96 BIOLOGY AND HUMAN LIFE 



75. The soil and population. The crowding of a population 

 may mean not merely that people live too close together for com- 

 fort or for health ; it may mean also a shortage of food supply 

 due to insufficient soil for growing crops. As the population of 

 a nation grows, the second kind of crowding is likely to become 

 serious. There was a time when thoughtful people looked for- 

 ward to such overcrowding with a feeling that it must result in 

 great destruction of human life or in great suffering through 

 general poverty. Indeed, in times past much of the poverty and 

 famine, and even of warfare, was due to man's inability to get 

 from the soil adequate supplies of food. At the present time, 

 however, we are rapidly learning to increase the yield of our 

 cultivated land out of proportion to the increase in population, 

 chiefly through the application of biological knowledge. 



So far as the soil is concerned, we need not fear that the 

 " Great Mother " will become uninhabitable for many centuries. 

 The pressure of the population, even if it becomes several times 

 as great as it has been in China or India, can be met by the ap- 

 plication of science and cooperative effort to the resources now 

 in sight. If there is to be starvation, it will not be because the 

 earth and the sun and the green plants fail us. It will be be- 

 cause of our own failure to make use of our knowledge in har- 

 mony and cooperation with our fellows. 



MOTHER EARTH 



1. Source of all living matter 



Earth; water; air 



2. Elements taken from the soil by plants 



3. Elements found in plants Elements found in the human body 



