ountains and trees, and
the most important animals of his environment, whether they destroyed
or assisted to preserve his life. The ideas of propitiation, atonement
and purification were then imparted to the sacrifice, and it became an
offering to a god. [157] But the primary idea of eating or drinking
together as a bond of union was preserved, and can be recognised in
religious and social custom to an advanced period of civilisation.

67. The origin of exogamy.

Again, Dr. Westermarck shows that the practice of exogamy or
the avoidance of intermarriage did not at first arise between
persons recognised as blood relations, but between those who lived
together. "Facts show that the extent to which relatives are not
allowed to intermarry is nearly connected with their close living
together. Generally speaking the prohibited degrees are extended
much further among savage and barbarous peoples than in civilised
societies. As a rule the former, if they have not remained in the
most primitive social condition of man, live not in separate families
but in large households or communities, all the members of which
dwell in very close contact with each other." [158] And later, after
adducing the evil results of self-fertilisation in plants and close
interbreeding in animals, Dr. Westermarck continues: "Taking all these
facts into consideration, I cannot but believe that consanguineous
marriages, in some way or other, are more or less detrimental to the
species. And here I think we may find a quite sufficient explanation
of the horror of incest; not because man at an early stage recognised
the injurious influence of close intermarriage, but because the law of
natural selection must inevitably have operated. Among the ancestors
of man, as among other animals, there was no doubt a time when blood
relationship was no bar to sexual intercourse. But variations here,
as elsewhere, would naturally present themselves; and those of our
ancestors who avoided in-and-in breeding would survive, while the
others would gradually decay and ultimately perish. Thus an instinct
would be developed, which would be powerful enough as a rule to
prevent injurious unions. Of course it would display itself simply as
an aversion on the part of individuals to union with others with whom
they lived; but these as a matter of fact would be blood relations,
so that the result would be the survival of the fittest."

68. Promiscuity and female descent