DOMESTIC MAMMAL ADAPTATIONS 



effect of civilization and becoming fit to follow "the call of the 

 wild," as Jack London would say. 



Between the immediate response of shivering and the long 

 term acclimatization of growing a thicker fur, there is an intermed- 

 iary adaptation. For some time the dog brought from the hot to the 

 cold environment would presumably respond with "insulative cool- 

 ing." He would let the temperature, especially of the outer layers 

 of his body, drop. Scholander (1958) discovered this temporary an- 

 swer to cold exposure in the Australian aborigines. This adapt- 

 ation is especially advantageous in climates with great diurnal tem- 

 perature changes. 



I remember Nansen's account of his polar expedition, especially 

 his description of Johansen's sleeping peacefully with his bare foot 

 stuck out from the tent into the subzero polar air. This observation 

 indicates that the Norwegian polar explorers may also have ac- 

 quired some ability to utilize insulative cooling. 



Social Temperature Regulation 



My account of adaptations to prevent a fall of body temperature 

 in a cold environment would not be complete without mentioning 

 social temperature regulation. Animals have learned to conserve 

 heat by "togetherness," also called "huddling." That this method is 

 effective has been shown in baby chicks, some of which were denied 

 fulfillment of their social instinct and were forced to burn up more 

 fuel to keep warm, while involimtarily practicing rugged individ- 

 ualism (Fig. 11). 



REGULATION AGAINST OVERHEATING 



An old method to get relief from too much heat is the use of a 

 fan. I am told that ladies used this instrument not only to increase 



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