CHAPTER XI 

 THE EVOLUTION OF MAN 



The differences between man and the lower animals are such 

 that we can hardly avoid being prejudiced judges of our place in 

 the world. We know relatively little cither of the world or of our- 

 selves and there are many factors in our lives as human beings 

 which tend to influence our evaluation of such things as we do 

 know. Science tries to set aside these prejudices and to judge the 

 characteristics of man as impartially as those of other organisms. 

 It has succeeded to some degree and therefore gives us a more 

 logical account of ourselves than any other field of knowledge, 

 but in this as in other fields we must be constantly aware that our 

 information is incomplete. 



Man's Systematic Position. Of man's position among other 

 organisms, fortunately, we need not be in doubt. Although he 

 stands well al)ove the other animals in some ways, he is animal in 

 structure and in functions and shows in his anatomy as definite 

 relationships as are displayed by the forms already studied. Among 

 his animal structures he has the dorsal tubular nervous system, 

 the vertebral column which replaces the embryonic notochord, 

 and at one stage evidence of the pharyngeal clefts which stamp 

 him a chordate and a vertebrate. Within this phylum he has the 

 hair, the circulatory system, and the mode of reproduction of the 

 mammals, and in the highly specialized connection of parent 

 and embryo he shows the most conspicuous character of the Eu- 

 theria. 



The Eutheria include four groups, the Unguiculata or clawed 

 animals, the Primates or animals with nails, the Ungulata or 

 hoofed animals, and finally the Cetacea, made up of such highly 

 specialized marine creatures as the whales, dolphins and por- 

 poises. Obviously man is most nearly like those species which 

 have nails on the digits, and so we find him a member of the order 

 Primates, in the group of the same name. 



The Primates. Characteristics. In general the primates are 

 arboreal animals. They have prehensile appendages with the 



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