98 HOMOIOTHERMISM 



on the human race and man does his best work where 

 such variations obtain (Huntington, 1915). Thus, 

 though man strives in general to make liis physiologic, 

 psychic, and economic conditions for living as uniform 

 and dependable as possible, he does not reach his great- 

 est degree of accomplishment in monotony. 



Frigid and Tropical Regions. — The frigid regions of 

 the earth produce little on land, but the sea has long 

 been exploited for its food resources. The tropics have 

 not been the seat of much human achievement. There 

 are perhaps several reasons for this, but two are note- 

 worthy: (1) hot, monotonous climate and (2) disease. 

 The humid tropics, though often producing an abundance 

 of plant and animal life, have never been the environ- 

 ment for the highest types of civilization. The charac- 

 teristic racial stocks in tropical countries are Negroids, 

 Malays, Mongolians, and Semitics. With the clearing 

 up of tropical diseases, Caucasians are dominating tropi- 

 cal countries more and more, but Caucasians as a rule 

 do not flourish in the tropics. Perhaps it will be best 

 for the world to leave the tropics as the home of com- 

 paratively primitive, simple people who will work for 

 low wages and furnish raw materials for the more aggres- 

 sive and progressive peoples in temperate zones. There 

 is no question but that the dark-skinned races are more 

 healthful than Caucasians in warm countries. 



There are certainly racial peculiarities which make 

 some types of men better adapted to certain climates 

 than others. White men who go from temperate to trop- 

 ical countries show reduced basal metabolism (Knipping, 

 1925; Fleming, 1925). Native inhabitants of the tropics 

 have a lower blood pressure than people who have re- 

 cently come from temperate regions (Cadbury, 1923). 

 There are fundamental differences in metabolism be- 



