IBVING 



in the Koyukuk Valley of interior Alaska just north of the arctic cir- 

 cle the lowest temperature during the mild winter of 1959 was -59 

 G, and the warmest day in June was +29 C. On April 3, -36 G was 

 recorded, and on April 11, the temperature rose to +13 G (U, S. 

 Weather Bureau, 1960). Residents of the Arctic encounter large an- 

 nual variations and precipitous rise of temperature in spring. 



Stable Physiology of Arctic Populations 



History indicates the presence of Eskimo people in the American 

 arctic for 1,000 years before the first Norse settlers described them 

 in southwest Greenland. Archaeological study of flint implements in- 

 dicates that an Eskimo type of culture has been in the American Arc- 

 tic for 2,000 years, and the ancestry of the Eskimo race in Alaska is 

 probably as old as the traces of its culture. The stability of these 

 people shows that their arctic existence was not uncertain and that 

 it was secured by good adaptation to arctic life. 



Relics of mammals indicate that species now living have been 

 stable in form for several hundred thousand years. In the last part 

 of this period drastic climatic changes have occurred; 6,000 years 

 ago the north was warmer than now, and some 20,000 years ago most 

 of Ganada and much of Alaska was thickly covered by great ice 

 fields. The ancestors of arctic animals have been exposed to pro- 

 nounced variations in climate during a few thousand years. Although 

 many generations succeeded each other in that time, the evolution of 

 new species is not apparent. The arctic species must have long pos- 

 sessed physiological characteristics which were adaptable without 

 evolutionary change inform to the recent climatic variations through 

 which they have successfully passed. 



Although relics of animals of the past provide little direct evi- 

 dence about their physiology, systematic comparisons of physiologi- 

 cal characteristics indicate that the principal mamm alian and avian 

 thermal processes have been stable since nearly the origin of the 

 warm-blooded habit. In arctic Alaska JohnKrogandl (1954) found a 

 fair sample of thefewspeciesof arctic mammals and resident birds 

 and observed that their body temperatures did not differ significantly 

 from those of animals of warmer climates. In fact among all of the 



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