born Nov. 21, 1818, near Aurora, N.Y., U.S.
died Dec. 17, 1881, Rochester, N.Y.
U.S. ethnologist and a principal founder of scientific anthropology.
Morgan developed a deep interest in the American Indians and in 1846 was eventually adopted by the Seneca . His Systems of Consanguinity and Affinity of the Human Family (1871) was a world survey of kinship systems that sought to establish connections between cultures and particularly to establish the Asiatic origin of the American Indians. This work led to a comprehensive theory of sociocultural evolution , set forth in Ancient Society (1877). He claimed that advances in social organization arose primarily from changes in food production and that society had progressed from a hunting-and-gathering stage ("savagery") to one of settled agriculture ("barbarism") to modern "civilization." This theory, with the related theory that society originated in a state of sexual promiscuity and advanced through various forms of family life before culminating in monogamy, is now obsolete. For many years, however, Morgan was the dean of American anthropology, and his pioneering ideas influenced the theories of Karl Marx and Friedrich Engels , among others.