Lewis Henry Morgan (November 21, 1818 – December 17, 1881) was a pioneering American anthropologist and social theorist who worked as a railroad lawyer. He is best known for his work on kinship and social structure, his theories of social evolution, and his ethnography of the Iroquois. Interested in what holds societies together, he proposed the concept that the earliest human domestic institution was the matrilineal clan, not the patriarchal family.