d marriage between Jews and Aryans are generally
less fecund; but this fact is not yet sufficiently explained.
Mulattoes, or hybrids between negroes and whites, constitute a
degenerate race and hardly viable, at any rate if their descendants do
not return entirely to one of the original races. Half-breeds between
whites and American Indians, also called Ladinos, seem on the contrary
to form a viable race, but one of little valor.

PROHIBITION OF CONSANGUINEOUS MARRIAGES

Sexual union between near relations nearly always causes a feeling of
repugnance in man, and has been stigmatized by the term _incest_.
Coitus between mother and son especially excites disgust. Sexual
connection between parents and children, as well as between brothers
and sisters is, however, common among certain tribes. Many other races
allow marriage between brothers and sisters, but this is elsewhere
generally condemned.

Among the Weddas, marriage between an elder brother and his younger
sister is considered normal, while that between a younger brother and
his elder sister, or between a nephew and his aunt, is regarded as
unnatural. The latter simply shows that unions between young men and
old women are not natural. Unions between brothers and sisters, and
especially between half-brothers and half-sisters were licit among the
Persians, Egyptians, Syrians, Athenians and ancient Jews. Those
between uncles and nieces (more rarely between aunts and nephews) are
sometimes permitted, sometimes prohibited. With the exception of Spain
and Russia marriages between first cousins are allowed in Europe.

=Exogamy and Endogamy.=--Among many savages the prohibition of
consanguineous marriage may be extended to relationship of the third
degree. Marriage may even be prohibited among all members of the same
tribe or clan, even when they are not related. This is called
_exogamous_ marriage, and reaches its extreme development among the
Australians, who are only allowed to marry into remote clans.

We thus see that the great majority of savages extend their idea of
incest much further than we do. The reason of this has been much
discussed. It was formerly said that consanguineous marriage was
contrary to the commandments of God; that it offended the natural
sentiment of modesty; that it obscures relationship, etc. Nowadays, it
is said to be injurious to posterity. Ethnography teaches us, however,
that these statements are of little value.

Along with the exo