PRIMEVAL MAN 219 



men were good artists, and carved spirited 

 figures of mammoth, rhinoceros, bison, horse, 

 reindeer, and bear on ivory, or on the walls of 

 caves. The big Hon-Uke cats appear only 

 rarely in these pictures. 



In most cases the arctic and warm-temperate 

 or near-tropical animals supplanted one another 

 only incompletely as the waves of life advanced 

 and receded when the climate changed. This 

 seems a rather puzzling conjunction. The ex- 

 planation is twofold. When the climate changes, 

 when it becomes warmer, for instance, northern 

 creatures that once were at home in the low- 

 lands draw off into the neighboring highlands, 

 leaving their old haunts to newcomers from the 

 south, while nevertheless the two faunas may 

 be only a few miles apart; just as in Montana 

 and Alberta moose and caribou in certain places 

 were found side by side with the prongbuck. 

 Moreover, some species possess an adaptability 

 which their close kin do not, and can thrive 

 under widely different temperature conditions. 

 A century ago the hippopotamus was found in 

 the temperate Cape Colony, close to mountain 

 ranges climatically fit for the typical beasts of 

 north -temperate Eurasia. In Arizona at the 

 present day mammals and birds of the Canadian 

 fauna live on the mountain tops around the 



