Final answer:
Unilineal descent is a form of kinship tracing where an individual's lineage is followed through only one parent's line, either matrilineal or patrilineal. It is used in various societies and can determine familial relationships, inheritance, and societal roles.
Step-by-step explanation:
Unilineal descent is a system of tracing kinship through only one parent's lineage, either the mother's or the fathers, but not both. Within unilineal descent, we can distinguish between three main types: patrilineal descent, which follows the father's line only, matrilineal descent, which traces through the mother's side only, and ambilineal descent, giving the option to choose between the mother's or the father's line based on familial advantages at the time of marriage.
In patrilineal societies, as observed in rural China and India, the family surname is typically passed on only through the male members, which bestows upon them a sense of permanent family inclusion. In contrast, females in such societies are often perceived as only temporary family members. Even in countries like the United States, which primarily follows a bilateral kinship pattern—tracing descent through both parents—there remain elements of patrilineal descent such as children commonly inheriting their father's surname. Meanwhile, in matrilineal descent, kinship is determined solely through the line of female ancestors, which means that both males and females carry the lineage of their mothers.