Cognatic Descent Systems Cognatic Descent Systems Unilineal kinship makes a direct and simple assignment of social statuses, rights, and duties by confining transmission to a single descent line. The open nature of cognatic organization leads to greater complexities and wider variations than are normally apparent in partilineal or matrilineal forms.
Bilateral systems involve the inclusion of all of an individual's relatives within a given range.
They are usually ego focused and formed by tracing relationships from both parents throughout an everwidening network of kinship called a kindred . A less common variant form, a stock , or bilateral descent group is based on tracing descent lines back to founding ancestors. They are ancestor focused and become organized by tracing descent from either father or mother, but not both, and back through a similarly restricted string of forbearers. Relatives included in Ego's ambilineal group are shaded in red. Purple indicates descendants who have not been assigned membership.