clan, social group based on actual or alleged unilineal descent from a common ancestor. Such groups have been known in all parts of the world and include some that claim the parentage or special protection of an animal, plant, or other object (see totem). They also include such familiar groups as the Highland clans of Scotland (the English word clan comes from Gaelic). Most clans stress mutual obligations and duties. Clan descent is traced in one line only, male or female. The word clan has by some been restricted to those descended through the mother (matrilineal) in contrast to the gens, descended through the father (patrilineal). The word sib has been much used to cover both types. A clan includes several family groups. Most clans are exogamous and regard marriages among their members as incest. A clan is distinguished from a lineage in that a clan merely claims common ancestry; a lineage can be traced to a common progenitor. A clan may have several lineages. Several clans may be combined into a larger social group called a phratry. If a tribe includes two clans or phratries, each clan or phratry is called a moiety.

Kinship group based on actual or purported descent from a common ancestor, as traced through the male (patriclan) or the female (matriclan) line. Clans are normally exogamous, marriage within the clan being regarded as incest. Clans may segment into subclans or lineages, and genealogical records and myths may be altered to incorporate new members who lack kinship ties with the clan. Clan membership may be useful in ensuring mutual support and defense as well as in the mediation of disputes over property rights and the mode of residence after marriage. Some clans express their unity by means of a common emblem. Seealso exogamy and endogamy.

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