ion, and among whom possibly the rise of humanitarian
ideas not only tends to counteract the weeding out of the unfit, but
even makes it relatively easy for them to propagate their species. What
the result of the intermarriage of cousins is when war, famine, and
infanticide are efficient weeders out of the unfit, we cannot say.
Possibly or even probably the ill results would be inappreciable. It
must not be forgotten that the marriage of near relatives is only
harmful because or if it hands on to the children of the union an
hereditary taint in a strengthened form, a result which is likely to
follow in civilised life because hereditary taints are allowed to
flourish unchecked by prudence and controlled by natural selection only
so far as humanitarianism will permit it. These hereditary degeneracies
however are probably largely if not entirely absent among savages. It is
therefore open to question how far intermarriage of cousins would prove
harmful under such conditions.

Statistics of the influence of cousin-marriage are not however what Mr
Morgan wants. It is essential for him to prove that father-daughter
marriage is more harmful than brother-sister unions.

It might be imagined that the data for estimating the effect of the
union of father and daughter would be non-existent, but this is not so.
Within the last few years it has been stated that such unions are common
in parts of South America, and that the children, so far from being
degenerates, are remarkably healthy and vigorous[149]. This is of
interest in connection with Mr Atkinson's speculations as to the history
of the family. In this connection it may be pointed out that such
unions, _ex hypothesi_, are unlikely to result in continual in-and-in
breeding, and would in all probability seldom be continued beyond the
first alliance of this nature.

We are practically in complete darkness as to the results of brother and
sister marriage in the human species. We have of course various cases of
ruling families who perpetuated themselves in this way, but the data
from such peoples refer to an advanced stage of culture and to a
favoured class. They are not therefore applicable to similar unions
among savages where they formed, as Mr Morgan suggests, the invariable
practice. It is however possible to deduce from very simple
considerations the probabilities as to the respective effects of
adelphic and father-daughter unions. In the first place, as has been
already p