lignage

Latin linea (a line, a thread) came from linum (flax, linen thread) — the straight line was originally a thread of flax stretched taut. Linea gave Old French ligne and the derivative lignage: descent, ancestry, the sequence of people connected by birth across generations. The thread metaphor was apt: lineage stretched backward and forward, connecting the living to ancestors and to descendants not yet born.

Anthropology distinguishes lineages from clans, families, and other descent groups by a specific criterion: a lineage traces its members through a single line of descent, either patrilineal (through fathers) or matrilineal (through mothers), back to a specific known ancestor. A clan is similar but may trace descent to a mythological or totemic ancestor rather than a historically documented one. The Somali lineage system, for example, enables any person to recite their patrilineal ancestry for forty or more generations.

Lineage systems determined inheritance, political authority, marriage rights, and social identity across many cultures. In the feudal systems of medieval Europe, establishing lineage was essential for inheriting titles and lands. In traditional African political systems, lineage determined who could become chief. Among the Confucian-influenced societies of East Asia, patrilineal lineage organized family organization, ancestor veneration, and social hierarchy.

Modern genetic genealogy has transformed lineage research. Y-chromosome analysis traces unbroken patrilineal descent; mitochondrial DNA traces unbroken matrilineal descent. The 'Adam' and 'Eve' of human genetics — the patrilineal and matrilineal ancestors of all living humans — were not contemporaries; the Y-chromosome ancestor lived approximately 200,000-340,000 years ago, the mitochondrial ancestor approximately 150,000-200,000 years ago. The thread runs very long.