l examination of the facts is convincing that they did do so.
In like manner, they were led to try to avert overpopulation by
folkways. They acted "instinctively," or automatically, not rationally.
Inbreeding preserves a type but weakens the stock. Outbreeding
strengthens the stock but loses the type. In our own mores each one is
forbidden to marry within a certain circle or outside of another circle.
The first is the consanguine group of first cousins and nearer. The
latter is the race to which we belong. Royal and noble castes are more
strictly limited within the caste. Amongst savage peoples there were two
ideas which were in conflict: (1) all the women of a group were regarded
as belonging to all the men of that group; (2) a wife conquered abroad
was a possession and a trophy. Endogamy and exogamy are forms of the
mores in which one of these policies has been adopted to the exclusion
of the other. Of that we have an example in civilized society, where
royal persons, in order to find fitting mates, marry cousins, or uncles,
or nieces, and bring on the family the evils of close inbreeding
(Spain); or they take slave women as wives and breed out the blood of
their race (Athenians, Arabs). The due adjustment of inbreeding and
outbreeding is always a difficult problem of policy for breeders of
animals. It is the same for men. The social interests favor inbreeding,
by which property is united or saved from dispersion, and close
relationship seems to assure acquaintance. At Venice, in the time of
glory and luxury, great dowers seemed to threaten to dissipate great
family fortunes. It became the custom to contract marriages only between
families which could give as much as they got. "This was not the least
of the causes of the moral and physical decline of the Venetian
aristocracy."[1145]

+366. Polygamy and polyandry.+ Polygamy and polyandry are two cases of
family organization which are expedient under certain life conditions,
and which came into existence or became obsolete according to changes
in the life conditions, although there are also cases of survival, due
to persistence of the mores, after the life conditions have so changed
that the custom has become harmful. Population, so far as we know,
normally contains equal numbers of the two sexes, except that there are
periods in which, for some unknown reason, births of one sex greatly
preponderate over those of the other.[1146] There are also groups in
which the food