Although, until a comparatively recent time, the writers who have dealt with the subject of primitive society have been of the opinion that the tribe constituted the earliest organization of society, and that the gens and the family followed, later investigations show conclusively that the gens, next to the remote and obscure division into classes, represents the oldest and most widely spread form of organized society, and that it was through segmentation or division of this archaic group that the tribe was formed. The natural way in which a tribe is formed is from a family or group, which in time increases and divides into many households, still recognizing one another as kindred, and this kinship is so thoroughly felt to be the tie of the whole tribe, that even when there has been a mixture of tribes, a common ancestor is often invented to make an imaginary bond of union.[82] [82] Tylor, _Anthropology_, p. 405. The gens, until a comparatively recent time in the history of the human race, was composed of a female ancestor, all her children and all the children of her daughters, but not of her sons. The sons’ children and their descendants belonged to the gens of their respective mothers. The family, as it appears at the present time, was unknown. The gens was founded on thoroughly democratic principles, each individual composing the group, both female and male, having a voice in the regulation and management of all matters pertaining to the general government of the community. Any injury done to a gentilis was a wrong committed against the entire gens of which she or he was a member, hence to her or his kinsmen each individual looked for protection and for redress of personal wrongs. The fundamental doctrine of tribal life is unity of blood. Although the early groups, under the system of female descent, were united by the actual bond of kinship as traced through mothers, later, when descent came to be traced through fathers, kinship was to a considerable extent feigned. Kinship, under the system of male descent, meant not that the blood of the great father actually flowed in the veins of all the members of the group, but that under a pretence of unity of blood, they were bound together by common duties and responsibilities from which no one of them could escape. By the terms of the compact, every member must stand by her or his own clan. In fact, in all their movements, they must act as one individual; their interests were identical and the quarrel of any member of the group became the quarrel of all counted within the bond of kinship. If homicide were committed, they judged and punished the culprit, but if one of their number was slain by an outsider, the law of blood-feud, which demanded blood in return, was immediately put into execution. Of the gens Mr. Morgan says: