On the "macro" scale, social structure pertains to the system of socioeconomic stratification (most notably the class structure), social institutions, or other patterned relations between large social groups. On the "meso" scale, it concerns the structure of social networks between individuals or organizations. On the "micro" scale, "social structure" includes the ways in which 'norms' shape the behavior of individuals within the social system. These scales are not always kept separate. For example, John Levi Martin has theorized that certain macro-scale structures are the emergent properties of micro-scale cultural institutions (i.e., "structure" resembles that used by anthropologist Claude Levi-Strauss). Likewise, in ethnography, a recent study describes how indigenous social structure in the Republic of Panama changed macro social structures and impeded a planned Panama Canal expansion. Marxist sociology has also historically mixed different meanings of social structure, though doing so by simply treating the cultural aspects of social structure as phenomenal of its economic ones.