Ambilineality is a form of kinship affiliation of cognatic descent that relies on self-defined affiliation within a given social system. Meaning individuals have the choice to be affiliated with their mother’s or father’s group. Common features of societies that practice ambilineality are a shared set of land, communal responsibilities, and collective ownership of some segments of wealth and debt in their societies. This system of descent is distinct from more common genealogical structures in that rather than determining affiliation and descent using the standard determinants of biological and genealogical relation, it instead relies heavily on voluntary affiliation with one’s group, oftentimes being determined by factors including residence.
Societies practicing ambilineal descent are especially common in Southeast Asia and the Pacific Islands. Polynesian cultures and Micronesian cultures are often ambilineal, including, for example, Samoans, Māori, Hawaiians and people of the Gilbert Islands. The indigenous peoples of Northwestern North America are also followers of ambilineality; and it is also found among the Southern Yoruba people residing in West Africa.
Ambilineality is a Cognatic descent system in which individuals may be affiliated either to their father’s or mother’s group. This type of descent results in descent groups which are non-unilineal in the sense that descent passes either through women or men, contrary to unilineal descent , whether patrilineal or matrilineal. Affiliation to a descent group will be determined either by choice or by residence. In the latter case, children will belong to the descent group with whom their parents are living.
Generally, an ambilineal descent group consists of known descendants who can trace their line of descent, through either the male or female line, to the individual who was given usage rights over the land.
The grantee’s descendants have absolute usage rights to a portion of land. If they are residents, they are to be appointed to leadership and administration positions relating to the governance of the land. Those living descendants of the chosen ancestor who follow these claims to land comprise an ambilineal descent group with corporate interests in the land granted to the ancestor.
Similarly, inheritance is acquired through mother and father and property is transmitted through both sons and daughters, as all genders have the right to inheritance
In an ambilineal descent system the members can choose and change their affiliation or clan. This means that membership in an ambilineal group is associated with more freedom and is less binding and restricting than in unilineal descent groups. The flexibility of the descent group enables people to exercise a greater choice in their behavior towards kinsmen, especially distant kins. Furthermore, a person can choose whether or not they will honor their group responsibilities.
The ambilineal system also gives way to a more variable group membership and a more flexible group structure. Oftentimes people use the ability of choice to realign themselves with the more powerful or higher status option. For example in the Togan people of the Northern Gilbert Islands it is common for a couple, with differing social status, to join the descent group with the higher status
India:
In the Tiwa (Lalung) people who live at the Assam-Meghalaya border area in India, ambilineal descent is evident through their marriage and residence practices. At marriage each couple has the choice to join the wife or husband’s clan. There are no set rules as to which house a couple occupies after marriage but, among the Tiwa people gobhia (husband joining the wife’s house) is more common than poari (wife joining husband’s house). Any children born to the couple belong to the group chosen at the time of marriage. This means that an individual inherits the mothers name if born into her house or the fathers name if born into his house.
There is a spiritual dimension to ambilineal descent in Tiwa culture. Membership and affiliation to a descent group is expressed via surname (and domestic belonging/ residence associated) as well as connection to deities. The Tiwas believe that there are numerous deities that inhabit the home. At birth a child inherits the house’s descent group and the bonds that have been established between the god inhabiting the home. This affiliation with the deities serves as a principal criteria for lineage identification because the individual is associated with all of the houses within the descent group that are worshipping the same group deity. For example, two individuals who have the same surname could claim unrelatedness if they do not worship the same group deity.
Polynesia
In Polynesia numerous groups are found to have ambilineal descent systems. In the Northern Gilbert Islands ambilineal descent systems are evident in both Butaritari and Makin. In both groups ambilineal descent is understood through land ownership, occupation, and inheritance. Membership in an ambilineal descent group, often called a ramage, includes those who can trace their descent (through either the female or male line) to the founder of the group. As well as individuals who can trace their descent to the founder and have inherited land rights to a part of the founder’s estate. In this system an individual is not a member of every group they can genealogically trace kinship to. Rather, membership depends on land possession within the group. Upon marriage, couples have the choice in which group they want to join.
Ambilineal systems are also found in Samoa, Tonga and with Māori people in New Zealand. Similarly to Butaritari and Makin, land ownership and inheritance is the basis for membership and affiliation in a descent group, but in these three systems membership is most often based on the male line. In this system, both mother and father can be used for affiliation with a particular descent group, but emphasis is placed on the father. While it is most desirable for membership into the father’s group female links are also used especially when aligning with the female line brings increased power, wealth, or social standing