whole groups of women
mutually belong to one another, leaving only small scope for jealousy.
And furthermore we find at a later stage the exceptional form of
polyandry which still more supersedes all sentiments of jealousy and
hence is unknown to animals.

But all the forms of the group marriage known to us are accompanied by
such peculiarly complicated circumstances that they of necessity point
to a preceding simpler form of sexual intercourse and, hence, in the
last instance to a period of unrestricted sexual intercourse
corresponding to a transition from the animal to man. Therefore the
references to animal marriages lead us back to precisely that point,
from which they were intended to remove us forever.

What does the term "unrestricted sexual intercourse" mean? Simply, that
the restrictions in force now were not observed formerly. We have
already seen the barrier of jealousy falling. If anything is certain, it
is that jealousy is developed at a comparatively late stage. The same is
true of incest. Not only brother and sister were originally man and
wife, but also the sexual intercourse between parents and children is
permitted to this day among many nations. Bancroft testifies to the
truth of this among the Kaviats of the Behring Strait, the Kadiaks of
Alaska, the Tinnehs in the interior of British North America; Letourneau
compiled reports of the same fact in regard to the Chippeway Indians,
the Coocoos in Chile, the Caribeans, the Carens in Indo-China, not to
mention the tales of ancient Greeks and Romans about the Parthians,
Persians, Scythians, Huns and so forth. Before incest was invented (and
it is an invention, a really valuable one indeed), sexual intercourse
between parents and children could not be any more repulsive than
between other persons belonging to different generations, which takes
place even in our day among the most narrow-minded nations without
causing any horror. Even old "maids" of more than sixty years sometimes,
if they are rich enough, marry young men of about thirty. Eliminating
from the primeval forms of the family known to us those conceptions of
incest--conceptions totally different from ours and often enough in
direct contradiction with them--we arrive at a form of sexual
intercourse that can only be designated as unrestricted. Unrestricted in
the sense that the barriers drawn later on by custom did not yet exist.
This in no way necessarily implies for practical purposes an injudi