A01_05

A Regional-Scale Bayesian Reevaluation of Radiocarbon Data from Early Formative Mesoamerica

Mejía Ramón A¹

¹Okinawa Institute Of Science And Technology, Onna-son, Japan

Early Formative Mesoamerica was witness to some of the most important transformations during the transition from hunter-gatherers to agricultural societies. Recently studies employing high-resolution AMS dating and Bayesian modeling have challenged long-held notions about the maize's synchronous appearance alongside sedentism and ceramics. Much less recent attention has been given to the settlement and ceramic chronologies themselves. This is unfortunate, since archaeologists largely rely on typologies dated decades ago before the widespread use of high-resolution AMS dating and Bayesian modeling. In this paper, I discuss a Bayesian re-analysis of 713+ published dates from 120+ sites (as of submission) spanning Panama through West Mexico, finding significant issues with the currently accepted narrative for the adoption of ceramics and transition to agriculture. I create cross-referenced stratigraphic models for every dated Early Formative site with published excavation information, nesting those within trapezium models for cultural phases unconstrained by a sequential assumption---in other words phases are allowed to overlap and are allowed to have a gap between them. I find that archaeologists have consistently discarded the earliest identified dates not for reasons of 'chronometric hygiene' but because they antecede the expected arrival of ceramics by hundreds of years despite a clear regional trend from at least the third millennium calBC. Furthermore, there is little evidence to support the hypothesis that Barra ceramics were necessarily the first ceramics in Mesoamerica or that they existed by themselves within the Soconusco. I suggest a moiety-like form of social organization expanding from Lower Central America to explain the observed record.