582 BIOLOGY AND HUMAN LIFE 



greatest heroes did not die of malaria is that most of them were never 

 exposed to malarial infection. On the other hand, there are millions of 

 people who are immune to one disease or another and who either never 

 amount to anything, so far as the progress of the race is concerned, or 

 who turn out to be very undesirable citizens. 



Other dangers developed by civilization and man's attempt 

 to conquer the earth are found in war, poverty, and luxury. The 

 human race is the only species of living thing that is constantly 

 setting one part against another. Now, if fighting were a means 

 of selecting the more desirable individuals for the future of the 

 race (the way track trials select the fastest horses for breeding), 

 we might say that war improves humanity. But the fact is that 

 war works just the other way. It is true that the more success- 

 ful tribe or nation may replace the conquered. But in modern 

 times what happens is this: the bravest and the ones most 

 ready to sacrifice themselves for the group, and those who are 

 physically the fittest are the ones who go to war, and are killed 

 in great numbers ; while the feeble, the timid, the ones who do 

 not care, remain behind and become the parents of the next 

 generation. Instead of selecting toward improvement of the 

 race, war always selects toward a deterioration. 



Our conquest of the environment has made possible very great 

 increase in our productivity; but this has gone hand in hand 

 with increasing differences in wealth. The concentration of 

 poverty has meant the demoralization and degradation of mil- 

 lions of people in our country ; and, on the other hand, the em- 

 phasis upon luxury and idleness and extravagance has been just 

 as demoralizing and weakening to a few of the extremely 

 wealthy. These results are also in the direction of breeding 

 poorer qualities in human beings. 



416. The social heritage. As organisms the human beings of 

 today are probably very much like those that lived thousands 

 of years ago. There is reason to believe that the brains and 

 abilities of the people who made ancient civilizations in differ- 

 ent parts of the world were about the same as our own. Man 

 has learned to preserve the results of experience in customs 



