Final answer:
Melvyn Goldstein researched the rare form of fraternal polyandry marriage in Tibet, highlighting its implications on Tibetan family and social structures.
Step-by-step explanation:
Melvyn Goldstein conducted his research on a rare form of marriage known as fraternal polyandry in the region of Tibet. This unique form of marriage, where multiple brothers share a single wife, was the focus of Goldstein's ethnographic work. Goldstein's research not only documents this cultural practice but also explores its implications for Tibetan family life and social organization. His seminal work, titled "When Brothers Share a Wife," sheds light on the complexities of kinship, inheritance, and familial responsibilities within this non-western form of marriage.