ENVIRONMENT AMONG MEN 337 



physical characters. The aggregation of men into towns involves 

 exposure to smoke, noise, and vibration among other factors. 

 Modern industrial conditions in particular expose workers to 

 varied surroundings. Human diet has become equally varied. 

 The cooking of food was an innovation involving great changes 

 in the factors which play upon the digestive organs. Innumerable 

 animals and plants have been drawn upon by man as food. 

 Perhaps more important than the variations in what man eats 

 are the variations in what he drinks. Under the heading of use 

 come all those habits such as reading, washing, smoking, and 

 shaving. Various occupations bring with them various degrees 

 of muscular activity or involve its reduction to next to nothing. 

 There are various modes of riding and various ways of sitting. 

 Lastly the prevalence of disease has introduced another factor 

 which has a profound influence upon mental and physical 

 characters. 



This varying of the environment has come about gradually, 

 slowly at first and with increasing speed latterly, until at the 

 present day, of four men having their homes in the same town 

 one may do clerical work involving no exercise, another may 

 labour in a cotton mill where it is warm and moist, a third may 

 perform hard physical labour in a mine in semi-darkness where 

 the air is full of a particular kind of dust, and a fourth may work 

 on board ship exposed to all the rigours of the Atlantic. To such 

 differences may be added all the differences between meat-eaters 

 and vegetarians, smokers and non-smokers, alcoholic drinkers 

 and abstainers, and so on. Contrast the variations in the environ- 

 ment of modern man with the variations in the environment of 

 any species in a state of nature and it will be apparent why it was 

 said above that the relation of man to his environment was clearly 

 distinguishable from that of any species in a state of nature to its 

 environment. 



We are about to consider in this chapter the influence of the 

 environment upon the physical basis of life ; we shall be concerned, 

 in other words, with its function as the complement of the germinal 

 constitution. The discussion will be limited to the notice of such 

 factors as are in operation ; of the possible effects of the environ- 

 ment there is no need to speak. From two other points of view 

 also the environment is of importance ; as a factor in selection 

 it will be considered in Chapters XVII and XVIII ; as the subject- 



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