CONSANGUINEOUS MARRIAGES 265 
mediate product for the most highly endowed stock. It is the 
very best inheritance that should be conserved at all costs. Out 
of it come the rare minds that rise like mountain peaks above the 
general level of humanity. And it is to these minds, small in 
number, but incalculably great in influence, that advancement in 
civilization and culture is largely due. 
I cannot close this chapter without a few remarks on the 
increasing fusion of racial elements and the possible eventual 
outcome of this process. As the human species became dispersed 
into various quarters of the globe it became more and more 
divided into isolated groups. Given a heterozygous stock, isola- 
tion would of itself afford a condition under which the race would 
be broken up into varieties through the influence of segregate 
breeding. Asa result of spreading into regions of different climatic 
and other environmental conditions, the race would also tend 
to become modified in different ways through the action of 
natural selection. In the early periods of the history of man when 
he was spreading over and becoming adapted to the diverse 
regions of the earth, the predominant trend of development was 
toward divergence. The result is a multiplicity of groups within 
groups, which ethnologists are still far from having arranged in a 
satisfactory system of classification. 
For long periods and with increasing frequency as mankind 
has advanced, there have been migrations, conflicts and inter- 
mixtures of previously differentiated peoples. But at the present 
time, when railroads and steamships, to say nothing of other 
conveniences of travel and communication, are bringing races into 
closer and closer contact, the process of race fusion goes on at an 
accelerated pace. Many of the old barriers of religion and na- 
tional or sectional prejudice are breaking down. People of minor 
racial distinctions such as those of the countries of Europe are 
rapidly commingling their blood and over large areas such as 
South America, parts of Africa and Asia and in numerous islands 
of the Pacific there is an extensive blending of distinct races. If 
in the early history of mankind development was along diverging 
lines it is now proceeding more conspicuously and rapidly in the 
