Throughout all the earlier stages of culture, and even into the civilized period, we find society organized with the clan for its ultimate unit, although in course of time its character becomes greatly altered by the substitution of kinship in the paternal, for that in the maternal line. By long-continued growth and repeated segmentation the primitive clan was developed into a more complex structure, in which a group of clans constituted a _phratry_ or brotherhood, and a group of phratries constituted a _tribe_. This threefold grouping is found so commonly in all parts of the world as to afford good ground for the belief that it has been universal. It was long ago familiar to historians in the case of Greece and Rome, and of our Teutonic forefathers,[67] but it also existed generally in ancient America, and many obscure points connected with the history of the Greek and Roman groups have been elucidated through the study of Iroquois and Algonquin institutions. Along with the likenesses, however, there are numerous unlikenesses, due to the change of kinship, among the European groups, from the female line to the male. [Footnote 67: The Teutonic _hundred_ and Roman _curia_ answered to the Greek _phratry_.] [Sidenote: Effect of pastoral life upon property and upon the family.] This change, as it occurred among Aryan and Semitic peoples, marked one of the most momentous revolutions in the history of mankind. It probably occurred early in the upper period of barbarism, or late in the middle period, after the long-continued domestication of animals had resulted in the acquisition of private property (_pecus, peculium, pecunia_) in large amounts by individuals. In primitive society there was very little personal property except in weapons, clothing (such as it was), and trinkets. Real estate was unknown. Land was simply _occupied_ by the tribe. There was general communism and social equality. In the Old World the earliest instance of extensive "adverse possession" on the part of individuals, as against other individuals in the clan-community, was the possession of flocks and herds. Distinctions in wealth and rank were thus inaugurated; slavery began to be profitable and personal retainers and adherents useful in new ways. As in earlier stages the community in marital relations had been part of the general community in possessions, so now the exclusive possession of a wife or wives was part of the system of private property that was coming into vogue. The man of many cattle, the man who could attach subordinates to him through motives of self-interest as well as personal deference, the man who could defend his property against robbers, could also have his separate household and maintain its sanctity. In this way, it is believed, indissoluble marriage, in its two forms of monogamy and polygamy, originated. That it had already existed sporadically is not denied, but