The above diagram illustrates the formation of ambilineal groups, also
called ramages. |
Ego has chosen to join his father's ramage which brings him into a descent line which includes a set of descendants, shaded in blue, of his father's mother's mother, determined according to a series of personal choices.
Ego's brother has decided to join his mother's group, whose members are shaded in red.
Ego's children and brother's children have not yet made a ramage selection.
Ambilineal descent groups, also termed ramages, are similar to unilineal forms since they involve the formation of discrete and exclusive units. However, they also allow for individuals to chose group membership at at least one point in their lives. Reasons for assuming membership in one group or another usually depend on the availability of corporately owned lands, but will of course also be influenced by political factors and personal friendships among kin.
Membership decisions are further complicated by additional options presented at marriage. People can choose to join a husband's or wife's group rather than one of those traced through their natal families, thus raising four possible alternative ramages: ego's father's, ego's mother's, ego's wife's father's, and ego's wife's mother's. This complication is reduced in many instances by assigning children initially to one of their parents' ramages, leaving a single choice of whether a couple resides with the husband's or wife's group upon marriage.
The structural features of ambilineal descent systems offer the advantages of supporting coherent and permanent groups with fixed assets and territories as well as a flexible arrangement for distributing populations to match land availabilities. Accordingly, ambilineal groups are very often found in island settings, especially in Oceania, where the arable land base is restricted.