persons per square mile, includes 147 "political units" whose 

 aggregate area is over 29 million square miles. Even the highest 

 density class (3100 and over persons per square mile) with only 

 fourteen "political units" has an aggregate area of over 1200 

 square miles. 



The first and most striking general fact that is evident from 

 the table is the extreme skewness of the distribution of popula- 

 tion density over the earth's surface. Taking the mean densities 

 of the several classes as a conservative basis for estimating the 

 range of intensity of human crowding upon the earth it is seen 

 that about 36 per cent of the political units cover only 0.3 per 

 cent of the whole range of population densities; and even 

 77 per cent of the political units cover less than 2 per cent of 

 the total range of densities. 



This skewness has come about initially through the self- 

 interested desire, and eventually the social and economic neces- 

 sity for large numbers of people to live together in cities. This 

 process of urbanization down through the ages has led to the 

 formation of the great metropolitan centers, or "conurbations" 

 as Fawcett calls them, in which so large a proportion of present 

 day men live out their allotted spans. They represent one of the 

 many quaint ways in which mankind is coming to resemble 

 more and more clearly the termites in modes of life and social 

 philosophy. 



The matter may be looked at statistically in other ways that 

 do not involve consideration of the separate political units. Well 

 over a half (57 per cent) of the total land area of the earth is 

 occupied by only four and a half per cent of the total popula- 

 tion of the world. And about 81 per cent of the earth's total 

 land area contains only 18J4 P^r cent of the world's population. 

 Only a little over 5 per cent of the land area of the earth 

 (densities of 200 and above) contains nearly 52 per cent of its 

 population. 



Figure 19 emphasizes graphically certain broad facts of the 



