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 eliminated in a few 
generations. Haycraft 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 few 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 eliminated 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, like 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, 
