CHAPTER VI. 



PSYCHOZOIC EEA. AGE OF MAN". 



IN all previous ages there ruled brute force and ferocity. 

 In this age alone Reason appears as ruler. The order of 

 Nature must be adjusted to this keynote. Therefore, the 

 great ruling mammals of the previous age must become 

 extinct, and the mammalian class must become subordi- 

 nate ; noxious animals and plants must diminish, and 

 useful ones be preserved. 



Although in length of time this is not to be compared 

 to an era, nor to an age, nor to a period, nor even to an 

 epoch, yet it deserves to be made one of the primary 

 divisions of time, not only on account of the dignity of 

 man, but also,, and mainly, because through his agency 

 there is now going on in organic forms a change as sweep- 

 ing as any which has ever taken place. This change has 

 been going on ever since the introduction of man, and is 

 going on now, but will not be complete until civilized 

 man occupies the whole earth. 



It is interesting to mark some of the steps of this 

 change. The disappearance of the mammoth, the mas- 

 todon, the cave-bear, and the saber-toothed tiger was 

 due, partly at least, to man. These are among the first. 

 Some of the gigantic oxen of Europe (urns) lingered 

 until Roman times. One species (aurochs) still lingers, 

 being preserved by royal edict in the forests of Lithuania. 

 The bison or buffalo of our Western plains is doomed to 

 speedy extinction, unless saved by domestication. In fact, 

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