Inheritance rules in unilineal systems specify that status and property are passed exclusively through male or female descent lines, usually in the context of corporate group control of collectively owned land and other assets. Bilateral institutions differ from lineal transmission insofar as property can be claimed from either or both parents and is normally subject to individual rather than group ownership. These conditions result in a common trend toward partible inheritance, or the equal division of a person's assets among all their children, which was the standard inheritance practice in early European societies, as it is today. This institution is often tied to the practice of testamentary inheritance, in which a person can will his/her property to selected relatives or even unrelated friends. (Note that wills and testaments can also be present in unilineal societies as in ancient Rome and in the Akan and Igbo examples developedfor this tutorial).
While the principle of partible inheritance is simply stated in theory, structural and practical concerns have created some interesting accommodations in specific cultural traditions as represented in European social history.
The Salic laws of the Frankish State form the earliest European inheritance legislation subsequent to the Roman period. They contain some interesting provisions that reflect the importance and structure of the kindred, the extended kinship circle that counterbalanced the importance of the nuclear family that was to become so salient in later periods. Property was classified into two types: inherited family estates (allods) and self acquired personal assets (acquests). Inherited property was transferred along lines set within the structure of the kindred. Surviving brothers assumed precedence over spouses or children. Sons and daughters inherited subsequently, but if a man or woman died without children or siblings, family property was to pass to the closest kin within their father's or mother's kindred depending upon its origin. Self acquired property was divided between a surviving spouse and children, depending upon their ages. Boys were given precedence over girls, who were not allowed to inherit land but were otherwise awarded access to property through marriage settlements in the form of dowries and endowments. If a person died without a spouse or children, his/her acquests were reallocated in the following order: parents, siblings, father's sibling,mother's sibling, closest extended kin on father's side according to the canon degree calculation. (Murray 1983:117-212, Paul Halsall 1996 The Law of the Salian Franks, Internet Medieval Sourcebook).
The complex divisions of different property types eventually caused problems in the course of European history. Population increases and the ever increasing concentration of assets within the upper nobility and the Church led to highly uneconomic subdivisions of land within the rest of the population. Families resorted to a new practice of primogeniture, formally known as "permanent entail", that introduced a patrilineal element into the family and inheritance forms (Gies and Gies 1987:125). In this system, estates and statuses passed undivided to eldest sons, or sometimes to only daughters, permanently dispossessing junior brothers, who were often left with the only alternatives of joining the clergy, becoming wandering knights, or marrying heiresses. This late medieval institution has been assigned to a specific category, the "stem family", which persisted up unto the time of the Industrial Revolution. Among other implications the disappearance of the older inheritance system weakened the kindred and other extended family instituions, which have not reemerged with the reemphasis partible inheritance in contemporary society.