2.3. Chemical provenience and exchange

In the early twentieth century archaeologists investigated prehistoric exchange, primarily by using stylistic criteria, in order to demonstrate contact between two culture areas from a diffusionist perspective. Modern studies of exchange through scientific sourcing began with the work of Anna O. Shepard (1956) who found that petrographic analysis of ceramic tempers could be used to differentiate ceramic types. Since Shepard's early work, methods for chemically characterizing artifacts has grown rapidly (Glascock 2002). By the late 1960s, with geochemical evidence for long-distance interaction accumulating worldwide, archaeologists began developing systematic approaches to evaluating exchange.

The fundamental issue for many archaeological studies of exchange is that exchange processes have social evolutionary consequences (see Section 2.2.3 ). In current debates over the role of exchange, theoretical approaches range from those premised on looking at efficiency in production and exchange, and those approaches that focus on the role of social dynamics and agency models for long-distance relationships.