Political anthropology concerns the structure of political systems, looked at from the basis of the structure of societies. Political anthropology has its roots in the 19th century. At that time, thinkers such as Lewis H. Morgan and Sir Henry Maine tried to trace the evolution of human society from 'primitive' or 'savage' societies to more 'advanced' ones. These early approaches were ethnocentric, speculative, and often racist. Nevertheless, they laid the basis for political anthropology by undertaking a modern study inspired by modern science, and in particular Darwin. In a move that would be influential for future anthropology, they focused on kinship as the key to understanding political organization, and emphasized the role of the 'gens' or lineage as an object of study.Some notable political anthropologists include Pierre Clastres, E. E. Evans-Pritchard, Meyer Fortes, Georges Balandier, Carolyn Nordstrom, F. G. Bailey, Jeremy Boissevain, Marc Abélès, Ted C. Lewellen, Robert L. Carneiro, John Borneman and Joan Vincent.