MAMMALIAN DENTITION 



CHAPTER I 



ENVIRONMENT AND THE EVOLUTION OF 

 VERTEBRATES 



The relation of Man to other Mammals — Geological changes 

 since the first appearance of land vertebrates — Influence 

 of the division of land masses upon animal evolution — 

 Preservation of bones and teeth — Relation of climate to 

 evolution and migration — Definition of evolutionary 

 terms — Variations and mutations. 



That which fires the imagination, which encourages us to 

 follow all the devious paths of mammalian tooth development 

 in the study we are undertaking, is the evolution of ourselves. 

 Our chief interest naturally centers around our own dentition. 

 When we come to ask ourselves what characters of really fun- 

 damental importance differentiate us from other animals we 

 find these are singularly few. The perfection of the erect pos- 

 ture, the power of speech and the great increase in the parietal 

 association area of the brain separate us perhaps most clearly 

 from even our nearest animal relatives. Other features such as 

 size and certain characters of the teeth are by no means con- 

 fined to our own particular history ; they are shared in com- 

 mon Avith other animals. We cannot isolate ourselves from 

 our nearest mammalian kin with which we are classed in the 

 order Primates. 



If in the attempt to trace our own history we follow back 

 the ancestors of the Primates to their earliest beginning we 



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