How did Lewis Henry Morgan use contemporary societies to support his evolutionary stages?

Lewis Henry Morgan, a foundational figure in scientific anthropology, utilized contemporary societies to support his theory of cultural evolution by treating them as living representations of humanity's past stages.12

In his masterwork, Ancient Society (1877), Morgan posited that all human societies progressed through uniform stages—savagery, barbarism, and civilization—driven primarily by technological advancements and changes in food production and property ownership. He argued that because humanity shared a common origin, the history of contemporary indigenous tribes, such as the Iroquois, mirrored the experiences of his own remote ancestors.123

By comparing kinship terminology and social structures across diverse cultures, Morgan mapped these groups onto his evolutionary schema. For instance, he used "classificatory" kinship systems as evidence of earlier, less regulated forms of marriage, such as "group marriage," which he believed preceded the monogamy found in 19th-century European and Euro-American society. While his specific evolutionary stages are now considered obsolete, his emphasis on cross-cultural comparison and the material basis of social organization left an enduring mark on the field.231