THE ROOTS OF TEETH 



263 



close relationship between the root tips and the canal as one 

 would expect from the primitive nature of this jaAv. The rela- 

 tive shortness of the roots in human teeth is the precise opposite 

 of the condition found in the Orang for the extreme length of 

 the tooth roots of which no adequate explanation has yet been 

 offered. If now we examine a skiagram of the jaws of the 

 Aye-aye Ave note once again shortness of the roots especially 



Fig. 96. — Skiagram of jaws of Negro (Skull 524, W.R.U.). The molar roots are 

 relatively long in this case and approximate the inferior dental canal almost as in the 

 Anthropoid. This is not so in all human mandibles. 



in the second and third molars when we compare these with the 

 teeth of other nearly related Lemurs (Fig. 97). We note 

 further that associated with the shortness of roots is the lack 

 of a well-defined neck. In Heidelberg Man there is also a prac- 

 tical absence of the tooth neck. The Aye-aye is a marked ex- 

 ception to the retention in Primates of a relatively primitive 

 type of tooth. It is a significant exception because the features 

 of its cheek teeth assist us to realize what is happening in the 



