INTRODUCTION 5 



has been ignored, perhaps not even suspected. Yet the 

 results of selective breeding on domestic plants and 

 animals have been well known for a century or more. 

 The marvellous success which has attended the efforts 

 of breeders in obtaining strains of horses, cattle, and 

 other animals fitted for special uses is only equalled by 

 the results of the work of horticulturists in raising 

 new varieties of fruit and flowers. 



Before man's place in nature was understood and 

 acknowledged, the idea that similar though unconscious 

 selection was at work on himself seems but dimly to 

 have crossed his mind. When Lyell and Darwin had 

 placed man in his proper position in the sequence of 

 biological forms, it was seen that principles found to 

 hold generally in the animal and vegetable kingdoms 

 were likely to be worth looking for in the case of the 

 human race. The struggle for life, incessantly at work 

 in the lower world, affects man also. It will tend to 

 modify the character of a nation as it modifies the flora 

 and fauna of a country. Then, as artificial means will 

 change a homogeneous breed of wild animals into the 

 several specialized forms of our domestic flocks and 

 herds, so we must look for a modification of our folk 

 for good or evil by the artificial conditions of modern 

 civilization. There is no finality ; a nation must either 

 be losing or gaining ground, either improving or 

 degenerating. Hence the scientific study of the effect 

 of the existing conditions of any time on the rates of 

 reproduction of different stocks of the nation should be 

 the chief work of the sociologist, and the control of 

 those conditions the supreme duty of the statesman. 



At present the study of environment holds the field. 



