344 ENVIRONMENT AMONG MEN 



more highly strung than m their native land. Clearly in some 

 fashion the nervous tone is injuriously affected by residence in 

 tropical climates. In a similar manner nervous tone is affected 

 by many elements in the envu'onment in civilized countries, 

 such as vibration, noise, and so on, leaving aside the effect of 

 food, drink, and disease. To the importance of disease in this 

 respect we shall return later. As regards noise, vibration, and so on, 

 but little is known — their influence being possibly considerably 

 greater than is usually suspected. 



5. Ellsworth Huntingdon has in recent 3^ears in a number of 

 publications elaborated a theory according to which climate has 

 been one of the main factors in determining where civilization 

 shall develop and flourish. As this theory depends upon the 

 supposed direct influence of the environment on man, it may 

 be noticed here. He has made observations which are interpreted 

 as showing that there are optimum climatic conditions under 

 which the maximum energy is exhibited. These conditions arise 

 when the average temperature of day and night together lies 

 between 58° F. and 71° F. and when there is a certain degree of 

 moisture. His observations, made in America, were based on 

 the output in piece-work factories and on similar data and tend 

 to show that not only do all European races, including the Finns, 

 display most energy under these optimum conditions, but also 

 the Japanese and the negroes. He then proceeds to show 

 that where these optimum conditions prevail in the world, there 

 to-day are to be found the highest forms of civilization. Upon 

 these data he raises a very far-reaching theory to the effect that 

 throughout history civilization has arisen and flourished only 

 where there has been an approximation to these climatic con- 

 ditions. To the obvious difficulty that former civilizations have 

 often flourished in countries the climate of which at the present 

 day is far from these optimum conditions, he replies that climate 

 has changed, a theory which he has for some years strongly 

 advocated.! 



It may be said that there is nothing novel in the idea of 

 optimum climatic conditions.^ In the previous section it was 

 pointed out that Europeans in tropical climates suffer from 



1 Huntingdon, Civilization and Climate. See also the same author's ' Climate 

 and Evolution of Civilization ', in Evolution of the Earth and its Inhabitants, edited 

 by Lull. * Thus Montesquieu remarked upon the fact that greatest vigour 



is found in the colder climates {Esprit des Lois, Part III, Bk. XIV, ch. ii). 



