THE EVOLUTION OF MAN 



of the bird developed out of the scale of the 

 lizard. But it seems quite improbable that either 

 a scale or a feather should have been transformed 

 to such an extent as to assume the characteristic 

 form of hairy covering typical of mammals. 

 Scales, as well as feathers, have evidently been 

 from the very beginning essential means of pro- 

 tecting the skin, either in defense against 

 enemies, or in the case of birds, against the in- 

 clemencies of the weather. We observe that 

 scales serve that purpose occasionally even in 

 mammals, for instance, among armadillos. Some 

 whales likewise possessed something like that in 

 former times. But the typical covering of the 

 skin of mammals consists of hair. And it seems 

 that originally hair had nothing to do with pro- 

 tection such as is afforded by scales or feathers, 

 but rather served a wider purpose, embracing not 

 only protection but essentially feeling. The first 

 hair consisted of very fine feelers and performed 

 the functions of touch for the skin. It was not 

 until later on, when mammals acquired warm 

 blood, that hair assumed also the role of a non- 

 conductor of heat. 



Now when we look about us to find the be- 

 ginnings of sense organs of the skin which might 

 have developed into hair, for instance, among 



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