In the ancient gens descent was limited to the female line. It embraced all such persons as traced their descent from a supposed common female ancestor, through females, the evidence of the fact being the possession of a common gentile name. It would include this ancestor and her children, the children of her daughters, and the children of her female descendants, through females, in perpetuity, while the children of her sons and the children of her male descendants, through males, would belong to other gentes, namely, those of their respective mothers. Such was the gens in its archaic form, when the paternity of children was not certainly ascertainable, and when their maternity afforded the only certain criterion of descents.
This state of descents which can be traced back to the Middle Status of savagery, as among the Australians, remained among the American aborigines through the Upper Status of savagery, and into and through the Lower Status of barbarism, with occasional exceptions. In the Middle Status of barbarism the Indian tribes began to change descent from the female line to the male, as the syndyasmian family of the period began to assume monogamian characteristics. In the Upper Status of barbarism descent had become changed to the male line among the Grecian tribes, with the exception of the Lycians, and among the Italian tribes, with the exception of the Etruscans. Between the two extremes, represented by the two rules of descent, three entire ethnical periods intervene, covering many thousands of years.
As intermarriage in the gens was prohibited, it withdrew its members from the evils of consanguine marriages, and thus tended to increase the vigor of the stock. The gens came into being upon three principal conceptions, namely, the bond of kin, a pure lineage through descent in the female line, and non-intermarriage in the gens. When the idea of a gens was developed, it would naturally have taken the form of gentes in pairs, because the children of the males were excluded, and because it was equally necessary to organize both classes of descendants. With two gentes started into being simultaneously the whole result would have been attained, since the males and females of one gens would marry the females and males of the other, and the children, following the gentes of their respective mothers, would be
