SCIENCE AND SOCIAL PROGRESS 249 



this disease; or when the havoc caused by insect pests has become so 

 disastrous as to cause a careful study of such forms of life in order to 

 eradicate them. These influences, so clearly at work now, have, how- 

 ever, been in operation in greater or less degree since the sixteenth cen- 

 tury. They were at work also during the later period of Greek civiliza- 

 tion and had it not been for the persistence of religious superstition 

 they would have been effective in the Arabian civilization. 



Turning now to the effects of the biological sciences, three important 

 influences may be mentioned : First, biological knowledge, through the 

 prevention and cure of disease, has greatly decreased the rates of mor- 

 tality ; secondly, through the destruction of injurious pests and through 

 the selection and cultivation of vegetable and animal life, it has multi- 

 plied and improved the food supply, and incidentally it has increased 

 other forms of wealth. In these two ways then the sciences of life have 

 made possible an increase in population at least as great as that made 

 possible by the physical sciences. But it should be noted that the bio- 

 logical sciences are supplementary to the physical sciences. Both stim- 

 ulate the growth of population, but the biological sciences do so with- 

 out the suffering and waste prevalent before their development. 

 Neither group can do its proper work without the other and each group 

 has been a stimulus to the growth of the other. Sanitary measures 

 could not be carried out without engineering knowledge, the present 

 concentration of population would be impossible without sanitary pre- 

 cautions, and a large food supply would be useless without rapid means 

 of transportation and communication. Finally, biological sciences have 

 to some extent, and will to a greater degree, improve individuals and 

 the race through selection and education. Medical science has been 

 severely criticized because it has counteracted the effects of natural 

 selection by making it possible for the unfit to live and propagate their 

 kind. Without doubt a partial knowledge of the laws of life has pro- 

 duced some temporary evil effects along with the good. But the remedy 

 lies not in a return to former conditions, but in the adoption of new 

 methods through the perfection of our knowledge. Psychology has 

 already enabled us to make rapid strides in our system of education and 

 in our treatment of mental diseases ; and a better knowledge of the laws 

 of heredity and improved methods of social control will enable us con- 

 sciously to improve the human species in ways most advantageous. And 

 they will accomplish this more quickly and effectively than by the 

 blind process of natural selection. 



The past century may be regarded as preeminently a period of bio- 

 logical discovery, not because the physical sciences have not advanced 

 also in a marked degree, but because biological discovery is the new 

 factor which has been added to science to influence social progress. 

 This new factor is destined to further in a wonderful degree individual 



