4 INTRODUCTION: THE FIELD AND PROBLEMS OF BIOLOGY 



only rational explanation of many human attributes that are inexplicable 

 on any other grounds. 



The organism as a unit in a socioeconomic complex. Our fourth view- 

 point is concerned with another sort of relationship among organisms. No 

 animal or plant "liveth unto itself." Instead it is a member of a complex 

 society of often diverse kinds of organisms brought together by more or 

 less similar responses to particular intensities of heat, light, moisture, 

 etc. These organisms exhibit various kinds of interdependencies in the 

 competition for the necessities of existence. Much of this interdependence 

 is based upon the fact that the whole organic world is a huge "energy 

 cycle." Energy from the sun, captured by the photosynthesis of green 

 plants, provides the driving power upon which all forms of life are directly 

 or indirectly dependent. The competition for this energy and its transfer 

 from organism to organism involve a host of reciprocal actions — finding 

 food, competition for food, avoiding being eaten, and cooperation for 

 mutual aid, as well as many less direct relationships. 



Regarded from this viewpoint, the organism presents a number of new 

 problems. What role does it play in the economy of nature? How does 

 its existence affect the other members of its society? What other organisms 

 affect its own welfare? These are far from simple questions, and to 

 answer them requires a multitude of difficult and subtle observations and 

 many quantitative data. From such observations and such data comes 

 much of man's ability to utilize and conserve the living world for his own 

 needs and purposes. Medicine, agriculture, and forestry are dependent 

 upon our knowledge of such relationships, and hope for the conservation 

 of natural biotic resources — fish, game, and other wildlife — rests upon 

 their adequate understanding. 



These four aspects of the organism — its roles as an individual, as a 

 member of its race, as a product of evolution, and as a unit in a competi- 

 tive and in part cooperative society — form the four chief subdivisions of 

 this book. It must be emphasized that all are related aspects of each and 

 every organism. Each individual and the niche that it occupies in the 

 organic world have been shaped by evolution, and this evolution, in 

 turn, has been the result of the functioning of the individual organism's 

 ancestors — members of successive races that lived and competed with 

 other organisms in the world about them. 



BIOLOGY AS A SCIENCE: THE SCIENTIFIC METHOD AND ITS LIMITATIONS 



It is important to keep in mind that biology, in attempting to answer 

 the various questions confronting it, has adopted the methods and 

 technique of a science. Any science is a body of knowledge concerning 

 some particular "field," or group of phenomena, in the universe in which 



