Obsidian source distribution and mercantile hierarchies in Postclassic Aztatlán, West Mexico

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] In Precolumbian Mesoamerica, trade was central to social organization, the spread of ideas, and the widespread distribution of goods across the landscape. For the Aztatlán tradition of Postclassic (AD 900- 1350) West Mexico in particular, far-reaching trade networks were a defining characteristic. One important trade item spread throughout the region was obsidian. While West Mexico features a wide array of excellent quality obsidian sources, they were differentially used in particular ways. In this study, I have macroscopically and geochemically analyzed over 14,000 total obsidian artifacts from seven different Aztatlan sites: San Felipe Aztatán, Coamiles, Chacalilla, Amapa, Peñitas, Huistla, and Santiaguito. Through these analyses, I have identified differences in how various obsidian sources were utilized nonrandomly not only within sites, but also among them. Results indicate that while the source closest to the coastal plain was utilized for generalized reduction and expedient tool use, more distant and presumably more costly sources were likely imported as prepared cores and finished prismatic blades. These obsidian analyses are supplemented with a geospatial study in which I have proposed the most efficient trade routes from each site to the utilized obsidian sources using a GIS Least Cost Path. With this, I have also identified likely direct trade between the regional centers on the coastal plain and secondary sites in Western Jalisco As a result, I have argued that obsidian sources were utilized in a manner dictated by the ideological value of particular sources based largely upon exclusivity and cost. To explore this hypothesis, I have utilized tenets of Neo-Marxist archaeological theory and Costly Signaling theory. With these theoretical perspectives, I argue that the greater cost, in and of itself, would have incentivized individuals with more wealth and prestige to preferentially use more distant obsidians. This utilization may have served to bolster their elevated status within local communities through the demonstration of greater access to resources, allies, esoteric knowledge of foreign lands, and trade partners. In this way, obsidian provides a window into better understanding the sociopolitical organization of the Aztatlán tradition.