Variations either advantageous or disadvantageous for the race or individual may either of them become more prevalent by close intermarriage.

It seems, however, to have been shown by the customs of the human race that very close intermarriage is disadvantageous.
Eugenics, which signifies an attempt at the betterment of the race by the avoidance of bad heredity, has within recent years attracted much attention and is of importance.

Some of its advocates have become so enthusiastic as to believe that it will be possible to breed men as cattle and ultimately to produce a race ideally perfect.

It is true that by careful selection and regulation of marriage certain variations, whether relating to coarse bodily form or to the less obvious changes denoted by function, can be perpetuated and strengthened.

That the Semitic race excels in commerce is probably due to the fact that the variation of the brain which affected favorably the mental action conducive to this form of activity, was favorable for the race in the hostile environment in which it was usually placed and transmitted and strengthened by close intermarriage.