EVOLUTION OF THE HUMAN SPECIES 177 



sufficiently marked to strike the attention of any one 

 who looks about at his fellow-passengers in a crowded 

 street car. But few indeed have a comprehensive 

 knowledge of the wider range of racial variation in 

 which these familiar examples find their place. Anthro- 

 pology, or the science of mankind, is a large and well- 

 organized department of knowledge, dealing with the 

 entire array of structural and physiological characters 

 of all men. One of its subdivisions, anthropometry, is 

 almost an independent discipline with methods of its 

 own ; it describes the characteristics of human races as 

 these are determined by statistical methods of a some- 

 what technical nature. There is still another science, 

 ethnology, which deals more particularly with institu- 

 tions, customs, beliefs, and languages rather than with 

 physical matters, although it is clear that ethnology 

 and anthropology cannot be sharply separated, and that 

 each must employ the results of the other for its own 

 particular purposes. 



Because men have always been interested in the study 

 of themselves, the subject of racial evolution is literally 

 enormous, and the attempt to give anything like a 

 complete description of what is known would obviously 

 be futile. But it is possible to obtain a clear conception 

 of certain of the fundamental principles that fall into 

 line with the other parts of the doctrine of organic evo- 

 lution with which we have now become acquainted. 

 The main questions, therefore, may be stated in simple 

 terms. The first deals with the evidences as to the 

 reality of evolution during the historical and prehistoric 

 development of the various types of man from earlier 

 common ancestors ; the second asks whether the lines 



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