Bitumen control and exchange among the Olmec

To understand if and how bitumen resources were controlled and the nature of trade relationships among the Olmec, this study compared the chemical signatures of 34 modern bitumen seep samples collected in the Olmec region of Mesoamerica with the chemical signatures of 48 archaeological bitumen samples excavated from Early and Middle Formative period (1450-1000 B.C.) sites in Mesoamerica. Hierarchical cluster analyses (HCA) were performed on gas chromatography-mass spectrometry (GC-MS) biomarker ratio data for the seeps and artifacts to correlate the archaeological bitumen specimens with their most likely seep sources. The seeps were clustered into groups and mapped; the archaeological bitumen was then added to the HCA to cluster the artifacts with their most probable seep source groups. This research used Renfrew's (1975) model of exchange; the distance the archaeological materials traveled was measured and the contexts in which they were found were analyzed to make inferences about the nature of Olmec commodity exchange. Most of the archaeological material came from sites in the San Lorenzo vicinity. Ten of the archaeological samples were not correlated with any seeps, and five seeps were not correlated with any artifacts. Seventeen artifacts, from the San Lorenzo area and found in both elite and non-elite contexts, were sourced to one particular seep in the San Lorenzo vicinity, suggesting that the seep may have been of higher quality than the material from other nearby seeps and that access was not controlled by the Olmec elite. Three artifacts found at the distant sites of Isla Alor, San Andres and Canton Corralito were sourced to the San Lorenzo vicinity and were probably obtained via exchange. The results of this study suggest that bitumen seeps varied in quality, that non-elites had open access to bitumen sources, and that the material was exchanged over long distances. No evidence of elite control was found. This research examines the economic organization of commodity exchange among one of the earliest complex societies in Mesoamerica.