The pairing family arose on the boundary line between savagery and barbarism, generally in the higher stage of savagery, here and there in the lower stage of barbarism. It is the form of the family characteristic for barbarism, as group marriage is for savagery and monogamy for civilization. In order to develop it into established monogamy, other causes than those active hitherto were required. In the pairing family the group was already reduced to its last unit, its biatomic molecule: one man and one woman. Natural selection, had accomplished its purpose by a continually increasing restriction of sexual intercourse. Nothing remained to be done in this direction. Unless new social forces became active, there was no reason why a new form of the family should develop out of the pairing family. But these forces did become active.
We now leave America, the classic soil of the pairing family. No sign permits the conclusion that a higher form of the family was developed here, that any established form of monogamy ever existed anywhere in the New World before the discovery and conquest. Not so in the Old World.
In the latter, the domestication of animals and the breeding of flocks had developed a hitherto unknown source of wealth and created entirely new social conditions. Up to the lower stage of barbarism, fixed wealth was almost exclusively represented by houses, clothing, rough ornaments and the tools for obtaining and preparing food: boats, weapons and household articles of the simplest kind. Nourishment had to be secured afresh day by day. But now, with their herds of horses, camels, donkeys, cattle, sheep, goats and hogs, the advancing nomadic nations—the Aryans in the Indian Punjab, in the region of the Ganges and the steppes of the Oxus and Jaxartes, then still more rich in water-veins than now; the Semites on the Euphrates and Tigris—had acquired possessions demanding only the most crude attention and care in order to propagate themselves in ever increasing numbers and yield the most abundant store of milk and meat. All former means of obtaining food were now forced to the background. Hunting, once a necessity, now became a sport.