COMMUNITY OF DESCENT 43 



logical unit selected for comparison is of no moment. 



All the zoological units with which nations have 

 been compared have this in common, that they are 

 of the same stock and are stamped with the same 

 hereditary material. Blood relationship is rooted in 

 the central idea of evolution. What binds together 

 the members of a species, sub-species, variety or race, 

 is the link of common descent. Individuals are born, 

 struggle, reproduce and die that the species may 

 flourish. Nature is careless of the single life, careful 

 of the type, and it is possible for her to be lavish 

 with individual lives, because the qualities of the 

 type are preserved in all the members of the species. 

 In discussions on evolution and natural selection, 

 the conception of common descent is an implied 

 major premiss. In anatomy and embryology our 

 constant effort is to distinguish between homologies, 

 resemblances due to the possession of a common 

 hereditary material, and homoplasies, resemblances 

 imposed on different hereditary material. In sys- 

 tematic zoology we are not satisfied with a classifica- 

 tion unless it exclude resemblances among creatures 

 that are not akin, and rely wholly on resemblances 

 that are inherited from a common ancestor. On the 

 theory of evolution the tree of life is a genealogical 

 tree. 



Now if we apply this conception of racial commu- 

 nity to the nations of modern Europe, we shall find 

 that it does not hold. 



Apart from a few separate problems, such as the 

 origin of the Jews, the Basques and the Lapps, the 

 best zoological opinion distinguishes three distinct 

 races or racial types amongst the white population 



