PART II 



HUMAN BIOLOGY 



CHAPTER XV 



LIPE PROCESSES OF MAN 



142. Adaptation. — Adaptation includes all the variations 

 in structures and habits which have been formed by an 

 animal or plant to enable it to live in its own particular 

 environment. Thus certain forms are adapted to living in 

 the tropics, others in the temperate regions, and still others 

 in the arctic regions. Living things which can adapt their 

 lives to our northern winters do not need to migrate south 

 as cold weather comes on in the fall. The frog cannot 

 migrate, but hibernates in the mud. 



Man is the best adapted of all animals to live in all parts 

 of the world. When and where man began to live on the 

 earth is not accurately known, but it was many thousands 

 of years ago. He has been able to spread over the face of 

 the earth because he can control his surroundings, that is, 

 if he happens to live where there are many enemies, he in- 

 vents destructive weapons and kills his enemies or drives 

 them away. This is true even of disease, — man's greatest 

 enemy. Again, most animals are either flesh-eating or 

 plant-eating, but man is both, and because he lias learned 

 to eat a greater variety of both kinds of food than any 

 other animal, it is easier for him to live and to raise his 

 children in all climates. 



161 



