Man m the Light of Evolution 



ants. This seems to be the rule. But they were 

 probably larger than their invertebrate prede- 

 cessors, and were gaining in size. With the in- 

 crease in size came the increase in length of life. 

 How early this became marked we have no 

 means of knowing. But mammals generally live 

 for several or many years. The hairy or fur- 

 clad mammal can endure quite marked changes 

 of temperature. He was pelted and buffeted 

 with impressions from the outer world. He met 

 new, oft-recurring, and often trying experiences. 

 The lesson was repeated day by day, week after 

 week, and year after year. Nature taught and 

 educated him by hard experience, and by experi- 

 ence he became keen and alert. Instinct might 

 suffice for the short-lived insect, but the mammal 

 was to be intelligent. 



The process of education lasted long, and 

 progress was probably slow and often discour- 

 aging. Professor Osborn tells us that a whole 

 fauna of mammals in early tertiary times became 

 extinct, apparently because their bodies outgrew 

 their brains. Food was abundant and dangers 

 were few for these great beasts. In this primi- 

 tive Eden of ease and peace, prosperity bred 

 idiocy. But such easy fortune was not the lot 



34 



