New light on the prehistoric Purrón Dam Complex: Small corporate group collaboration in the Tehuacán Valley, Puebla, México

The 2003 and 2004 surveys at the Purron Dam Complex (PDC) demonstrate the value of resurveying previously studied areas. Additional habitation sites, water management features, a cave with pictographs, and a major canal were discovered, increasing the number of recorded sites from eight to 57. From this survey, the collected ceramics and a synthesis of 12 chronometric dates suggest that water management was initiated in the complex by Early Formative times at ca. 1050-1100 B.C., and that the Purron Dam was completed by the Middle Formative Period (ca. 650-450 B.C.), when settlements were small and decentralized. This challenges previous interpretations that place the PDC florescence during the Early Classic Period (ca. 150 b.c-a.d.250), a period with larger aggregated communities displaying social ranking. The results of our survey have implications for understanding the links between political complexity and agricultural intensification, and support recent ethnographic and archaeological research discrediting the argument that increasing social complexity necessarily leads to the construction of large water management systems.