NATURAL SELECTION IN MAN 183 



In the most malarious districts of the West coast of Africa mem- 

 bers of the white race would probably be eHminated in a few 

 generations. Hay craft states that "the black population of 

 Sierre Leone have only a mortality of ,24 per cent, from malaria, 

 while the mortality of the white settlers is 47 per cent." Measles, 

 which is a common but not severe malady with us, is said to have 

 swept away 40,000 of the 150,000 of the inhabitants of the Fiji 

 Islands in 1876. Tuberculosis is apparently more fatal among 

 the negroes, American Indians and the races of the South Pacific 

 than it is among ourselves. The Chinese enjoy a peculiar im- 

 munity to typhoid fever, and cancer is probably more prevalent 

 in Caucasians than among more primitive races. 



These are a tew of the facts which indicate that the same selec- 

 tive agency may act very differently upon different racial stocks. 

 The complex of conditions presented by life in India bear more 

 hardly upon Europeans than upon the Hindus. In the United 

 States the conditions, which include economic and social as well 

 as climatic factors, are much more fatal to the negroes than to the 

 whites. According to the last census reports the anticipation of 

 life for white males is 50.23 years and for white females 53.62 

 years; but for negro males it is only 35.05 years and for negro 

 females 37.67 years. 



The effect of selective agencies upon different races doubtless 

 has much to do in determining the present geographical distribu- 

 tion of the races of mankind. The negro population would never 

 invade the arctic circle even if there were no other human com- 

 petitors; and were it not for their relative immunity to malaria 

 they would probably long ago have been eHminated from Africa 

 by invaders from other lands. As Dr. J. A. Lindsay has pointed 

 out, the selective influence of disease cannot be treated in general 

 terms. Some diseases, Uke the plague, cholera and typhus pro- 

 duce much greater ravages among the slum elements of the popu- 

 lation than among the well-to-do, whereas influenza is much more 

 apt to attack all classes alike. The latter disease causes a much 

 higher death rate among the older people and especially those 

 with pulmonary affections. The common children's diseases, 



