528 THE THEORY OF EVOLUTION 



" practical " man who is ignorant of these principles. Illustra- 

 tions of what can be accomplished by the application of scientific 

 principles to the practical problems of breeding are seen in the pro- 

 duction of desired varieties of wheat and corn, and of better cattle. 

 Attempts to produce new breeds thus merge with the effort to 

 determine how evolution occurs under the conditions of rigorous 

 scientific experimentation that are described in the chapter on 

 Genetics. 



In conclusion and summary of this evidence for organic evolution, 

 it may be said again that biologists accept evolution as the his- 

 toric course of events in the development of animal life because of 

 evidence from many fields of investigation. Animals resemble 

 each other structurally in varying degrees that seem to indicate 

 the degrees of evolutionary relationship. The structure of animals 

 and their mode of development are as we might expect them to be 

 if evolution has occurred. Likewise, the fossil record of animals 

 and their present geographical distribution can be most reasonablj^ 

 interpreted according to the evolutionary theory. Thus far, the 

 evidence is circumstantial, but it is so extensive as to be convincing. 

 In addition, there is the evidence that evolution has occurred 

 among domesticated animals and is still occurring under the direc- 

 tion of skilled breeders and scientific investigators, although its 

 causes have not yet been fully ascertained. The whole body of 

 evidence is, therefore, overwhelming. For this reason it is hardly 

 possible to find a competent biologist of the present generation 

 who is not convinced of the fact of evolution, no matter how 

 uncertain he may be of its course and causes. 



Human Evolution 



Man's Place in Nature. — With the evolution of all other living 

 beings thus attested, it is impossible to exclude man from this 

 universal process of organic nature. Human Anatomy and Embry- 

 ology; the classification of mankind in the Family Hominidce, 

 closely allied to the Family Simiidce which includes the tailless 

 apes; the fossil record ; and the existing races of mankind all point 

 to evolution as the one reasonable explanation of the facts. Paleon- 

 tology shows that the Order Primates, which includes man, the 

 apes, and monkeys, arose from the general mammalian stock 

 (Fig. 285). In more recent geologic times, fossil remains of 



