Final answer:
Unilineal descent traces a person's kinship through a single line of ancestry, focusing either on the patrilineal or matrilineal line. Patrilineal follows the father's line, while matrilineal follows the mother's line. Ambilineal descent allows families to choose either line to trace their ancestry.
Step-by-step explanation:
Unilineal descent traces a person's descent only through a single line of ancestry, either male or female. There are three main types of unilineal descent: patrilineal descent, which traces kinship through the father's line only, matrilineal descent, which traces kinship through the mother's side only, and ambilineal descent, which allows a choice between tracing through the father's or mother's line.
In patrilineal (agnatic) descent, both males and females trace their descent through their male ancestors. Typically, in these societies, males carry on the family surname and are viewed as the permanent members of their family lineage.
Conversely, in matrilineal (uterine) descent, both males and females trace their lineage exclusively through their female ancestors.
Lastly, ambilineal descent provides flexibility, as families can choose to follow either the mother's or father's side for tracing their kinship.