Final answer:
The three major types of unilineal descent are patrilineal, matrilineal, and ambilineal. Patrilineal traces lineage through the father's line, matrilineal through the mother's line, and ambilineal allows a choice between the father's or mother's line.
Step-by-step explanation:
The three major types of unilineal descent are patrilineal descent, matrilineal descent, and ambilineal descent. Patrilineal descent traces an individual's lineage through the father's line only, and it is common in societies where males carry on the family surname, and inheritance or status is passed along the male line. In contrast, matrilineal descent follows the mother's line only, giving importance to the female lineage where inheritance and clan affiliation are determined through the mother's ancestry. Ambilineal descent, on the other hand, allows for either the father's or the mother's line to be chosen as the descent line, with this decision often made at marriage based on various social or economic considerations.