arried. The unmarried have not only
all the incentives of the married to keep down their birth-rate but also
the obvious and powerful incentive of concealment as well.

Passing to the relative death-rate of the illegitimate and legitimate
progeny, the actual data invariably indicate a decided advantage of the
legitimately born. The reasons are too obvious to be retailed.

Now, then, knowing that the racial contribution of the sexually moral is
greater than that of the sexually immoral, we may compare the quality of
the sexually moral and immoral, to get the evolutionary effect.

For this purpose a distinction must be made between the individual who
has been chaste till the normal time of marriage and whose sexual life
is truly monogamous, and that abnormal group who remain chaste and
celibate to an advanced age. These last are not moral in the last
analysis, if they have valuable and needed traits and are fertile,
because in the long run their failure to reproduce affects adversely the
welfare of their group. While the race suffers through the failure of
many of these individuals to contribute progeny, probably this does not
happen, so far as males are concerned, as much as might be supposed, for
such individuals are often innately defective in their instincts or, in
the case of disappointed lovers, have a badly proportioned emotional
equipment, since it leads them into a position so obviously opposed to
race interests.

But, to pass to the essential comparison, that between the sexually
immoral and the sexually moral as limited above, it is necessary first
of all to decide whether monogamy is a desirable and presumably
permanent feature of human society.

We conclude that it is:

1. Because it is spreading at the expense of polygamy even where not
favored by legal interference. The change is most evident in China.

2. In monogamy, sexual selection puts a premium on valuable traits of
character, rather than on mere personal beauty or ability to acquire
wealth; and

3. The greatest amount of happiness is produced by a monogamous system,
since in a polygamous society so many men must remain unmarried and so
many women are dissatisfied with having to share their mates with
others.

Assuming this, then adaptation to the condition of monogamous society
represents race progress. Such a race profits if those who do not comply
with its conditions make a deficient racial contribution. It follows
then that sexual immor