Unilineal kinship makes a direct and simple assignment of social statuses,
rights, and duties by confining transmission to a single descent line.
By contrast, nonunilineal, or cognatic, systems allow for
the construction of social groups and categories through any or all of
an individual's acknowledged relatives beginning with both his/her father
and mother. The open nature of cognatic organization leads to greater complexities
and wider variations than are normally apparent in partilineal or matrilineal
forms.
Cognatic kinship structures can be classified into two basic systems:
bilateral and ambilineal.
Bilateral
systems involve the
inclusion of all of an individual's relatives within a given range.
They are usually ego focused and are 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.
Bilateral Kinship Network (Kindred)
Ambilineal
systems involve an
exclusive
selection of membership in a father's or mother's group, usually upon adulthood.
(Alternative forms are based on a choice of living with one's husband's or
wife's
family after marriage.) 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.
Ambilineal Kinship Group (Ramage)
Relatives included in Ego's ambilineal group are shaded in red.
Purple indicates descendants who have not been assigned membership.
