Morgan became interested in the Native Americans during his days with the Grand Order of the Iroquois. While studying Seneca society, he was formally incorporated as an adopted member, in part to honor his work with them to preserve their reservation lands from being taken by European Americans. They named him Tayadaowuhkuh, meaning bridging the gap (between the Iroquois and the European Americans.)
Morgan met and became friends with Ely S. Parker, of the Seneca tribe and the Tonawanda Reservation. Classically educated and a diplomat on behalf of the Seneca, Parker had also studied law. With his help, Morgan studied the culture and the structure of Iroquois society. Morgan had noticed they used different terms than Europeans to designate individuals by their relationships within the extended family. He had the creative insight to recognize this was meaningful in terms of their social organization. He defined western terms as "descriptive" and Iroquois (and Native American) terms as "classificatory", terms that continue to be used as major divisions by anthropologists and ethnographers.
Based on his extensive research, Morgan wrote and published The League of the Ho-de-no-sau-nee or Iroquois (1851). He demonstrated the importance of Parker's contribution by dedicating it to him and "our joint researches."[2] This work, which presented the complexity of Iroquois society, was a pathbreaking work of ethnography and a model for future anthropologists.
Morgan presented the kinship system of the Iroquois with unprecedented nuance. After putting aside scholarship to devote himself to his own family and his work as a lawyer, his interest in kinship and human social organization was reignited in the late 1850s. This time, Morgan expanded his research far beyond the Iroquois. American and European scholars had widely varying ideas about the origin of Native Americans. Morgan had begun to believe they originated in Asia. He thought he could prove it by a study of kinship terms used by people in Asia as well as tribes in North America.
He determined to collect and sort the systems of relationship terms used by tribes spanning the greater part of the United States of America, and then collect data from peoples across the globe. With the help of local contacts and after intensive correspondence over the course of years, this research culminated in Morgan's seminal Systems of Consanguinity and Affinity (1871)[3], which was printed by the Smithsonian Press. It "created at a stroke what without exaggeration might be called the seminal concern of contemporary anthropology, the study of kinship..."[4] In this work, Morgan set forth his argument for the unity of humankind. At the same time, he presented a sophisticated schema of social evolution based upon the relationship terms, the categories of kinship, used by peoples around the world. Through his analysis of kinship terms, Morgan discerned that the structure of the family and social institutions develop and change according to a specific sequence.
In the years that followed, Morgan developed his theories. Combined with an exhaustive study of classic Greek and Roman sources, he crowned his work with his magnum opus Ancient Society (1877). Morgan elaborated upon his theory of social evolution. He introduced a critical link between social progress and technological progress. He emphasized the centrality of family and property relations. He traced the interplay between the evolution of technology, of family relations, of property relations, of the larger social structures and systems of governance, and intellectual development.
Looking across a vastly expanded span of human existence, Morgan presented three major stages: savagery, barbarism, and civilization. These stages were further divided and defined by technological inventions, such as use of fire, bow, pottery in the savage era; domestication of animals, agriculture, and metalworking in the barbarian era; and development of the alphabet and writing in the civilization era. (In part, this was an effort to create a structure for North American history that was comparable to the three ages of European pre-history, developed by scholars in Denmark during these years.)[5]
Morgan's final work, Houses and House-life of the American Aborigines (1881), was an elaboration on what he had originally planned as an additional part of Ancient Society. In it, Morgan presented evidence, mostly from North and South America, that the development of house architecture and house culture reflected the development of kinship and property relations.
Many specific aspects of Morgan's evolutionary position have been rejected by later anthropologists. His real achievements remain impressive. He founded the sub-discipline of kinship studies. Anthropologists remain interested in the connections which Morgan outlined between material culture and social structure. His impact has been felt far beyond the Ivory Tower.
Although Karl Marx never finished his own book based on Morgan's work, Frederick Engels continued his analysis. Morgan, a capitalist, railroad lawyer and Republican state legislator, strongly influenced Engels' sociological theory of dialectical materialism (expressed in his work The Origin of the Family, Private Property, and the State, 1884). Scholars of the Communist bloc considered Morgan became the preeminent anthropologist.[6]
Morgan believed that American greatness rested upon the diffusion of property and political power. He was strongly against class systems and the structure of feudalism. He believed that wage-earning would be and should be only a stage of life in the United States: after the American Civil War, he grew increasingly worried about the concentration of wealth and power among the elite. In his social theory, he demonstrated that progress was driven by greed. He was nostalgic for the virtues that he saw among the classical Stoics, among Native Americans and other "primitive" peoples. He was concerned that what he called "the mere property career" was spinning out of control. His faith in the human capacity to learn, to cope with the surroundings, to adapt, to, in short, progress, enabled him to overcome his ambivalence about the mixed results. Looking to the future, he foresaw a revival, in new form, of "the liberty, equality and fraternity" of primitive peoples.